Beef for Tomorrow: Conference Proceedings (1960)

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THIRD SESSION How to Produce Beef Economically M. L. Baker, presiding Type and Quality in the Live Beef Animal and in the Carcass O. D. Butler Texas A. &: M. College DISCUSSION of this topic is justified by the belief that marketing of slaugh- ter cattle on foot will continue to be the trading system of choice for most packers and producers. The accuracy of evalua- tion of characteristics contributing to variations in value obviously improves as the beef progresses toward the consumer's plate. Dressing percentage is not impor- tant when the carcass weight is known. Carcass weight is not important when the weight of the component trimmed whole- sale cuts is known, and value at retail is finally established rather definitely when retail cuts are processed, weighed, pack- aged, and priced. "Quality" is a very ambiguous word. To showmen it may refer to style and sym- metry, haircoat, length, thickness, luster, or color markings, and even excellence of fitting including dehorning, hoof trim- ming, clipping, and grooming. Meats men estimate "quality" by the appraisal of fac- tors thought to be related to the eating desirability of the beef, but consumers just decide on the basis of the tenderness, juici- ness, and flavor of the cooked meat. Ac- curacy of appraisal decreases at each proc- essing point along the chain from the din- ner plate to the live animal. Efficient movement of about 14 billion pounds of perishable beef to U. S. con- sumers annually has fostered a sense of urgency and an attitude of "the less han- dling and processing the better" all along the line from the slaughterer to the re- tailer." Low margins make high volume necessary for processing profit. If con- sumers were really hungry and beef had a monopoly on the protein food market, buyers would not be very discriminatory in their beef purchases. The abundance of protein foods and the general pros- perity and strong buying power, however, make most Americans very critical shop- pers. In fact, beef purchasing habits might be as good as automobile purchases in stratifying people according to income and position. For the foreseeable future, we must conclude that people will be willing to pay more for preferred cuts of beef than for less preferred cuts, and that preferred cuts approaching ideal tender- ness, juiciness, and flavor will bring top prices if properly identified and offered for sale. Therefore, cattle that yield a higher proportion of preferred cuts combined with excellent "quality" beef from the viewpoint of discriminating, informed, and prosperous consumers will certainly be more valuable than average cattle. We just need to identify such cattle and allow free play of economic forces. That 75

76 BEEF FOR TOMORROW is a large order. Researchers have been attempting to develop better identification methods for many years. Progress has been slow. Lush (9) made 17 measurements on 185 steers during dry lot feeding to record the changes in conformation during intensive fattening. The data were treated statisti- cally and many ratios were calculated, but no reference to carcass characteristics was made. Lush (10) added 56 steers to the original 185 and related measurements to rate of gain, dressing per cent, and "value" of dressed carcass. The "value" was the appraised price per pound for the dressed carcass set by packer beef men. Though Lush's data were detailed and were ana- lyzed statistically in a classical manner, comparison to an appraised carcass char- acteristic reduced the usefulness of the results. Black et al (1) refined the techniques of Lush, and applied 9 live measurements to 50 record of performance steers of beef, dual-purpose, and dairy breeding. The steers were produced under standardized conditions and slaughtered at a uniform weight of 900 pounds. Live measurements were correlated with gain, dressing per- centage, percentage of fat in the carcass, percentage of total edible meat, and slaughter grade. Their results confirmed observations of Lush (10) that steers shorter in height, shorter legged, and shallower bodied were higher in efficiency of feed utilization, had more fat, more edible meat, and less bone in the carcass than the taller, longer legged, deeper bodied animals. "Edible meat" appar- ently included all the fat as well as the lean meat, which reduces the present ap- plication of their results. Black et al (1) found visual observation to be superior to the measurements used, because "measure- ments cannot show exactly the symmetry and proportions that should exist in a good beef-type animal." No other data were given on meat yields. Hankins and Howe (7) standardized cutting procedures for beef carcasses, and developed a valuable sampling method for estimating the lean, fat, and bone in car- casses without complete physical separa- tion. Naumann (12) presented the method of Hankins and Howe with slight modifi- cations, and the procedure was adopted by the Reciprocal Meat Conference. Cook et al (4) reported on the relation- ship of 5 live measurements on 157 Milk- ing Shorthorn steers produced under standard conditions at Beltsville, Mary- land, with slaughter grade, carcass grade, and dressing percentage. Their data gave 12 out of 15 significant correlation coeffi- cients but the relationships were not high enough to be of predictive value, as the highest was .51. The correlation between slaughter grade and carcass grade, how- ever, was .69. White and Green (16) related measure- ments of live steers to weights of whole- sale cuts. Fifty beef-type steers were used weighing from 800-1,440 pounds and grad- ing medium to choice. Thirty-six linear measurements were made with detailed statistical treatment of the data, including multiple correlation coefficients. Their high correlations included live weight in the formula, which is obviously related to the weight of wholesale cuts, and contrib- uted greatly to the multiple correlation coefficients because of the wide spread in weight of the cattle. Green (6) related the data taken on the 50 steers reported by White and Green (1952) with combined weights of preferred cuts including round, trimmed loin, and rib (I), and the latter combined with the "cross cut" (II). He emphasized the im- portance of shoulder width and width through the thighs as indicators of carcass muscling. Depth of chest was not a good indicator of dressing percentage or pre- ferred cut weights. Compactness was not associated with higher yields of preferred cuts. Width of shoulders and hooks and depth of twist were more highly correlated with the yield of preferred cuts than other linear measurements. Yao et al (19) related 8 meat production characters with 19 body measurements on

PRODUCING BEEF ECONOMICALLY 77 101 beef Shorthorn steers and 62 Milking Shorthorn steers raised at Beltsville. All of the width and circumference measure- ments were positively correlated with slaughter grade, carcass grade, and dress- ing percentage. All of the height and length measurements were negatively cor- related with slaughter grade. No carcass cut-out values were reported. Woodward et al (17) reported relation- ships between preslaughter evaluations of beef cattle. Their data were taken on 635 steers produced at Miles City, Mon- tana between 1941 and 1951. The corre- lation between slaughter grade and car- cass grade was .54, with much lower co- efficients for area of eye muscle (.16), thickness (.22), dressing percentage (.19), length of body (.15), and length of leg (.OS) compared to slaughter grade. Thickness of fat was related higher (r = .43) with carcass grade than was area of eye muscle (r = .08). They stated that "since the ultimate value of the carcass is enhanced more by a large eye muscle than by excess external fat, it is possible that thickness of external fat received too strong a consideration in the grading." The relationships between body meas- urements and area of eye muscle, thickness of fat, and dressing percentage were less than .50, but "length of leg" in the car- cass was rather closely related to length of body alive (r = .77). No cut-out data were taken. Kidwell (8) reported on the relation- ship of beef conformation and carcass quality in beef calves. Actually the 64 steers used were exhibited at the 1954 Nevada Junior Livestock Show, and ranged in age from 10 to 16 months. The correlation of slaughter grade with carcass grade was .60. Body measurements were correlated with slaughter grade, carcass grade, and dressing percentage, but no cut-out data were reported. Butler (2) reported the results of the Texas Agricultural Experiment Station beef carcass cut-out tests for the previous six years. The most important conclusion reached was that animals of the same fat- ness may vary considerably in conforma- tion without affecting the percentage of wholesale cuts materially. The main fac- tor influencing the percentage yield of wholesale cuts is the fatness of the carcass. Bones and muscles tend to develop pro- portionately, but fat is deposited unevenly over the body. Tallis et al (15) of the Ohio Agricul- tural Experiment Station related body measurements to beef type and certain carcass measurements. Their basic cri- terion of carcass "meatiness" was the "edi- ble portion," as developed by Professor L. E. Kunkle and his group. On a side of beef, this consists of boneless cuts trimmed to 3/8 inch fat cover or less along with the boneless lean trim. This is an exacting test. Ten live measurements were made, cir- cumference of heart girth, navel, and fore- arm, width of chest and hooks, depth of chest and twist, height of withers and hooks, and length of body. Repeatability of measurements as taken by two investi- gators on the same steers was good except for circumference of forearm and depth of twist. They found that animals with a high ratio of weight to height (low-set) and with a high ratio of weight to length (compact) tended to have larger ribeyes, but a smaller edible portion percentage. They explained that the ratios were ap- parently positively correlated with carcass fat, and thus negatively related to edible portion, since the latter is highly influ- enced by the amount of fat trim. Several workers are presently engaged in developing objective measures of mus- cling and lean-fat-bone variations in live animals by application of ultrasonics and specific gravity measurement. Stouffer seems to be developing ultrasonic meas- urements to usable accuracy in estimating area of ribeye of live cattle and swine. Pearson (14) and the group at Michigan State University are making progress in the use of an air chamber for determina- tion of specific gravity by air displace- ment. Their appraisal of the application

78 BEEF FOR TOMORROW of this technique is envisioned as follows: "The specific gravity obtained by air displacement is a means by which leanness of animals can be measured directly. Cur- rent methods of determining body compo- sition arrive at leanness via a direct meas- ure of fat. "If this method can be adapted to measure leanness of whole droves of ani- mals, it can be used to more accurately de- termine the worth of market animals. Also, when using individuals, this method can be applicable as an aid in the selec- tion of animals for breeding programs." Fat slaughter cattle that look very simi- lar alive are likely to show marked varia- tion in carcass muscling. This is of major concern to the beef industry. Fulk (5) re- ported the loin eye and fat cover measure- ments for 384 cattle shown at the Inter- national. His data are shown in Table 1. The variability shown by such selected cattle is great, and should be of concern to beef producers. Some of our major packers are at- tempting to improve the ability of their cattle buyers to select steers and heifers with superior muscling within the various grades. J. N. Jones of Swift &: Company, and Fred Haigler of Armour and Com- pany reported on their programs at the American Hereford Association research meeting March 19 and 20, 1959. Mr. C. A. Rheinberger of the Beef Department, TABLE 1 Loin Eye and Fat Cover Measurements (Average of 384 cattle that were shown in the International Carcass and Carlot Contests) Live Weight Loin Eye Sq. In. Fat Cover Inches Per Thousand Loin Fat Junior Yearlings 1,150 (Avg. 21 months) (75% Prime—25% |f Choice) Summer Yearlings 1,000 (Avg. 17 months) (60% Prime—35% Choice—5% Good) Senior Calves 875 (Avg. 13 months) (35% Prime—45% Choice—20% Good) 384 Steers 1,000 Smallest Loin Eye Largest Loin Eye Smallest Loin Eye per 1,000 pounds Largest Loin Eye per 1,000 pounds Most Fat Cover on a Prime Steer Least Fat Cover on a Prime Steer 12.2 11.0 10.1 VARIATIONS 1.4 1.0 0.7 10.5 11.0 11.5 11.0 7.65 sq. in. 1,035 pound steer 16.2 sq. in. 1 , 250 pound steer 7.8 sq. in. 1 , 145 pound steer 14.9 sq. in. 840 pound steer 2.33 in. on a 1,192 pound steer .47 in. on a 900 pound steer 1.2 1.0 0.8 1.0

PRODUCING BEEF ECONOMICALLY 79 Cattle Buying Division, Swift & Company, Chicago, recently stated that they had not recorded statistical data, and were unable to report facts at this time. "The prob- lem of excessive waste material on cattle is still with us, however, and we are con- stantly reminding buyers in our day to day operations that it is necessary to dis- count fat, rindy, wasty cattle." Though we all admit to being rank amateurs, staff members at Texas A. and M. are attempting to learn to estimate carcass traits of live animals more accu- rately. Table 2 indicates the accuracy of estimates at present as shown by the data on a recent group of experimental steers. Substantial progress has been made by swine breeders in improving the yield of lean cuts on slaughter hogs. The lean cuts of pork are anatomically quite com- parable to the preferred cuts of beef. The answer to higher percentage yields of lean cuts in hogs is the combination of superior muscling and reduced external fat. The same prescription will work for beef cattle, though extremes of weight, age, and other factors complicate the problem. Evidences of superior muscling in hogs may apply to cattle, such as turn of top, shoulder muscling, wide set front and hind legs, and well developed "hams." Cattle with extremely good or extremely poor muscling can be identified, but those clustering more closely around the aver- age are difficult to rank. Progeny testing with direct selection for the most important production and car- cass traits seems to be one pathway to progress. Artificial insemination can spread the influence of a few top sires tremendously. Some of the "quality" factors tradition- ally checked on slaughter cattle are refine- ments of head, hide and bone, and fine- ness and luster of the haircoat. Small heads and thin hides increase dressing per- centage. Refined bones may actually be related to inferior muscling (11, 13, 18). It is inconsistent to select for heavy boned breeding cattle and light boned slaughter cattle. Cartwright et al (3) measured the hair density and diameter on slaughter steers and compared to the tenderness of the TABLE 2 Correlation of Live Estimates with Actual Measurements Carcass Sum Loin + Rib + Round & Ribeye Area/cwt. Chilled Dressing % Grade Ribeye Area Rump Carcass No. Steers 41 41 41 41 48 Estimator A B C D E Measurement Range .64 .74 .68 .62 .43 .51 .40 .49 .31 .21 .51 .27 .43 .37 .27 .04 .17 .13 .21 .83 54-63.8% Std.-toGood 7.3-10.5 46.1-51.6% sq. in. .35 .45 .47 .34 1.4-2.3 sq. in. Required for significance: 0.1 = .39 0.5=.30

80 BEEF FOR TOMORROW beef. No significant relationship was shown. So far no short cuts to feedlot tests have been found to establish gaining ability of cattle. Tables 3 and 4 present data on two small demonstration groups of fat slaugh- ter steers weighing about 1,000 pounds. These cattle were selected from groups of about 20 steers of each breed and used to demonstrate the variability in value of such cattle. It is interesting to note that the steer in each group with the least fat had the most tender meat. This could easily have been coincidental, but does point out that tenderness is not highly correlated with fatness. It is also interesting that the price spread between choice and prime was not enough to offset the higher cut-out per- centage of the low choice steer No. 1 in the Angus group, so the carcass value per cwt. actually figured higher for the low choice than for the prime. We must conclude that slaughter steers of approximately the same live weight and grade vary significantly in value on the basis of their retail yield of various cuts. The increased value is related closely to superior muscling and reduced outside fat covering. No objective measures have been developed to characterize and rank live steers accurately, but the extremes can be identified visually. Ultrasonic meas- urement of muscling and specific gravity estimation by air displacement show some promise, but their application to selection of breeding animals seems more likel) than to slaughter animals, because trading on a carcass basis probably would be sim- pler. Production of slaughter cattle with su- perior cut-out and beef desirability is a logical goal for beef cattle producers, and progress will tend to stabilize the majestic position of beef in the American diet. TABLE 3 Demonstration Hereford Steers About 1,000 Pounds Carcass Ribeye Area Ribeye/ Fat Covering % Loin + Total Shear Animal Grade Area cwt. Chid. over Ribeye Rib + Rnd. Value Force Ibs. No. USDA Sq. In. Care. Sq. In. Inches Retail cwt. Care. (24 hr. chill) 1 Av. Ch. 14.83 2.15 .77 37.34 $46.50 9.38 2 Av. Ch. 13.26 2.01 .97 36.51 46.34 10.69 3 H. Ch. 11.41 1.68 1.55 30.11 41.30 12.63 TABLE 4 Demonstration Angus Steers About 1,000 Pounds Animal No. Carcass Grade USDA Ribeye Area Sq. In. Area Ribeye/ cwt. Chid. Care. Sq. In. Fat Covering over Ribeye Inches %Loin + Rib + Rnd. Retail Total Value cwt. Care. Shear Force Ibs. (24 hr. chill) 1 L. Ch. 11.78 1.81 .80 36.36 $45.29 6.37 2 L. Pr. 10.45 1.48 1.53 31.16 44.53 8.56 3 Pr. 9.80 1.46 1.30 32.50 45.08 7.69 4 L. Ch. 9.69 1.55 1.10 33.07 42.55 8.13

PRODUCING BEEF ECONOMICALLY 81 References 1. Black, W. H., B. Knapp, Jr. and A. C. Cook. 1938. Correlation of body measurements of slaughter steers with rate and efficiency of gain and with certain carcass characteris- tics. J. Ag. Res. 56:465. 2. Butler, O. D. 1957. The relation of confor- mation to carcass traits. J. An. Sci. 16(1): 227. 3. Cartwright, T. C. 1959. Phenotypic Correla- tions Between Diameter and Density of Hair and Tenderness of Beef. J. An Sci. (in Press). 4. Cook, A. C., M. L. Kohli and W. M. Dawson. 1951. Relationships of five body measure- ments to slaughter grade, carcass grade, and dressing percentage in Milking Shorthorn steers. J. An. Sci. 10:386. 5. Fulk, Kenneth R. 1959. A carcass approach to beef cattle improvement. Proc. of Ninth Annual Beef Cattle Short Course, Texas A. and M. College, 9:48. 6. Green, W. W. 1954. Relationships of mea- urements of live animals to weights of grouped significant wholesale cuts and dressing percent of beef steers. J. An. Sci. 13:61. 7. Hankins, O. G., and P. E. Howe. 1946. Esti- mation of the composition of beef carcasses and cuts. U.S.D.A. Tech. Bui. 926. 8. Ridwell, J. F. 1955. A study of the relation between body conformation and carcass quality in fat calves. J. An. Sci. 14:233. 9. Lush, J. L. 1928. Changes in body measure- ments of steers during intensive fattening. Texas Agr. Exp. Sta. Bui. 385. 10. Lush, J. L. 1932. The relation of body shape to feeder steers to rate of gain to dressing percent and to value of dressed carcass. Texas Agr. Exp. Sta. Bui. 471. 11. McMeekan, C. P. 1956. Beef carcass judging by measurement. The Pastorial Review and Graziers Record 66:1273. 12. Naumann, H. D. 1951. A recommended pro- cedure for measuring and grading beef for carcass evaluation. Proc. Fourth Ann. R.M.C. National Live Stock and Meat Board 89. IS. Orts, Frank A. 1959. Bone muscle relation- ship. Proc. Twelfth R.M.C. National Live Stock and Meat Board (Unpublished). 14. Pearson, A. M. and Richard Gnaedinger. 1959. Specific gravity by air displacement. Proc. Twelfth R.M.C. National Live Stock and Meat Board (Unpublished). 15. Tallis, G. M., Earle W. Klosterman and V. R. Cahill. 1959. Body measurements in rela- tion to beef type and to certain carcass characteristics. J. An. Aci. 18(1): 108. 16. White, F. E. and W. W. Green. 1952. Rela- tionships of measurements of live animals to weights of wholesale cuts of beef. J. An. Sci. 11:370. 17. Woodward, R. H., J. R. Quesenberry, R. T. Clark, C. E. Shelby and O. G. Hankins. 1954. Relationship between pre-slaughter and post-slaughter evaluation of beef cat- tle. U.S.D.A. Cir. 945. 18. Wythe, L. D., F. A. Orts and G. T. King. 1959. Bone-muscle relationships in beef. J. An. Sci. (accepted for publication). 19. Yao, T. S., W. M. Dawson and A. C. Cook. 1953. Relationships between meat produc- tion characteristics and body measurements in beef and Milking Shorthorn steers. J. An. Sci. 12:775.

Genetic Aspects of Production Efficiency in Beef Cattle E. J. Warwick United States Department of Agriculture MAXIMUM improvement of production efficiency of beef cattle through breeding depends upon (1) a knowledge of the types, relative importance, and in- ter-relationships of hereditary variation present in available stocks, and (2) utili- zation of this knowledge to make matings or design breeding systems to most fully exploit hereditary variations. Although much remains to be learned, research dur- ing the past 30 years and particularly dur- ing the past 15 years, has set the stage for substantial genetic improvement in most characters influencing economy of produc- tion and consumer desirability of product. Table 1 summarizes material accumu- lated to date on heritability of several im- portant traits influencing efficiency of pro- duction and carcass quality. Estimates as given here are heritability in the nar- row sense and, for the most part, include only additive gene effects. Characters with medium to high heritability are those for which individual selection within a population should be at least moderately effective and for which the production of high performing crossbreds or linecrosses will depend, to a large extent at least, upon crossing of productive parent stocks. Improvement in characters of low herit- ability, if capable of genetic improvement, will depend upon judicious crossing and perhaps selection for crossing ability rather than on selection for performance as such. Speaking generally, it appears that all the traits studied to date relating to growth, efficiency of gain, conformation scores, and carcass characteristics have heritabilities high enough that selection should be effective. Only a few estimates of heritability of factors related to repro- ductive rate are available but they are uniformly low and, taken together with the more voluminous literature on genetic aspects of reproductive efficiency in dairy cattle, lead to the belief that selection is not likely to be effective. Presumably automatic selection (i.e., infertile breed- ing stock leaves a lower than average num- TABLE 1 Heritability Estimates for Beef Cattle Characters1 Calving interval 3 8 Birth weight 15 41 Weaning weight 29 29 Cow maternal ability 2 40 Post weaning feed-lot gain 19* 47 Efficiency of feed-lot gain 8* 40 Final feedlot weight 9 69 Post weaning pasture gain 9» 34 Cancer eye susceptibility 2 32 Live animal scores Weaning 18 27 18 mon. off grass 7 27 Slaughter 7 44 Carcass traits Dressing percent 2 71 Carcass grade 6 32 Rib eye area 3 69 Tenderness 5 58 Character No. of Ave of Estimates Estimates 1 Most pertinent references are given in Warwick (45). Additional references include Blackwell et al. (2), Shelby et al. (38), Kincaid and Carter (27), Carter and Kincaid (7, 8), Brown (13), Cartwright el al. (9, 10), Gaines et al. (20), Wagnon and Rollins (44) Dinkel (17), Alsmeyer et al. (1), and Keifer et al. (26). 1A few unreasonably high or low estimates omitted. 82

PRODUCING BEEF ECONOMICALLY 83 her of offspring) has nearly exhausted whatever genetic variability may have once existed in most breeds reared under a variety of environmental circumstances. Breed differences for some components of fertility do apparently exist, at least in some environments, and their existence leads to the hypothesis that breeds may have plateaued at different levels for dif- ferent reproductive factors. Thus, repro- ductive performance may have potential for improvement through crossing. The above statements on probable inef- fectiveness of selection for fertility within breeds must be taken with some reserva- tions since Knox (29) found a difference in calf crop of 12.2 per cent in favor of large type as compared to compact Here- ford cows. He hypothesized that the large cows were better adapted to the rigorous New Mexico range conditions where the experiment was conducted and thus able to maintain higher reproductive rates. Stonaker (40) found that conventional cows raised 8.4 per cent higher calf crops than Comprest cows under Colorado range conditions. Studies of heritability of var- ious components of reproductive ability have not been made under severe environ- mental conditions. Such studies could conceivably give different results than those reported thus far. Probable Effectiveness of Selection The fact that hereditary differences exist in important production characters is of academic interest until considered in rela- tion to the amount of variability present in a population and the intensity of se- lection which can be obtained. The formulas developed by Dickerson and Hazel (14) have been used and ex- tended where necessary to estimate prog- ress attainable for a few traits and a few selection systems (Table 2). The estimates apply to large populations where only one character is being selected for at a time. The selection plans are: (80 per cent calf crops and 50 per cent sex ratio assumed) /. For Cows: (cows calve first at 3 years and 5 per cent annual attrition assumed) 60 per cent of all heifer calves retained for breeding with 50 per cent of these culled on calf performance after 2 calf crops. Remainder used to 10 years of age. TABLE 2 Estimates of Annual Genetic Improvement Possible in Large Beef Herds Under a Few Possible Breeding Systems when Selection Is For One Trait Only Weaning Weight1 Postweaning2 Feedlot Gain Efficiency of3 Postweaning Gain Area of4 Rib Eye Tenderness6 Bull Plan A (Natural Service) Bull Plan C (Natural Service) Bull Plan D (Art. Insem.) Bull Plan E (Art. Insem.) Bull Plan F (Art. Insem.) Bull Plan G (Art. Insem.) 4.31b. 4.81b. 5.91b. 6.51b. 6.31b. 8.81b. .0431b. day .047 Ib. day .0601b. day .0591b. day .065 Ib. day .069 Ib. day -8.401b. -9.241b. -11.821b. -11.82 Ib. -12.66 Ib. -13.261b. .029sq. in -.0881b. - . 120 Ib. -.1121b. -.1951b. .OK) si;, in .034 sq. in . 065 sq. in .074 sq. in -.2221b. 1 Assumed heritability of 30 per cent; standard deviation of 40 Ib. 1 Assumed heritability of 45 per cent; standard deviation of .3 Ib. for males and .25 Ib. for females; gain ex- pressed in terms of average daily gain. * Assumed heritability of 40 per cent; standard deviation of 60 Ib. Efficiency expressed as pounds of TDN consumed per 100 Ib. gain. Improvement in feed efficiency is denoted by reduction in feed required. 4 Assumed heritability of 50 per cent; standard deviation of 1.0 square inch. Selection based entirely on informa- tion from sibs and progeny. 'Assumed heritability of 50 per cent; standard deviation of 3.0 Ib.; expressed in pounds of force required to shear a one inch core in the Warner-Bratzler shear. Selection based entirely on information from sibs and progeny. Improvement in tenderness is denoted by reduction in pounds of force required.

84 BEEF FOR TOMORROW 2. For Bulls: (30 per cent annual attri- tion assumed for bulls over 3 years of age) Plan A. 5 per cent of all bulls saved, used in natural service at ages of 2 and 3, then discarded. Plan C. 5.6 per cent of all bulls saved and bred to 20 cows each as yearlings. The top 20 per cent on basis of individual and progeny information returned to serv- ice as 4-year-olds and survivors used natu- rally to 9 years of age. Plan D. .04 of 1 per cent of bulls saved and used artificially without culling, starting at 2 years, on 2,500 cows each per year to 9 years of age. Plan E. .5 of 1 per cent of bulls saved and bred artificially as yearlings to 40 cows each. The top 6yz per cent of these on basis of individual and progeny informa- tion returned to service as 4-year-olds and bred artificially to 2,500 cows per year to 9 years of age. Plan F. .01 of 1 per cent of bulls saved and bred artificially to 10,000 cows each per year starting as 2-year-olds and used to 9 years of age. Plan G. .5 of 1 per cent of bulls saved and bred artificially as yearlings to 40 cows each. The top 2 per cent of these on basis of individual and progeny information returned to service as 4-year-olds and bred artificially to 10,000 cows per year to 9 years of age. The foregoing plans are not necessarily the most efficient which could be devised nor would some of them necessarily be de- sirable or economically feasible from an industry-wide standpoint. They do, how- ever, represent widely divergent plans which will serve to illustrate opportunities for progress through breeding. Bull plans A and C represent what might be accomplished under natural serv- ice with relatively simple plans of mass selection alone or mass selection combined with progeny testing. Bull plans D, E, F, and G represent potentials with artificial insemination used with and without pro- geny testing. With some qualifications to be discussed later, the estimates for possible improve- ment in weaning weight and postweaning gaining ability look very promising. For both these traits it is relatively easy to get information on all animals raised. Taken over a 10-year period, a potential improve- ment of 43 pounds in weaning weight or .43 pounds in average daily gain with even the simplest forms of mass selection repre- sent gains which would in the case of weaning weight represent 10 per cent or more of current averages and for average daily gain 15 to 20 per cent of current averages. The estimates for improvement in effi- ciency of gain are less realistic since they assume complete individual feeding rec- ords on each animal—a procedure seldom, if ever, possible. However, from 2/3 to 4/5 the potential improvement would come from selection of bulls and obtaining individual efficiencies on bulls is not im- possible though costly. Fortunately, rate and efficiency of gain have a high enough relationship for one to be a fairly good indicator of the other. Recent data from State and Federal research in Virginia (J. A. Gaines, unpublished) indicate a saving of approximately 47 pounds of total digestible nutrients per cwt. put on full feed at weaning and fed for a time constant period of 168 to 200 days. If a relationship of this magnitude is a general one, selection for rate of gain will serve to a very considerable extent to effect con- current improvement in efficiency of gain. As can be seen from Table 1, the avail- able heritability estimates for carcass traits are much fewer in number than for the various measures of growth rate and the generally expected values are therefore less well defined. However, calculations are presented for illustrative purposes on pos- sible genetic gains for one commonly used estimator of carcass leanness, rib eye area, and for tenderness as evaluated by the Warner-Bratzler shear. Since to date there are no methods of accurately estimating most carcass traits from live animals, we have assumed that all selection would have to be on the basis of sib and progeny tests. This means that selection intensity and

PRODUCING BEEF ECONOMICALLY 85 genetic progress will necessarily be lower than for traits which can be measured on the animal, itself. Noting the sizes of the estimated genetic gains for carcass traits in relation to sizes of standard deviations will make this point clear. This empha- sizes the need for methods of estimating carcass traits in live animals. Progress can be made without them, but will neces- sarily be slow. The examples given may be useful esti- mates of progress possible in cases where marked deficiencies in one trait make it advisable to select for it alone for a time. Usually, however, concurrent selection will be practiced for several traits. Prog- ress for individual traits will depend upon their heritabilities, the relative emphasis put on each one and on the genetic rela- tionships among them. If equal emphasis is put on selection for each trait and if the traits are genetically independent, progress for any one of n traits should be l/Vn times as rapid for each one as if it were the sole object of selection. Thus, if selec- tion were for four independent traits, progress for any one would be reduced by half. Substantial progress can still be made in selection for several traits at a time but this relationship emphasizes the necessity of keeping the number of items selected for as low as possible if maximum selection pressure is to be put on the im- portant characters. Our knowledge of genetic correlations is still very meager. Koch and Clark (30, 31, 32) studied a large volume of data from Miles City, Montana, on animals raised under range conditions and ob- served negative genetic correlations of un- determined size between maternal abilities of cows and genie values of calves for growth. They also found a small negative genetic correlation of —.05 between gain from birth to weaning and subsequent summer pasture gains of heifers. Carter and Kincaid (7) observed positive ge- netic correlations of .66 and .51 between 182-day weights and subsequent gains of steers and heifers, respectively, when the steers were fed out in dry lot immediately after weaning and the heifers were win- tered to gain 3/4 to I pound daily and their gaining ability evaluated while grazing on bluegrass-white clover pastures during their summer yearling year. Blackwell et al. (2) also observed positive genetic cor- relations between pre- and post-weaning gains. As pointed out by Carter and Kin- caid (7) this relationship may well be in- fluenced by environmental conditions. Indications to date are thus that concur- rent selection for weaning weight and post-weaning gaining ability will be effec- tive for both but it is uncertain whether it will be more or less effective than if they were genetically independent. Studies of data from time constant or weight constant feeding periods have usu- ally shown rather high phenotypic correla- tions between rate and efficiency of gain and Carter and Kincaid (7) found a ge- netic correlation of .32. Thus, improve- ment in rate of gain can be expected to result in improved efficiency. Genetic relationships between produc- tion and carcass traits have not been studied to date but phenotypic relation- ships (6, 7, 46, 47) have in general indi- cated positive relationships between de- sirable production and carcass traits but these have not been high enough to sug- gest they would permit effective use of preslaughter performance data as indica- tors of important carcass traits. On the assumption that they are essen- tially independent genetically, concurrent selection for weaning weight, post-wean- ing gaining ability, rib eye area at a standard weight, and tenderness of lean tissue should in a 10-year period result in increases of 21.5 pounds in weaning weight, .22 pound in average daily post- weaning gaining ability, .14 of a square inch in rib eye area and a decrease of .44 pound in average shear force with the sim- plest mass selection breeding plan. With plans making use of progeny testing and extended use of superior sires through artificial insemination, increases of 44 pound, .35 pound, 37 square inch, and

86 BEEF FOR TOMORROW —1.11 pound, respectively, might well be possible in a 10-year period. Improvements of the magnitude sug- gested for the simple selection schemes would represent improvement of about 5 per cent in weaning weight and would be largely a net increase. The increase of .22 pound in average daily gain would probably be associated with a 6 to 8 per cent saving of feed during a normal fatten- ing period. These gains, while not revolu- tionary or spectacular in any one year are of obvious long time importance. Changes in carcass traits would be in desired direc- tions but would be of lesser magnitude. Increased emphasis on carcass traits should result in a more rapid rate of improve- ment in them but would necessarily mean less intense selection for the production traits and hence less progress for them. The degree of future advances in man- agement practices and/or ability to con- trol the reproductive cycle of the cow will in my opinion determine the extent to which artificial insemination will be used with beef cattle in the future. Its general use could extend the opportunities for se- lection—of that there can be no doubt. We are less sure whether or not the mag- nitude of possible changes would be of the order indicated since slight deviations from normal distributions might markedly affect the selection differentials attainable when very low percentages of sires are se- lected for use. There are also certain in- herent dangers in concentrating too much on relatively few sires. The figures on probable selection effec- tiveness are admittedly theoretical—not yet having been tested in long-time, carefully controlled selection experiments with beef cattle. Looking to other species (16, 33) it is evident that long continued selection for specific traits often, and perhaps usu- ally, results in selection becoming partially or wholly ineffective in spite of apparent existence of hereditary variability. Usu- ally, however, this has occurred only after many generations of selection and after selection has moved the mean several standard deviations in populations not under selection prior to the experiment. The resistance to selection may be due to genie imbalances which result in lowered "fitness" in the selected individuals, to su- periority of heterozygotes, or to other as yet undetermined mechanisms. Looking specifically to meat animals, se- lection for specific traits in sheep has ap- parently been effective as has selection in swine although selection combined with mild inbreeding appeared to have been ineffective or relatively so for many traits. Although not as scientifically rigorous as would be desired, several studies point in the direction of strains of cattle de- veloped with selection for performance characters having superiority in growth rates and efficiency of gain without marked carcass differences as compared to cattle with no background of selection. In Ohio studies (41) the progeny of bulls from two mildly inbred strains with histories of selection for performance traits grew faster and more efficiently and had carcasses of at least equal value as com- pared to progeny of bulls from stocks with no selection background of this kind. Urick and Windecker (43) found that steer progenies of 7 sires resulting from several years of selection for performance in crosses gained an average of .25 pound per day more (and with no overlap in progeny averages) as compared to 7 ran- domly selected groups of steers from "reputation" herds in the area. Carcass data (unpublished information from the above authors) showed only small aver- age differences in items measured but the progenies from selected parents averaged slightly higher in dressing percentage, grades for finish and marbling, and in rib eye area. Scores for conformation were equal. Two experiments (27, 39) have been conducted in which selection for gaining ability was shown to be effective for at least a single generation. To summarize, although we can never be sure of anything until it has been dem- onstrated in practice, there is strong rea- son to believe that consistent selection for

PRODUCING BEEF ECONOMICALLY 87 important items affecting both economy of production and consumer desirability of product will be effective and lead to marked improvement over a period of at least several generations. It should be stressed that genetic improvement tends to be cumulative and permanent and that improvement of even a few per cent in gross efficiency often means a several fold increase in net income. Crossbreeding and Hybridization The term crossbreeding is rather loosely used to include breeding systems involving crosses of two or more pure breeds and systems in which grade or mixed ancestry characterizes part of the parents. Crossbreeding studies among the three British breeds, the Hereford, Angus, and Shorthorn, have been few in number and have given conflicting results. Knapp et al. (28) reported results of a study at Miles City, Montana, in which Shorthorn bulls were bred to Hereford cows, the re- sulting heifers to Angus bulls, and the daughters of this cross in turn to Hereford bulls. The performance of steers and growing heifers of each cross was com- pared with that of high grade Herefords raised in the same year. In this experiment (Table 3) the cross- breds had heavier weaning weights, par- ticularly in the second and third genera- tions, when the crossbreds were out of crossbred cows, faster daily gains on feed test and slightly higher dressing percent- ages and carcass grades. Likewise, cross- bred heifers were heavier at 18 months. The weighted average calf crop was 4.5 per cent in favor of crossbred matings. The favorable results for crossbreeding in this experiment cannot be taken as neces- sarily conclusive since it included only one of the parental purebreds. It is impossible to state definitely whether the good results were due to crossbreeding or to the su- periority of the Shorthorn and Angus sires used. In an Ohio test summarized in Table 4, reciprocal crosses were made between the Angus and Hereford breeds. The cross- breds had lower death losses (5.1 per cent vs. 8.3 per cent) and higher weaning TABLE 3 Results from Crossing Three British Breeds of Beef Cattle* Crossbreds Purebred (Sh. x Here.) Hereford Crossbred (Ang. x Sh. x Here.) Purebred Herefords Crossbred Here, x (Ang. x Sh x Here.) Purebred Herefords Percent calf crop1 92.7 87.6 85.1 75.3 74.5 85.9 Growth of heifer calves: No. 53 55 37 123 14 252 Av. Wean. Wt., Ibs. 393 386 418 378 452 368 Av. 18 mo. wt., Ibs. 776 726 781 705 738 699 Performance of steers No. 57 67 24 91 20 161 Av. Wean. Wt., Ibs. 423 403 440 390 467 388 Feedlot av. daily gain, Ibs. 1.92 1.75 2.00 1.86 2.32 2.10 Final wt., Ibs. 948 879 974 887 1033 912 Gain per 100 lb. TDN, lb. 18.3 18.0 17.4 18.3 18.9 19.0 Av. Dressing % 57.8 56.8 60.1 58.5 59.0 58.0 Av. Carcass Grade Good+ Good Ch- Good+ Ch+ High Good+ Average of two-year results in each generation 1st Generation 2nd Generation 3rd Generation 1 Based on calves weaned in relation to cows bred. * From U. S. Dept. Agr. Circ. 810, 1949.

86 BEEF FOR TOMORROW weights than purebred calves from the same breed of cow. The average gain and dressing percentages of the crossbreds very slightly exceeded the average of the pure- breds while average pounds of total di- gestible nutrients required per cwt. gain and carcass grades were virtually the same. Although the crossbreds in this experi- ment slightly exceeded the average of the purebreds in several regards and were not inferior in any respect, the amount of heterosis was relatively small and could scarcely justify crossbreeding unless the difference in death losses could be shown in experiments of larger scale to be a con- sistent result of crossbreeding. Unfortu- nately, the performance of the crossbred cows as mothers was not tested. Damon et al. (12, 13) made reciprocal crosses between the Angus and Hereford breeds and found no evidence of heterosis in growth rates to slightly over a year of age or in conformation or slaughter grades. Godbey et al. (22) reported re- sults in which crosses between the Angus and Hereford breeds resulted in markedly heavier weights at 210 days of age than for either of the pure breeds but, unfortu- nately, the two purebred cow herds were at different locations and the same bulls did not sire the purebred and crossbred calves. In view of the conflicting evidence, the question of whether enough hybrid vigor can be obtained from crosses among the British breeds to make crossing a feasible procedure must be left as uncertain at present. It is anticipated that experiments now underway will clarify the situation during the next few years. Extensive crossbreeding work, princi- pally in the Southern States, on crossing Zebu type bulls of the American Brahman breed with British type cows has rather consistently shown that as compared to grade or purebred British types the cross- bred calves (1) gain faster to weaning and average 25 to 30 pounds heavier at normal weaning ages of 6 to 8 months, (2) have usually but not always gained some- what more slowly and required more feed per cwt. gain under winter feedlot condi- tions, (3) have gained considerably more rapidly under summer pasture conditions TABLE 4 Eight-Year Summary of Weights, Gain, Feed Efficiency, and Carcass Quality of Purebred Angus, Purebred Hereford and Their Reciprocal Crossbred Calves* Calves from Angus cow Crossbred Calves from Hereford cows Crossbred Purebred Hereford Purebred Angus x Angus x Angus Hereford Hereford No. calves dropped 101 94 104 102 No. calves raised to weaning 91 92 97 94 Av. birth wt., Ib. 59 64 68 65 Av. weaning wt., Ib. at 224 days 382 392 329 353 Av. daily gain on pasture, Ib.1 0.94 0.97 1.08 1.08 Feed lot performance Av. daily gain, lb. 1.62 1.68 1.66 1.68 T.D.N. per 100 Ib. gain., Ib 670 632 599 639 Slaughter data Av. dressing percentage 60.3 60.8 59.7 60.3 Carcass grades Choice 67 77 58 58 Good 22 14 31 35 Commercial 1 2 1 Pasture data 4 years only. * Adapted from Ohio Res. Bui. 703, 1951.

PRODUCING BEEF ECONOMICALLY 89 as yearlings or 2-year-olds, (4) have had advantages of 1 to 4 per cent in dressed yields at slaughter, (5) have averaged about the same in carcass grade when slaughtered as weanling calves but lower when slaughtered at older ages, (6) have produced carcasses differing little in per cent of the various cuts, and (7) when re- tained as brood cows have raised calves usually averaging 75-80 pounds heavier (4,5,8, 12, 13,22,24,35,45). In two experiments (12, 13, 25) in which both Brahman and the parental British breeds have been maintained in the same herds with the same bulls siring purebred and crossbred calves, lifetime growth rates of the crossbred calves have exceeded both parental breeds by consider- able margins. The performance of Brah- man crossbreds is thus one of the best examples of heterosis or hybrid vigor to be found in the animal breeding field. A recent study (Cartwright, unpub- lished) of fertility and calf viability in a Texas herd where Hereford, Brahman, and F, crossbred cows were maintained over a period of years gave the following results: Breed of Percent of Percent of Cow Cows Bred Cows Bred No. Cow Dropping Weaning Years Calves Calves Hereford 765 72.8 65.1 Brahman 244 72.9 54.9 Crossbred H-BR 379 87.6 80.7 Possible effects of heterosis on fertility and calf mortality have been ignored too often in crossbreeding studies. If the above results are representative, these things may be of more importance than other traits studied. The favorable results from Brahman crosses led to the establishment of new breeds based on crossbred foundations. In several tests (Texas Misc. Pubs. 223-F, 258-F, 305-F, 321-F, Flor. Mimeo Rpt. and others) representatives of these breeds have shown excellent performance in cer- tain aspects of productivity but it is still uncertain whether their performance will equal that of first cross animals from par- ents selected for performance. A few recent studies (1; R. A. Damon, unpublished) have indicated that meat from high grade or purebred Brahmans is somewhat lacking in tenderness. In gen- eral that of first-cross animals has been slightly less tender than that from British types but with some evidence of more be- tween sire progeny variability in Brah- mans than in Herefords (9, 10). During recent years there has been in- terest in research with the Charollais breed. In view of the limited number of these animals available in this country, research has thus far been limited to top cross tests. In the two tests conducted to date (12, 13, and unpublished; and Wood- ward et al. unpublished) calves sired by Charollais bulls have grown faster than other types, the carcasses have had higher percentages of lean and less fat but the lean has proved to be about equally ten- der and palatable. Carcass grades have been lower by current standards. For ex- ample, the following results from steers fed in a recent Miles City, Montana, test are striking: It remains to be seen whether these gen erally favorable results with the crossbreds can be duplicated but, if so, present indi- cations are that they may be due, in large part, to hybrid vigor. The most striking indications of hybrid vigor in beef cattle are thus from work involving crosses between British types and two breeds, the Brahman and Charol- lais, of very diverse origins. This suggests the need for intensification of research on disease control and quarantine procedures which will permit the importation of ad- ditional breeds and types of cattle for trials as beef producers in this country particularly for use in test crosses. Several experiments on inbreeding beef cattle in which the lines will eventually be evaluated in crosses are underway but due to their long-time nature very few results are available as yet. Preliminary results from the Colorado Station (40, and Colo- rado Gen. Ser. Pubs. 642 and 683) and the Miles City Montana Station (37) make the performance of crosses of selected in-

90 BEEF FOR TOMORROW Sires Bred to Randomly Selected Groups of Hereford Cows Five Progeny Groups of Herefords Two Progeny Groups of CharoUais x Herefords Group of High Grade CharoUais No. steers 36 14 7 Av. wean, age 186 173 170 Av. weaning wt. 409 454 430 Av. daily gain (252 da. test) 2.34 2.69 2.38 Av. final wt. 999 1137 1034 Av. dressing percent 58.0 58.2 59.3 Av. carcass grade L. Choice H. Good H. Good Av. Composition 9-10-11 rib: % lean 47.1 50.1 53.2 %fat 33.7 30.2 26.4 % bone 19.3 19.7 20.4 Av. shear value1 12.0 12.8 13.9 Av. tenderness rating2 5.3 5.3 5.0 Av. flavor rating2 5.9 5.8 5.7 1 In pounds, with smaller values indicating more tender meat. 1 Subjective panel rating with 7 being most and 1 least desirable. bred lines look promising. It is, however, far too early to more than hazard a guess as to whether performance of crossline and topcross animals will be superior to that which could be expected from populations in which an equivalent amount of effort had been expended in mass selection pro- grams. Summary Direct selection of beef cattle for traits of economic value should be effective and if widely and systematically practiced could potentially improve several traits important in economical production by from 5 to 10 per cent over present aver- ages in a 10 year period. Concurrent im- provement could be made for carcass traits but at a slower rate since most selection for these traits has to be on a sib or prog- eny test basis. Evidence is inconclusive on the amount of hybrid vigor or heterosis which can be expected in crosses among the British breeds of beef cattle but insufficient re- search has been done with these breeds on traits of low heritability relating to fertil- ity and viability which would be ex- pected to be most responsive to cross- breeding. There is marked evidence of heterosis in several traits measuring both growth and fertility in crosses between British and Brahman type cattle and this may be a major factor in the rather widespread use of Brahman crossbred types in certain areas of the South. Preliminary results suggest that heterosis may be important in crosses between CharoUais and British type cattle—also breeds coming from very diverse origins. This general concept em- phasizes the need for intensive research in the disease field to make importations from additional countries possible.

PRODUCING BEEF ECONOMICALLY 91 References 1. Alsmeyer, R. H., A. Z. Palmer, M. Koger, and W. G. Kirk. 1958. Some Genetic Aspects of Tenderness in Beef. J. An. Sci. 17:1137 (Abs.) 2. Blackwell, R. L., J. H. Knox, and C. E. Shelby. 1957. Genetic components of vari- ance and covariance in weaning, yearling and feedlot performance of Hereford steers. J. An. Sci. 16:1018-1019 (Abs.). 3. Brown, C. J. Heritability of weight and cer- tain body dimensions of beef calves at weaning. 1958. Arkansas Agr. Exp. Sta. Bui. 597. 4. Butler, O. D., B. L. Warwick, and T. C. Cart- wright. 1956. Slaughter and carcass char- acteristics of shortfed yearling, Hereford, and Brahman x Hereford steers. J. An. Sci. 15(I):93-96. 5. Carroll, F. D., W. C. Rollins, and N. R. Ittner. 1955. Brahman-Hereford crossbreds and Herefords—Gains, carcass yields and carcass differences. J. An. Sci. 14:218-223. 6. Carter, R. C., and C. W. Kincaid. 1959a. Estimates of genetic and phenotypic param- eters in beef cattle. II. Heritability esti- mates from parent-offspring and half-sib resemblances. J. An. Sci. 18 (1) :323-330. 7. Carter, R. C., and C. M. Kincaid. 1959b. Estimates of genetic and phenotypic param- eters in beef cattle. III. Genetic and pheno- typic correlations among economic char- acters. J. An. Sci. 18(l):331-335. 8. Cartwright, T. C. 1955. Responses of beef cattle to high ambient temperatures. J. An. Sci. 14(2):350-362. 9. Cartwright, T. C., O. D. Butler, and Sylvia Cover. 1958a. Influence of sires on tender- ness of beef. Proc. 10th Res. Conf. Amer. Meat Instit. Foun. March 27-28, 1958, pp. 75-79. 10. Cartwright, T. C., O. D. Butler, and Sylvia Cover 1958b. The relationship of ration and inheritance to certain production and carcass characteristics of yearling steers. J. An. Sci. 17(3):540-547. 11. Damon, R. A., Jr., and Laurence M. Winters. 1955. Selection for factors of performance in the swine herds of the Hormel Founda- tion. ]. An. Sci. (14) (1) : 94-104. 12. Damon, R. A., Jr., S. E. McCraine, R. M. Crown, and C. B. Singletary. 1959a. Per- formance of crossbred beef cattle in the Gulf Coast region. J. An. Sci. 18(1):437- 447. 13. Damon, R. A., Jr., S. E. McCraine, R. M. Crown, and C. B. Singletary. 1959b. Gains and grades of beef steers in the Gulf Coast region. J. An. Sci. 18 (3): 1103-1113. 14. Dickerson, G. E., and L. N. Hazel. 1944. Effectiveness of selection on progeny per- formance as a supplement to earlier culling in livestock. J. Ag. Res. 69 (12) :459-476. 15. Dickerson, G. E., C. T. Blunn, A. B. Chap- man, R. M. Kottman, J. L. K rider. E. J. Warwick, and J. A. Whatley, Jr. 1954. Evaluation of selection in developing inbred lines of swine. Missouri Agr. Exp. Sta. Res. Bui. 551. 16. Dickerson, G. E. 1955. Genetic slippage in response to selection for multiple objec- tives. Cold Spring Harbor Symposia on Quant. Biol. 20:213-224. 17. Dinkel, C. A. 1958. Effect of length of feed- ing period on heritability of post-weaning gain of beef cattle. J. An. Sci. 17:1141 (Abs.) 18. Fine, Neil C., and Laurence M. Winters. 1952. Selection for fertility in two inbred lines of swine. ]. An. Sci. 11 (2):301-312. 19. Fine, N. C., and L. M. Winters. 1953. Selec- tion for an increase in growth rate and market score in two inbred lines of swine. J. An. Sci. 12(2):251-262. 20. Gaines, J. A., R. C. Carter, and C. M. Kin- caid. 1958. Heritability of TDN/cwt. gain in beef cattle that are full fed. J. An. Sci. 17:1143 (Abs.) 21. Gerlaugh, Paul, L. E. Kunkle, and D. C. Rife. 1951. Crossbreeding beef cattle. Ohio Agr Exp. Sta. Res. Bui. 703. 22. Godbey, E. G., W. C. Godley, L. V. Starkey, and E. D. Kyzer. 1959. Brahman x British and British x British matings for the pro- duction of fat calves. S. Carolina Bui. 468. 23. Hetzer, H. O., J. H. Zeller, and R. L. Hiner. 1958. Three generations of selection for high and low fatness in swine. Proc. X Int. Con. of Genetics II:119-120 (Abs.) 24. Hubert, Farris, Jr., E. W. Hoffman, W. A. Sawyer, Ralph Bogart, and A. W. Oliver. 1955. A comparison of Brahma x Hereford crosscreeds with Herefords. Oregon Bui. 549. 25. Kidder, R. W., and Herbert L. Chapman. 1952. A preliminary report of weight per- formances of crossbred and purebred cattle at ihe Everglades Experiment Station from 1943 to 1951. Proc. Assn. South. Agr. Workers, pp. 56-57 (Abs.) 26. Kieffer, Nat M., R. L. Hendrickson, Doyle Stephens, and D. F. Stephens. 1959. The influence of sire upon some carcass char- acteristics of Angus steers and heifers. Oklahoma Agr. Exp. Sta. Misc. Pub. MP- 55:14-19.

92 BEEF FOR TOMORROW 27. Kincaid, C. M., and R. C. Carter. 1958. .Esti- mates of genetic and phenotypic parameters in beef cattle. I. Heritability of growth rate estimated from response to sire selec- tion. J. An. Sci. 17 (3) :675-683. 28. Knapp, Bradford, A. L. Baker, and R. T. Clark. 1949. Crossbred beef cattle for the Northern Great Plains. U.S.DA. Cir. 810. 29. Knox, J. H. 1957. The meat type steer. The interrelations of type, performance and car- cass characteristics. J. An. Sci. 16(1):240- 248. 30. Koch, Robert M., and R. T. Clark. 1955a. Genetic and environmental relationships among economic characters in beef cattle. I. Correlation among paternal and maternal half-sibs. J. An. Sci. 14 (3):775-785. 31. Koch, Robert L., and R. T. Clark. 1955b. Genetic and environmental relationships among economic characters in beef cattle. II. Correlations between offspring and dam and offspring and sire. J. An. Sci. 14(3): 786-791. 32. Koch, Robert M., and R. T. Clark. 1955c. Genetic and environmental relationships among economic characters in beef cattle. III. Evaluating maternal environment. J. An. Sci. 14 (4) :9797-97. S3. Lerner, I. Michael. 1954. Genetic homeo- stasis. John Wiley & Sons, Inc., New York. 34. Lush, Jay L. 1936. Genetic aspects of the Danish system of progeny-testing swine. Iowa Agr. Exp. Sta. Res. Bui. 204. 35. McCormick, W. C., and B. L. Southweli. 1957. A comparison of Brahman crossbred with British crossbred cattle. J. An. Sci. 16(1): 207-216. 36. Neal, P. E. 1946. Corrective sheep breeding. New Mexico Agr. Exp. Sta. Bui. 334. 37. Quesenberry, J. R. 1958. Research at the United States Range Livestock Experiment Station. Montana Agr. Exp. Sta. Cir. 216. 38. Shelby, C. E., R. T. Clark, J. R. Quesenberry, and R. R. Woodward. 1957. Heritability of some economic traits in record of perform- ance bulls. J. An. Sci. 16:1019. (Abs.) 39. Shelton, Maurice, T. C. Cartwright, and W. T. Hardy. 1957. Relationships between per- formance tested bulls and the performance of their offspring. Texas Agr. Exp. Sta. Prog. Rpt. No. 1958. 40. Stonaker, H. H. 1958. Breeding for beef. Colorado Agr. Exp. Sta. Bui. 501-S. 41. Tallis, G. M., E. W. Klosterman and V. R. Cahill. 1959. A topcross breeding experi- ment with outbred and inbred Hereford sires. I. Line comparisons and phenotypic correlations. J. An. Sci. 18 (2) :745-754. 42. Terrill, C. E. 1951. Effectiveness of selection for economically important traits in sheep. J. An. Sci. 10(1): 17-21. 43. Urick, Joseph J., and Claude Windecker. 1959. Beef cattle research. North Montana Branch Station, Havre, (Montana) Mimeo Cir. 1. 44. Wagnon, K. A., and W. C. Rollins. 1959. Heritability estimates of post-weaning growth to long yearling age of range beef heifers raised on grass. J. An. Sci. 18:918- 924. 45. Warwick, E. J. 1958. Fifty years of Progress in breeding beef cattle. J. An. Sci. 17 (4): 922-943. 46. Woodward, R. R., J. R. Quesenberry, R. T. Clark, C. E. Shelby, and O. G. Hankins. 1954. U.S.D.A. Cir. 945. 47. Woodward, R. R., F. J. Rice, J. R. Quesen- berry, R. L. Hiner, R. I. Clark, and F. S. Willson. 1959. Relationships between measures of performance, body form, and carcass quality in beef cattle. Montana Agr. Exp. Sta. Bui. (In Press).

Physiological Factors Affecting the Efficiency of Beef Cattle F. N. Andrews Purdue University Effects of Climatic Factors on Beef Production Competition of Other Beef-Producing Areas At the 1955 Symposium on "Breeding Beef Cattle for Unfavorable Environ- ments" it was emphasized that there are vast areas, especially in the southern hemi- sphere, where beef cattle can be produced. Many of these areas are subtropical or tropical, some are dry and some are wet, and many suffer from alternating wet and dry seasons. In many of these areas the British beef breeds are not well adapted, do not grow or reproduce at normal rates, and may not even survive in the unfavor- able environment. This problem is being overcome by the selection and modifica- tion of native cattle, by the introduction of other breeds, by cross breeding, and by the creation of new breeds. In addition, there are large areas where cattle are well adapted but where feed may be abundant during one season and scarce during another. There are good possibilities of producing feed grains in some of these regions and of introducing cattle feeding systems similar to those of the corn belt in the United States. This may be a question of improved agronomic practices and proper livestock manage- ment. The possibility that the world's meat supply may be considerably ex- panded should not be overlooked. As we overcome climate stresses or modify ani- mals to meet them in the United States, we may expect others to be engaged in the same effort elsewhere, and it may be neces- sary to improve efficiency to meet new competition. The Nature of Heat Stress Homeothermic animals attempt to maintain a constant body temperature. If body temperature fluctuates appreciably the health or productivity of the animal may be affected. Unfortunately, cattle are more efficient in heat production and con- servation than in heat loss. In European breeds of cattle body temperature rises gradually when the environmental tem- perature exceeds 70° F. and increases rapidly at ambient temperatures above 80° F. Zebu cattle show no appreciable increase in body temperature until ambient temperature exceeds 90° F. In most cases the introduction of Zebu blood increases heat tolerance. Rising ambient and rectal temperatures are accompanied by an increased respiration rate. The initial increase in respiration rate may increase heat loss from the animal, but as the heat stress increases the respira- tory muscles may become fatigued and respiration rate declines. In some cases there is an excessive ventilation of the lungs and blood pH is disturbed. Cattle are usually classified as non- sweating animals. However, they do have a primitive type of sweat gland and ap- preciable moisture may be evaporated from the skin. Surface evaporation is an important means of heat loss. It has been shown that moisture loss does in 93

94 BEEF FOR TOMORROW crease with increasing temperature and that Zebu cattle lose more body heat than European breeds, especially at high tem- peratures. In general, an animal with a large sur- face area in relation to body mass has an advantage in heat loss. Some workers have attributed the heat tolerance of the Zebu to the large amount of loose skin and the large appendages. More recent work suggests that animals which are heat tolerant may differ in the efficiency of energy utilization. They may produce less heat per unit of body weight to per- form the various body functions. The Effects of Heat Stress Exposure of animals to the sun, espe- cially during the summer or in tropical regions, imposes a heavy heat load. This has a direct effect on the grazing habits of cattle. European breeds of cattle tend to seek shade at temperatures above 80° F., whereas Zebu cattle or crosses graze in the direct sun and seldom seek shade. Ob- viously, as feed intake is reduced growth rate or milk production decline. Studies at the Missouri Station showed that Short- horn cattle grew more rapidly at 50° F. than at 80° F., Brahma cattle grew as well or better at 80° F., and Santa Gertrudis cattle grew nearly as well at 80° F. These animals were maintained in climatic chambers and the effects are those of tem- perature not complicated by solar radia- tion. There is some difference of opinion as to the role of climate and temperature on reproduction in cattle. High summer temperatures are often accompanied by reduced quantity and quality of forage and decline in summer fertility may result from a combination of factors. However, research with several species indicates that high temperatures may affect spermato- genesis and semen quality and early em- bryonic survival, and, thus, reduce fer- tility. In European breeds of dairy cattle, in- creasing ambient temperatures above 75° F. definitely reduce milk production. Whether lactation is affected by tempera- ture in beef cattle in a normal fluctuating summer environment is unknown, but the possibility exists that reduced summer milk production might affect the growth of calves. Practical Prevention of Heat Stress As pointed out by Ittner et al. (6), 51 per cent of the cattle in the United States are located in areas where the average July temperature exceeds 75° F., and in some regions the daily temperature fre- quently exceeds 95° F. If maximum growth is to be obtained, the decreased feed intake which accompanies rising tem- peratures must be prevented. Ittner et al. (6) published an excellent review of meth- ods of increasing beef production in hot climates. California studies showed that a well designed shade will reduce radiant heat load from the sun and sky more than 50 per cent. Cattle shades should be at least 10 to 12 feet high and the long di- mension oriented East and West. If pro- tected from the sun, cattle may lose con- siderable heat to the sky, since, for ex- ample, when the air temperature was 100° F. the cloud-free sky was 28° F. cooler (2). Shades covered with a heavy layer of hay or straw are very effective in the reduction of solar radiation. Bright metals, not oxidized or rusted, white painted wood or metal, or plastic have all been used successfully. Materials which absorb the radiant energy of the sun and radiate to the animals are undesirable. As shown by the California group, heavy wooden corrals impose a greater heat load on cattle than wire fences. Several ex- periments were carried out to study the cooling of shade surfaces with water. Wetting the lower roof of double roofed shades increased the rate of gain and re- duced respiration rate of cattle (a measure of comfort), but the results were of ques- tionable economic value. The use of water for cooling swine, poultry, and cattle has been the subject of many experiments. The evaporation

PRODUCING BEEF ECONOMICALLY 95 of one gram of water from the body sur- face at 91.5° F. removes 580 calories of heat. If the temperature of the water is less than the surface temperature of the animal, there will be an additional loss of heat due to conduction. In California studies, when water was applied in rela- tively large amounts by a shower nozzle, there was a consistent improvement in rate of gain. The use of mist or fog-type nozzles was not as effective in cattle as the coarser sprays. These types are, how- ever, effective and widely used by swine producers. Itner et al. made extensive studies of the effects of cooling the drinking water of cattle in the desert areas of California. Non-cooled water in this region often has a temperature of 90-100° F. Water cooled to 60-70° F. by mechanical refrigeration or evaporative cooling towers increased daily gain from 0.19 to 0.50 pounds per day. The cattle drank less of the cold water, but the consumption of the cooled water was followed by a reduction in body temperature for several hours. The California group also investigated the role of air movement and air tem- perature on the comfort and performance of cattle. The air may affect both convec- tive and radiation heat exchange and the evaporation of moisture from the body surface. In desert areas evaporative cool- ing of the air is widely used for air con- ditioning homes, greenhouses, and other closed structures. Hereford cattle gained 0.36 pound per day more when they had access to a 3-sided shade cooled by evap- oration, but Brahma-Hereford crosses showed no difference. It was shown that cattle kept in corrals constructed with wire, cables, etc., which allowed unre- stricted air flow gained significantly more than those kept in a heavy wooden corral which affected air flow, and which ab- sorbed and radiated heat to the cattle. The use of fans also increased rate of gain, presumably because increased air movement increased convective heat loss and the evaporation of water from the skin. Research Possibilities Because the climatic environment af- fects growth, reproduction, and lactation of mammals, it is one which merits con- siderable attention. The problem of heat production and heat loss is basically one of thermodynamics. The same principles apply to machines or to living things. Much of the research thus far carried out is basic in nature and deals with the physiology and biochemistry of the ani- mal. The principles of heat production, heat conservation, and heat loss of ani- mals are becoming better understood. There are obvious species differences, breed differences, and possibly strain or family differences. The geneticist and the physiologist are working closely to- gether to develop animals which are heat adapted to particular environments. The intricate relationships of the environment and the endocrine system, the role of the nervous system, the regulation of appe- tite, and the environmental factors in bone, muscle, and fat development are largely unknown. The nutritional requirements of ani- mals in an "average" environment are be- coming better understood, and there is adequate evidence to indicate that during the next decade we must reinvestigate these requirements for each species under different environmental conditions. Practical environmental control is not an art, but the application of basic prin- ciples. The design of a shade for cattle takes into account the four basic methods of heat transfer: radiation, convection, conduction, and evaporation. The appli- cation of these principles at the moment is chiefly a problem of economics. Ani- mals kept in a completely controlled en- vironment regulated for a particular func- tion such as growth, lactation, or egg pro- duction can be expected to improve in performance. The cost of the controlled environment must be more than offset by the increased return from the animal. Heating a brooder or farrowing house is essential in northern climates. The use of properly designed shades and simple

96 BEEF FOR TOMORROW spray cooling systems for swine is be- coming a standard practice. Improve- ments in mechanical heating and cooling systems, the adaption of the heat pump for farm use, the possibilities of using solar energy for both heating and cooling will have a far reaching effect on live- stock production in the future. Problems in Reproductive Physiology Spermatogenesis and Sperm Preservation The success in Russia and Denmark of the practical application of the artificial insemination program initiated by the Russian physiologist Ivanoff in 1899, stimulated American, British, and other scientists to undertake research in sperm physiology. The development of rather simple semen diluters by Phillips and Lardy in 1940 and Salisbury, Fuller, and Willett in 1941 did much to insure the success of artificial breeding in the United States. Several United States workers were able to preserve the motility of sperm frozen at low temperatures but it remained for British workers, Polge et al. 1949, to demonstrate that sperm could be preserved for relatively long periods in the frozen state and remain capable of inducing pregnancy in cattle. These re- searches have been reviewed by Willett (16), Andrews (1), and others. The collection of semen at weekly in- tervals is routine at bull studs throughout the United States; if 10 million motile sperm are used per insemination, sufficient sperm for breeding 50,000 cows per year can easily be obtained. The principle reason for the use of artificial insemina- tion is that it greatly extends the use of proved sires. Under conditions of natural service it is common for a bull to sire no more than 20-30 calves per year. If the bull is of inferior genetic makeup, this is sufficient or even excessive. However, if the bull has been shown to be superior in transmitting ability of milk, growth rate, or meat quality, his limited use is a tragedy. With a few exceptions, most beef cows in the United States are being bred to bulls of unknown transmitting ability, and many of our really good sires are being mated to very small numbers of females. A recent study by Hafs et al. (4) showed that aged dairy bulls are capable of pro- ducing an average of 23.6 billion motile sperm per week. This is sufficient semen for 100,000 cows per year if 10 million motile sperm are allowed per insemina- tion or 200,000 cows if 5 million sperm are used per cow. With present tech- niques for preserving semen, either non- frozen or frozen, it is obvious that we are wasting a great potential in germ plasm. If we believe that livestock improvement depends on the use of proved sires then we must prove more of them in terms of growth rate, feed efficiency, and carcass quality. And having proved them, we must extend their use to the entire cattle population. This is not now being done to the limits of our technical information. Reason for Lag in Artificial Insemination Dairy cattle, whatever the system of management, are closely observed at milk- ing and those which are in estrus can be retained for insemination. Beef cattle kept under farm conditions are usually not closely observed, the facilities for sort- ing and holding them are often poor or entirely lacking, and artificial breeding has been dismissed as impractical. Since the constant availability of frozen semen from outstanding beef bulls, many owners of commercial farm herds have decided that the advantages of using a proved bull outweigh the annoyance of catching the cow. Some employ a new type of gun which fires a tranquilizing drug into the cow and enables the inseminator to per- form without difficulty even under pas- ture conditions. Under range conditions in the United States and other parts of the world where cattle are raised in large numbers, the problem of identifying cattle which are in heat and restraining them for artificial insemination becomes a major under- taking. There has been a long-felt need for a practical method of regulating the reproductive cycle of the cow. If a pre- dictable number of cows could be treated

PRODUCING BEEF ECONOMICALLY 97 so that they would be in heat at a definite time, ovulate and conceive in reasonable numbers, artificial breeding would be widely adopted. The Regulation of the Estrual Cycle The normal estrual cycle and possible means of regulation have been discussed in an excellent review by Hansel (5). The average cow has a cycle 20-22 days in length. Estrus generally lasts 16-20 hours. Both cycle length and duration of estrus may be less in tropical areas. Cattle differ from other farm animals in that ovulation, the release of the egg from the ovary, oc- curs 9-14 hours after heat ends. For- tunately, cattle do become pregnant when inseminated at any time during estrus and even when inseminated prior to ovulation after heat ends. Under practical condi- tions it is preferred to inseminate during the latter part of estrus for maximum con- ception rate. For more than 20 years it has been gen- erally accepted that the development of the ovary, the initiation of estrus, the re- lease of the ovum and the formation of the corpus luteum are under the control of the anterior pituitary gland. It has been believed that the pituitary gland produces two distinct gonad regulating hormones, one called the follicle stimu- lating hormone (FSH) and a second the luteinizing hormone (LH). If this is the case the use of these hormones in proper amounts and in correct sequence should enable us to control the breeding cycle at will. Unfortunately, it has never been possible to accomplish this with any de- gree of regularity in either normal cattle or those which fail to exhibit normal cycles. It is now becoming apparent that the control of the reproductive cycle is more complex than it first appeared. There is good evidence that stimulation of the ner- vous system may initiate the production or release of specific chemical substances which are then transported to the anterior pituitary gland and activate the produc- tion or release of FSH, LH, or other hor- mones. In some species, e.g., the rabbit, copulation initiates a neural mechanism which causes the release of the ovulatory hormone; rabbits do not ovulate spon- taneously. Cattle and other farm animals ovulate spontaneously without the neces- sity of copulation. Several recent studies have shown that neurohumoral substances are involved. It now appears that the hy- pothalamic area of the brain, the posterior pituitary gland, and possibly the adrenal may be involved in addition to the an- terior pituitary gland. Veterinarians have for many years altered the estrual cycle of individual cattle by the removal of the corpus luteum. This requires the manipulation of the ovary by rectal .palpation of the ovary. The corpus luteum produces a hormone, progesterone, which inhibits the initiation of estrus. Removal of the cor- pus luteum relieves the inhibition and the cow comes in heat within a few days. However, only about 25 to 50 per cent of treated cows become pregnant follow- ing treatment. A number of investigators have em- ployed the technique of injecting rela- tively large doses of progesterone. In a recent study by Nellor and Cole (1957) 89 per cent of a group of beef heifers came in heat 15-19 days after a single progesterone injection. However, the conception rate has been below 20 per cent. More research is needed to deter- mine the cause of the low conception rate. Willett (16) reviewed the status of su- perovulation, the production of an un- usually large number of ova in cattle. A large number of treatments involving combinations of FSH, LH, and progester- one have been used. It is clear that cattle can be induced to produce large numbers of ova at a single time, that many of the ova are capable of fertilization, and that fertilized ova may be transferred from one cow to another. However, estrus and ovulation have not been synchronized, many ova are defective and embryonic mortality is high. The control of the estrual cycle would enable beef producers to breed large num-

98 BEEF FOR TOMORROW bers of cattle during a short period of time. It would speed the use of artificial insemination and greatly increase effi- ciency in range areas where large num- bers of cows are ordinarily widely dis- persed. Much basic research must be done before this can be accomplished. The Physiology of Growth This subject was reviewed by Andrews (1). Growth is a complex phenomenon which is influenced by the genetic makeup of the animal, by the hormones of the anterior pituitary, thyroid, and adrenal glands, and by the ovarian and testicular hormones. Growth rate is profoundly affected by nutritional status, parasites, and disease. We must now concern ourselves not only with the rate of growth, but the nature of growth in terms of bone, muscle, and fat and in the efficiency of growth. Basically, we would prefer to improve growth by genetic means, in the hopes of fixing and perpetuating those factors which are related to it. Since we have only limited means of recognizing de- sirable genetic makeup, we must concern ourselves with the possibilities of altering growth in other ways. As early as 1943 Lorenz showed that the implantation of diethylstilbestrol would increase fat deposition and improve car- cass quality in chickens. Purdue studies between 1946-1949 showed that the im- plantation of diethystilbestrol in cattle and sheep produce true growth stimula- tion. It is now recognized that several estrogenic substances, diethylstilbestrol, hexestrol, dienestrol, and estradiol will increase muscle growth in cattle and sheep and do not increase fat deposition as in chickens. It has long been recognized that males grow more rapidly than fe- males. This is apparently due to the effects of the testicular hormone, testoster- one. There are a large number of sub- stances in the male hormone group (androgens). The androgens have strong anabolic effects and bring about nitrogen retention and protein formation. Many experiments involving androgens have been carried out. They will, at proper levels, promote growth in cattle and show promise for reducing fat deposition in swine. While the androgens are produced by chemical synthesis, the cost of produc- tion remains high, especially in compari- son with diethylstilbestrol and its deriva- tives. Perhaps one of the most striking effects of the estrogenic compounds on the growth of ruminants is the improved feed efficiency which accompanies the increased growth rate. The use of estrogen has found wide acceptance among cattle feed- ers and it is estimated that about 80 per cent of all beef-type cattle are either im- planted with or fed estrogens. Approxi- mately six different products are now available commercially for cattle. The principal growth regulating hor- mone is produced by the anterior pitui- tary gland and is called the growth hor- mone. It has been known since 1921 but thus far has been confined to investiga- tional use. The growth hormone is a protein, is very difficult to isolate, would be extremely difficult to synthesize, and must be injected frequently to produce a response. There is good evidence that animals differ genetically in growth hor- mone secretion rate. If a means of esti- mating growth hormone levels in the live animal could be devised, it might be pos- sible to more effectively select for rapid growth. Research of this type is under- way in several laboratories. The thyroid gland is involved in growth, especially of the young animal, and it is also concerned with energy re- quirements, reproduction, milk, and egg production. In some of the lower species the thyroid is necessary for metamor- phosis. Prior to the widespread use of iodized salt, subnormal thyroid function (goiter) limited or prevented swine and sheep production in many areas of the United States. There is good evidence in cattle that reduced thyroid activity may be a limiting factor in high milk produc- tion. Materials are commercialy available for the correction of lowered thyroid func-

PRODUCING BEEF ECONOMICALLY 99 tion but their practical use in cattle has been limited. Theoretically, a controlled reduction in thyroid activity should reduce metabolic rate, reduce feed requirements, and stimu- late fattening. A large group of com- pounds, goitrogens, is available for such purposes. As early as 1940 it was shown that partial removal of the thyroid would increase fattening in cattle for short periods of time, and that the use of goitro- gens would increase gain or improve feed efficiency for short periods. In recent years highly potent goitrogens have been used in cattle feeding and may be bene- ficial under certain conditions. One of the areas which is of consid- erable current interest is the role of plant hormones on the animals which consume them. The first effects were essentially bad. In Australia subterranean clover may contain sufficient estrogenic hormone to cause excessive mammary and genital development of sheep, serious prolapse of the vagina or rectum, and sterility. It is known that certain legumes, including alfalfa and ladino clover, may have ap- preciable estrogenic activity. It has been theorized that a portion of the growth promoting or lactation stimulating effects of forage may be hormonal in nature. It has been demonstrated that some legume hays will increase growth rate in sheep and cattle (1). There are very great dif- ferences in the estrogenic activity of alfalfa samples. The variability may be related to stage of growth, season, en- vironmental factors, and genetic makeup of the plant. Purdue studies involve the selection of alfalfa for both high and low estrogenic activity. It would appear that we have only be- gun to understand the regulation of growth. The determination and selection of animals with genetotypes related to endocrine makeup, the development of new materials for growth regulation, and the development of feeds and forage with desirable hormonal activity have real pos- sibilities in livestock improvement. References 1. Andrews, F. N. 1958. Fifty years of progress in animal physiology. J. An. Sci. 17:1064. 2. Bond, T. E., C. F. Kelly, and H. Heitman. 1958. Improving livestock environment in high temperature areas. J. Hered. 49:75. 3. Findlay, J. D. 1950. The effects of tempera- ture, humidity, air movement and solar radiation on the behavior and physiology of cattle and other farm animals. Hannah Dairy Res. Inst. Bui. 9. 4. Hafs, H. D., R. S. Hoyt, and R. W. Bratton. 1959. Libido, sperm characteristics, sperm output and fertility of mature dairy bulls ejaculated daily or weekly for thirty-two weeks. J. Dairy Sci. 42:626. 5. Hansel, W. 1959. The estrous cycle of the cow. Chap. 7. Reproduction in domestic animals. Academic Press, New York. 6. Ittner, N. R., T. E. Bond, and C. F. Kelly. 1958. Methods of increasing beef produc- tion in hot climates. California Agr. Exp. Sta. Bui. 761. 7. Johnson, H. D., A. C. Ragsdale, and R. G. Yeck. 1958. Effects of constant environ- mental temperatures of 5O" and 80° F. on the feed and water consumption of Brah- man, Santa Gertrudis and Shorthorn calves during growth. Missouri Agr. Exp. Sta. Res. Bui. 683. 8. Johnston, J. E. 1958. The effects of high temperatures on milk production. J. Hered. 49:65. 9. McDowell, R. E. 1958. Physiological ap- proaches to animal climatology. J. Hered. 49:52. 10. Phillips, R. W. 1949. Breeding livestock adapted to unfavorable environments. FAO Agr. Study I. 11. Rhoad, A. O. 1955. Breeding beef cattle for unfavorable environments. Univ. Texas Press. Austin, Texas. 12. Roubicek, C. B., R. T. Clark, and O. F. Pahnish. 1957. Range cattle production. 8. Effects of climatic environment. Arizona Agr. Exp. Sta. Rep. 154. 13. Shrode, R. R. 1958. Breeding considerations in relation to climatic problems. J. Hered. 49:80. 14. Ulberg, L. C. 1958. The influence of high temperature on reproduction. J. Hered. 49:62. 15. Warwick, E. J. 1958. Effects of high tempera- ture on growth and fattening in beef cattle, hogs and sheep. J. Hered. 49:69. 16. Willett, E. L. 1956. Developments in the physiology of reproduction of dairy cattle and in artificial insemination. J. Dairy Sci. 39:695.

Some Nutritional Factors Involved in Beef Production J. H. Meyer University of California, Davis EFFICIENT meat production from beef cattle requires the sound application of nutritional principles derived from ex- perimental investigations with not only beef cattle but many other animal species. Most principles of nutrition have de- veloped from research with laboratory and farm animals other than cattle and can be applied directly or indirectly to beef cattle production. The symbiotic re- lationship between the ruminant and the microflora of the rumen, however, is always in the background influencing the nutrition of cattle. Digestion and utiliza- tion of cellulose is the most important result of this relationship. Furthermore, it is becoming apparent that we can, by various feeding regimes, influence the end products of microbial digestion. These may influence feed intake, body compo- sition, milk composition and, as a result, feed evaluation, and utilization. The purpose of this paper, therefore, is to re- view certain areas in nutrition which de- serve emphasis in considering the produc- tion efficiency of beef cattle. The reader is referred to the fine review by Riggs on Beef Cattle Nutrition in the 50th An- niversary issue of the Journal of Animal Science for information on areas not covered in this paper. Ruminant Digestion The reticule-rumen is a favorable en- vironment for the rumen microflora (1, 2, 3). Not only does the ruminant provide adequate substrate (food and water) for microbial activity but it also removes end- products (fatty acids) and disposes of non- digested substrate into the rest of the ali- mentary canal. In return, the microflora digests cellulose (4, 5) which provides volatile fatty acids as an energy source for the ruminant. This gives the rumi- nant a unique advantage over meat ani- mals with simpler stomachs and makes available food (beef) for human consump- tion not otherwise available from fibrous feeds. As a further service to the host, the microflora synthesize amino acids and vitamins which can be utilized by the ruminant (6). This markedly decreases the number of nutrients needed in cattle rations. Carbohydrate Utilization Fiber Roughages are classed as such because they are high in fibrous compounds- cellulose, hemicellulose, and lignin. A re- cent review on this subject has been made by Hansen et al. (7). The evidence ade- quately presented by Baker and Harris (8) shows that ruminants use cellulose be- cause the rumen microflora secrete cellu- lases to digest the cellulose. Fatty acids, resulting from this process, are then ab- sorbed and utilized by the host (9, 10, 11). Much research effort has been made on methods of enhancing fiber digestion but it has become apparent that lignin is the most important factor influencing rough- age digestion (11, 12, 13, 14). Not only is lignin unattacked but the depressing effect on cellulose digestion of various roughages seems to result from lignin pre- venting the action of microbial cellulose enzymes. More recently, Salsbury et al. (15) have shown that holocellulose, free from lignin and isolated from roughages 100

PRODUCING BEEF ECONOMICALLY 101 of varying digestibilities, was equally utilized by isolated rumen microorgan- isms. Quicke and Bentley (16), using similar techniques, concluded that cellu- lose digestibility was related to lignin content in timothy but not in brome or orchardgrass. Nevertheless, when their data were combined and recalculated, the correlation of cellulose digestibility and ash-free, acid-insoluble lignin was —0.90. Meyer and Lofgreen (17) have shown a very high correlation between lignin and total digestible nutrient content of alfalfa. Moreover, further work with growing lambs showed a high correlation (—0.94) between weight gains and lignin content (18). Recent reviews (19, 20, 21) point out that much of the physiology and chemistry of lignin is being solved. Nord and Schu- bert (21) have presented a scheme for synthesis of and a structural formula for lignin. Pigden (22) points out that lig- nin affects the curing properties of grasses. He also showed histologically that the progress and site of lignification were not similar in the grasses he studied. Meyer et al. (18) showed that the effect of lignin differed in the utilization of alfalfa and oat hay by sheep. Apparently roughages are utilized best when fed to animals being maintained rather than fattened (23, 24). Roughages, especially those higher in crude fiber, have relatively higher heat increments (23, 24) than concentrates. This heat would be useful to beef cattle maintained at low environmental temperatures even though it would be useless at critical tempera- tures or above, and would be particularly harmful at high environmental tempera- tures (25). Armstrong et al. (26, 27) have presented information to indicate that the heat increment produced by various proportions of volatile fatty acids not apparent at levels below maintenance is found with fattening sheep. Acetic acid is largely responsible for the heat increment effect in fattening and a de- crease in heat increment occurs when the proportion of propionate is raised. Since the research of Phillipson (28), others (29-32) have verified that roughages result in the production of a higher pro- portion of acetate by rumen microorgan- isms while concentrate additions increase the proportion of propionate. Roughages can vary from poor-quality feeds such as rice hulls, practically worth- less as a feed, to high-quality pasture ap- proaching a fattening ration in quality. Utilization of roughage can be considered from two standpoints: first, and possibly the most important, is how can a feed such as pasture or hay be managed to make it the highest quality commensurate with greatest economic yield? Second, if the production of the feed cannot be manipulated to improve quality, how can it be used to obtain the most nutritive value? Pasture. Sound pasture or range man- agement must consider requirements of the plant as well as the animal. Few fields of research involve such careful consideration of plant-animal relation- ships that is required in grazing manage- ment. Cultivated pastures can vary in the production of quality and quantity of livestock feed by varying the plant species (33, 34), stocking rate (35), method used for grazing (35, 36, 37), grazing frequency (34), and intensity of grazing (38). In addition, lack of water, length of day and growing season are important factors. The grazing animal has an influence be- cause he can select the highest quality feed available (34, 38). For example, Weir and Torell (39) showed that grazing sheep select from a grass range a feed con- taining substantially more protein and less fiber than that found in hand-clipped samples from the same area. As the sea- son progressed and the forage became sparse, the animals were not able to se- lectively graze because they had already selected the most nutritious feed. Mc- Meekan (35) has a particularly good dis- cussion on the effects of stocking rate. Heavy stocking rates may cut down on rate of gain but meat production per acre increased because the animals were forced

102 BEEF FOR TOMORROW to consume more of the lower quality forage. There is much research to be done to develop principles of pasture utilization and then apply them to the many conditions that exist. Management to obtain a consistent supply of feed from pasture or range is one of the greatest problems confronting a beef operator. Periods of lush feed supply or periods of shortages are gen- erally operating, with the irrigated pas- ture or the pasture in adequate rainfall areas, or, in other words, quantity and quality of feed available per day are never consistent. Because of this, the most criti- cal management problem is adjusting ani- mal numbers to obtain the greatest eco- nomic production per acre commensurate with optimum daily gain. In most areas, spring and early summer periods have adequate available forage, while late sum- mer and autumn are periods of short feed supply. If one stocks a field for the for- mer, then the feed supply is short in the latter period and gains or body con- dition drop. Hay or concentrates should be fed or animal numbers decreased. It cannot be overemphasized enough that this area of pasture maagement is too often overlooked. On the other hand, too much forage in the spring creates a man- agement condition often ignored. If there is too much forage, the more palatable, nutritious species are over- grazed, and coarse, more undesirable plants increase. Cutting some pasture for hay or judicious clipping after grazing would be in order. On the other hand, the main problem on the range or pastures in inadequate rainfall areas are the seasons when little or deficient feed is available. Additional nutrients (energy, protein, phosphorus, and/or vitamin A) are generally supplied by supplements (40, 41). This is expen- sive and cattle are too often in poor con- dition because this was neglected. Hay and Silage. Forages are harvested to provide a source of feed during winter seasons, to provide feed when it is de- sirable to feed cattle in a dry lot, or to provide feed to other areas. Hays and silages are among the most variable of harvested feeds. Not only are there great variations between species, but even greater variation sometimes oc- curs within a species. When hay is placed in the same federal grade, great differences in response are found. For ex- ample, Moore (42) reports that alfalfa hays, graded U. S. No. 2, produced daily gains which varied from 0.84 to 1.62. After attention to such management practices as seed-bed preparation, irriga- tion and weed removal, the first control a cattleman has over hay quality is se- lection of the species. Swift et al. (43) have suggested and embarked on a pro- gram of determining the nutritive value of single forage species at different ma- turity stages. This is a sound step towards choosing the highest quality species. Then if mixtures of forages are used, feed- ing value can be calculated according to the proportion of the various species. The second step over which control can be exercised is the proper stage of ma- turity for highest yield of nutrients. The best time for cutting is difficult to de- termine. Reid et al. (44) point out that in the Northeast the digestible dry mat- ter (Y) can be accurately predicted from days elapsing from April 30 (X), Y = 85.0—0.48X. This gives a simple method of predicting quality. Also they suggest dry matter content as a simple indicator of nutritive quality. Meyer et al. (18) have shown that height of alfalfa is a possible indicator of quality. The production of the highest quality forage for hay is not always the most eco- nomical time for harvest because yield of dry matter would be down. Conversely, yield of dry matter is not the best criteria because quality might be so low that net yield of available nutrients would be down. This was also pointed out by Reid et al. (44). Additional evidence by Meyer et al. (45) showed that even though dry matter yield of oat hay was highest at the milk stage, greatest yield as measured by

PRODUCING BEEF ECONOMICALLY 103 meat production was in the flower or dough stage. Examples of important work in this area have been conducted by Forbes and Garrigus (46), Dawson et al. (47), and Kivimae (48). Even though high-quality forage is cut, this does not guarantee that high-quality forage will be fed to the cattle. Weather conditions, method of harvesting, and method of storage often dramatically de- crease forage value. Dehydration (49, 50), barn drying (51), ensiling (49, 50, 52, 53, 54), and mechanical treatments to speed drying such as hay crushers (51) can often be used to save nutrients. One of the most comprehensive studies was that made by Shepherd et al. (55) Barnett (56) has an excellent discussion on silage. Pelleting hay is a relatively recent method of handling and feeding hay. When hay is finely ground and pelleted, feed consumption increases and results in a greater daily gain (57, 58). Little prac- tical difference seems to occur in digesti- bility (57, 59). Possibly there will be a great future for pelleted hays because bulk reduction improves the ease of handling, storage, and reduces feed refusals. Some caution is needed in the acceptance of pelleting because high-concentrate rations are not always well utilized as pellets (60). Furthermore, parakeratosis of rumens from lambs fed pelleted feed has been reported as a serious problem (61). Use of large pellets or wafers of coarsely- chopped or long hay are also possibilities for a means of packaging hay (62). Generalizations are difficult to make re- garding the method of choice for harvest- ing and preserving forage for cattle feed because of the many economic considera- tions. Nevertheless, yield should be meas- ured in terms of the particular nutrients needed rather than dry matter and the most inexpensive "sure-fire" method used for harvesting. Poor-Quality Roughages. Roughages are classified in this category primarily because they are high in lignin and cel- lulose, lignin being the predominate rea- son. As pointed out earlier, not only is the absolute quantity of lignin impor- tant, but probably the site of deposition is as important. The lignin content of poor- quality roughages varies between 12 and 20 per cent (7). Cellulose digestibility by rumen microorganisms in poor-quality roughages was as high as that from alfalfa when lignin was removed. A very successful research effort was that of Burroughs, Gerlaugh, and associ- ates (63-65) in demonstrating that corn cobs can be well used in cattle rations if missing nutrients are supplied. Beeson and Perry (66) developed a supplement which successfully satisfies the nutritional deficiencies of many poor-quality rough- ages. Others have studied poor-quality prairie hay (67) and cotton gin trash (68). There is a great need to re-evaluate these and other poor-quality roughages when properly supplemented for maintenance, wintering, or fattening through the use of the net energy principle. Starch Large quantities of starch from grains, particularly during fattening, are con- sumed by cattle. The rumen microflora, as with cellulose, seem to be necessary for starch utilization by the ruminant. Es- den and Phillipson (5) point out that very little starch reaches the lower gas- trointestinal tract, and that little amylase has been found in the saliva of ruminants (8) Moreover, Larsen et al. (69) have presented data to indicate little starch breakdown in the small intestine. More confirmatory data are needed in this area. Even though the ruminant is uniquely prepared to utilize roughage, the feeding of large quantities of cereal grains is an economical practice. Many times concen- trates are much the cheaper source of energy for fattening ruminants and make up the largest proportion of the ration. Some years ago Mead and his co-workers (70, 71) raised dairy heifers and bulls to four years of age on rations devoid of roughage. Growth was satisfactory but some problems occurred with bloat and other digestive disturbances. The Na- tional Research Council (72) has suggested

104 BEEF FOR TOMORROW that a certain minimum of crude fiber be in fattening rations. The need of a cer- tain amount of fiber, however, has not been proved. If such work is done, con- stituents other than crude fiber should be the criteria. Use of roughage per se as a standard for comparison in concentrate- roughage ratio studies is unfortunate. A precise description of the roughage quality in terms of chemical constituents is needed; lignin and cellulose might be best. Although rates of gain are some- times equivalent over a wide range of con- centrate-roughage ratios, a certain amount of concentrate is needed to obtain opti- mum fat laydown (73, 74). Lofgreen et al (75) showed though little differences existed between daily gains of steers fed high-roughage rations and those fed higher levels of concentrate, a higher energy content occurred in the weight gain of those fed concentrate because of a higher fat content. Nitrogen Utilization The protein nutrition, of ruminants is unique, interesting, and of great practical value in the ultimate production of high- quality protein for human consumption. The rumen microflora play an integral role because all nitrogenous substances must pass through the rumen and micro- organisms utilize much of the nitrogen from feedstuffs for synthesis of their own characteristic protein (6, 11, 76). There is a tendency, therefore, for the biological values (absorbed protein utilized by the animal) of proteins to approach a com- mon value because much of the dietary protein is converted to microbial pro- tein. McDonald (77, 78) has shown that 40 per cent of zein and 90 per cent of casein were degraded in the rumen and utilized for the synthesis of microbial pro- teins and clearly demonstrated a differ- ence between proteins in their progress through the tract. Even though most workers (79-82) have found that most com- mon feed proteins were similar in value, higher biological values were found for blood fibrin and whole egg protein and lower values for gelatin and urea as a pro- tein source. Explanations for these dif- ferences may be in the proportion con- verted to microbial protein (77, 78) or loss of ammonia from rapid protein de- gradation in the rumen (83, 84). Huffman (11) points out that legumes are abundant sources of protein for ruminants but it is becoming clear that research is needed on how best to utilize legume proteins. Some years ago Turk et al. (85) had shown that the biological value of alfalfa protein could be raised by adding carbohydrate to the ration. Re- cently Meyer et al. (57) confirmed the re- ports of Gray and Pilgrim (86) that there is a great loss of nitrogen from an all- alfalfa hay ration before reaching the abomasum. Presumably the nitrogen from alfalfa was lost as ammonia (83, 84) because Annison (87) has reported little amino acid absorption from the rumen. It has been realized for many years that non-protein nitrogen was utilized by ruminants (88) but conclusive proof was offered by Loosli et al. (89) showing amino acid synthesis from diets with urea as the main nitrogen source. The excellent re- view of Reid (88) brings out the optimum conditions needed for maximum urea utilization as a source of protein. A low level of true protein and a high level of starch favor urea utilization. Sugars and cellulose are inferior to starch. Sugars disappear too rapidly from the rumen and cellulose is too slowly available. It ap- pears that urea satisfactorily replaces up to 25 per cent of the protein equivalent in a ration containing 11 to 13 per cent protein equivalent. Vitamin Needs A most important peculiarity of rumi- nants (6) is the synthesis of the B-complex vitamins and vitamin K by the rumen microflora. Being synthesized in the fore- part of the digestive tract allows maxi- mum absorption and is a second impor- tant peculiarity (90). Moreover, there is no clearly-defined demonstration that sup- plements of B-vitamins to cattle with well- developed rumens improved growth, re- production, or ration digestibility (91).

PRODUCING BEEF ECONOMICALLY 105 The demonstration of value, need, and requirement of vitamin A by Guilbert and Hart (92), proved an important adjunct to cattle feeding. Under usual conditions of management where cattle are exposed to sunlight or consume sun-cured hay, ad- ditional vitamin D has not been shown necessary. Vitamin E has been shown to be required by cattle (93) but the defi- ciency could only be produced on solvent- extracted rations. Reproduction prob- lems were by no means an important symptom of an E-deficiency (94). An im- portant aspect of vitamin E nutrition was demonstrated by Muth et al. (95), show- ing that selenium might be important in white muscle disease of sheep. An inter- action of selenium and vitamin E had previously been shown with rats and chickens (96). Nutrient Requirements No discussion on requirements is neces- sary since the National Research Council Requirements have recently been revised (72). Some recent work on energy re- quirements by Winchester (97) and Gar- rett et al. (98) should be mentioned, how- ever. Some discussion on factors in- fluencing requirements might be in or- der. Maintenance "The energy cost of maintenance is the net dietary energy required to keep the organism in a 'steady' energetic state—the net dietary energy required to replace the energy expended while carrying on 'maintenance' life processes. . . ." (99). According to the estimates of Axelsson and Eriksson (100), 95 per cent of the metabolizable energy is used to maintain the body while only about 5 per cent is required for development of the fetus of a pregnant animal. Even in periods of growth the maintenance requirement is about 66 per cent, on an average. There- fore, the energy cost in beef production is largely one of the maintenance need. Breeding heifers at one year of age rather than at two years of age is one example of saving maintenance costs (101). Con- tinuous growth of beef cattle on the range (40) or maintaining rapid gains in the feedlot are also good examples. Main- tenance energy requirement can be con- sidered a constant overhead cost. Efficient beef production, at all stages of the life cycle, should keep this cost as low as possible. Three important factors influence the maintenance requirement for energy: basal metabolism, activity, and environ- mental temperature. The major mainte- nance energy expense is for basal metabo- lism, varying from about 50 to 85 per cent (99). The animal with no activity, consuming no food and producing no product requires a certain quantity of energy to maintain life processes. Periods of low feed or energy intake will lower the basal metabolic energy production (103, 104), and the low basal metabolic rate will continue for a period of time even after refeeding at a luxuriant level. This is probably one of the explana- tions for the steers of Winchester and Howe (105), restricted in feed intake for a period of time, making as efficient gains as those continuously full-fed their rations, even though the restricted steers were fed for a longer period of time. These data are not necessarily in conflict with those of Guilbert et al. (40) because Guilbert's steers were restricted in growth on the range by energy, protein, phos- phorus, and vitamin A deficiencies, while Winchester's animals were restricted in energy or protein (106). The energy an animal must expend in the activity of obtaining feed is part of the maintenance requirement. No doubt the range animal must use more energy for this activity than the animal fed in a small pen in the feedlot. Lofgreen et al. (107) have shown that steers spend more time grazing in search of feed than when fed green feed in a small feedlot. It seems desirable to keep animal activity at a minimum for maximum production. There is practically no information on the energy required for various activities of beef cattle while feeding. Conversely, no

106 BEEF FOR TOMORROW conclusive data exist that some exercise is desirable. The energy required to keep warm is also a maintenance need but the environ- mental temperature at which the net energy of feed is used for this process is quite low (99). There is little informa- tion about the magnitude of the effects of wind, rain, or snow on energy needs. Armstrong et al. (108) have begun studies with sheep along these lines. Protein needs during maintenance are largely those of replacing the loss of metabolic nitrogen in the feces of cattle fed high-fiber roughage such as that found on the range (109). Winchester et al. (106) have made some estimates of the di- gestible protein requirement of cattle held at a maintenance level of energy intake. Apparently digestible protein require- ments should include consideration of the energy intake (106) and the indigestible fiber intake (109). Indigestible fiber in- creases fecal loss of nitrogen. With the exception of vitamin A, little is known of the maintenance needs by cattle for other nutrients. Growth and Fattening Body Composition. The young beef animal contains more water and less fat than the mature steer (110) and the growth process can be roughly considered as one of dilution of the ash, protein, and water with fat. Moulton et at. (1ll, 112) showed that the first weight gains of a calf contain about 10 per cent fat while the gains contain 90 per cent fat at 3 to 4 years of age. While the proportion of water to protein to ash changes as the animal ages, their proportion remains relatively constant compared to the pro- portion of fat to these constituents (110). Callow (113) emphasizes that the level of fatness is the major factor in the per- centage of muscular tissue. More information is needed on the effect of nutrition on carcass composition. Means are at our disposal to more easily study carcass composition as influenced by feeding. Kraybill et al. (114) have pre- sented data which demonstrates the ease of water and fat determination from spe- cific gravity of the carcass. We have found this method easy to apply (98); all that is required is weight of carcass in air and under water. The excellent paper of Reid et al. (110) presents many addi- tional equations for the application of such data. Rate of Gain. The genetic make-up of an animal has a limiting effect on rate of gain. Environmental factors, which in- clude nutrition, can be used to influence rate of gain. The first factor to be con- sidered is feed intake. The general problem in human nutri- tion is one of lowering food intake (115) while we in Animal Husbandry are in- terested in maximum feed intake. It is well accepted that the more an animal eats the more he gains. The data of Baker et al. (116) can be used to demon- strate the correlation of feed intake and daily gain. This correlation was 0.91, while a non-significant —0.07 existed be- tween dry matter digestibility and daily gain. A further example of the impor- tance of food intake by beef cattle is furnished by Black et al. (73) when car- cass grade was found to be highly corre- lated with feed intake (r = 0.72). It therefore behooves the beef man to be vitally interested in feed intake and know all the "why" about it. The series of pa- pers on food intake presented to the New York Academy of Sciences is well worth reading (117-121). The neural regulation of food intake (119) is an area deserving investigation. Damage to certain areas of the hypothalamus causes an increased food intake of such animals as the rat and dog, but so far this has been unsuc- cessful with sheep at California (122). Feed preparation has an influence on feed intake. Fine grinding and pelleting of hay increases feed intake and hence, weight gains (57, 58, 123). The main con- cern in feed intake is one of energy in- take, and the addition of concentrates in- creases energy intake. This is a well- known fact of cattle fattening.

PRODUCING BEEF ECONOMICALLY 107 Rate of gain decreases during the later phases of fattening, primarily due to an increased fat content in the gain (111), but maintenance needs also increase because of increased size. The gain of energy, however, may be as great or greater, but the apparent gain decreases. Discussions by Willey et al. (124) and Knox and Roger (125) indicate that type may or may not influence rate of gain. This type of research is difficult because one is never certain that the types com- pared are representative of populations. Selection for certain strains within a "type" for rapid rate of gain might be possible. However, both Gerlaugh and Gay (126) and Durham and Knox (127) agreed that feeder grade did not seem to be associated with subsequent gain. Measurement of Gain. One of the big sources of error in any comparison of nu- tritional treatments is that associated with weighing conditions. For example, Balch and Line (128) report that over 84 per cent of the weight change of cows when changed from winter feeding to grazing was rumen fill. Recent studies (129, 130) emphasize the value of (10- to 15-hour) periods without feed and water before cattle are weighed in order to reduce vari- ation. Koch (129) further suggests that much of the variation due to fill could be reduced by three weighings with several days between weighings. Hubbert (131) showed that, even with a 12-hour stand without feed and water, fluctuations occur for three weeks and that weights of beef cattle immediately following periods of stress should be used with caution. It seems that for best results a 12- to 15-hour stand without feed and water is the mini- mum necessary for accurate estimations of weight gains. Furthermore, the cattle should be adjusted to feed and environ- mental conditions before experimental weights are taken. It is common to express results in dairy cow experiments in terms of fat-corrected milk. Should we not be thinking along terms of the production of "fat-corrected carcasses" when we speak of nutritional effects in beef cattle? Not only would this correct for rumen fill, taking into account differences in fat content, but would also represent the end economic product. Representative animals could be killed at the beginning of an experiment to obtain initial fill and fat content de- termined by specific gravity. Gain in "fat- corrected carcasses" could be calculated by difference. Another possibility would be to use the final carcass weight corrected to a common fat content as the final measurement in an analysis of covariance with initial weight as the independent variable. This corrects the carcass for variation of initial weight of the steers. Accurately defined weighing conditions, of course, would be necessary. Efficiency of Gain. Many, many vari- ables enter into this term when expressed as gain per unit of feed consumed or feed required per 100 pounds of gain. In reality these terms are apparent expres- sions of efficiency of feed utilization be- cause one variable is expressed in terms of another variable (gain and/or feed in- take). The first factor affecting these terms is the net available energy in the feed. The higher energy rations, higher in concentrate, usually produce the most gain per unit of feed consumed. Sec- ondly, the energy content of the gain affects these expressions of apparent effi- ciency of feed utilization. Weighing con- ditions, as discussed earlier, would have an influence since the fill in the gastroin- testinal tract would vary depending on how the animals were handled. This fill would create large errors if assigned to gain in weight. Fat content in the gain would have an influence. A low fat content in the gain would make an animal appear more effi- cient if gain per unit of feed consumed were the expression of efficiency of gain. The following data were calculated from the paper of Garrett et al. (98): Note that when fat content in the gain increased, the relative value of rations 2 and 3 compared to ration 1 was less when calculated from gain per 100 pounds feed

108 BEEF FOR TOMORROW Fat content Gain per 100 Energy gain of the lb. feed per 100 Ib. weight gain consumed feed consumed % of % of Ration % lb. ration 1 meal, ration 1 1 17.8 6.9 100 8.1 100 2 30.1 9.0 141 15.0 185 3 32.9 10.6 154 20.0 247 consumed than calculated from energy gain per 100 pounds feed consumed. This point is illustrated more vividly by Lof- green and Otagaki (132) when practically equal gains in weight occurred per 100 pounds of feed consumed, 10.1 and 10.2, but the energy gain per 100 pounds of feed consumed was 21.9 and 25.9 meal, because fat in the gain was 41.3 and 51.5 per cent respectively. Age, maturity, and size would influence feed required per unit of gain because the more mature animals have a larger proportion of fat in their gain. The older, larger animals would appear more inefficient; one important reason for the decrease in apparent efficiency of feed utilization as a fattening period nears the end. This gross efficiency measurement of energy utilization is closely related to physiologic age (99). In addition, the older animal is larger and a larger pro- portion of the feed is needed for main- tenance requirement. MacDonald (133) made calculations from a theoretical study of the energy cost of beef production. He suggested that the lowest calory cost per pound of body weight, while varying with rate of gain and calving percentage, is produced at a body weight of 850 to 1,100 pounds. He did not consider body composition but this is probably satisfactory if we agree that protein production is one of the main purposes of beef production. Reproduction and Lactation The primary functions of adult cattle in the beef herds are reproduction and lactation. Most of the nutrient require- ment is for maintenance. Bulls need extra nutrients, primarily an energy source, for the extra activity during breed- ing season, while cows have the nutrient requirement for the developing fetus and milk production. Jakobsen (134) and Jakobsen et al. (135) in two very fine papers present information on the pro- tein and energy requirement. Earlier, Reid (136) discussed the relationship of nutrition to fertility. Even though there are reports (137) that the lactating ability of the beef cow makes a major contribution to the growth of the calf, little direct evidence can be found on requirements during lactation of the beef cow. Wallace (138), in some studies on the effect of level of nutrition on the growth of lambs before and after birth, showed that 96 per cent of the variation in weight gains from birth to 112 days is due to differences in consump- tion of milk and supplements by lambs. He also presents a great deal of informa- tion to show the effects of level of nutri- tion on the vigor of the lamb and dam at birth. Much more information is needed in this vital field of beef cattle nutrition. Undoubtedly the first experiments should be conducted in pens where accurate rec- ords of feed consumption can be kept; then applications can be made to the pasture and the range. Here, level of nutrition could be a very fruitful field of research. Feed Evaluation Recently, Blaxter (23) presented evi- dence in a comprehensive review to the effect that use of the net energy principle is superior to total digestible nutrients (TDN) in evaluating feeds. TDN over- evaluates poor-quality roughages and/or underevaluates high-quality roughages and concentrates. TDN, digestible en- ergy or metabolizable energy does not take into account energy lost as heat in- crement (energy lost as heat as a result of consumption of food). Heat increment is much higher for roughages. The Na- tional Research Council recently used digestible energy as one means of express- ing energy requirements. The digestible

PRODUCING BEEF ECONOMICALLY 109 energy values of the feeds, however, were calculated from the previously deter- mined TDN. Garrett et al. (98) have, among others, shown that digestible or metabolizable energy was not any more accurate than TDN as a measure of food energy. It was realized in this study that digestible energy is simpler to determine and a definite physical unit. Measurement of the energy value of feeds for ruminants, therefore, will not be greatly improved unless a system uti- lizing the net energy principle is used to evaluate feeds. If it is agreed that net energy is the most satisfactory means of evaluating feeds, then a move to a system using the net energy principle might be called for. Mistakes would be made, but I do not hesitate to predict that this would stimulate much needed research in this area. The system has been used in Europe in a satisfactory manner, and is therefore workable. It is true that more data are needed on various feeds; data are needed, no doubt, on each feed for various levels of production and for vari- ous physiological functions. Morrison's Feeds and Feeding (139) gives actual and estimated values for many feeds and thus supplies a start in this direction. Kleiber (24, 140) has suggested that a Replacement Equivalent system similar to the Scandinavian Feed Unit be used to evaluate feeds. This involves using two feeds such as corn and soybean meal and/or barley and cottonseed meal as standards, replacing them with the feed to be evaluated to produce the same en- ergy gain. This system uses the net en- ergy principle and has the additional value of conducting determinations on feeds under conditions similar to the way cattle are generally fed. Corrections could be used to refine the method by estimat- ing carcass composition from specific gravity. This system utilizes experiments from which monetary returns would be realized and therefore would not be ex- pensive. We have used a similar system in calculating feed value (37, 57, 98, 132); it was workable and checked well with animal response and Morrison's values for net energy (139). A master project involving several experiment stations on a national basis would be a suitable ap- proach. At first, experimental procedures would need to be worked out, refined, and applied. Study of the effects of levels of feeding and purpose for which the energy is needed would logically follow. Then feeds could be evaluated as easily as in digestion trials. Chemical analysis would add to the precision of feed evaluation. Mitchell (141) suggested that use of chemical an- alysis for a precise constituent would add materially to the usefulness of digestible energy or nutrients in evaluating feeds. Walker and Hepburn (142) demonstrated the usefulness of crude fiber or lignin by regression equation to predict digestible energy content of mixed grass hays. Crude fiber was more useful than lignin. Later work (143) with grass silages showed lignin to be the best indicator of quality. Meyer and Lofgreen (144) have devised a system of evaluating alfalfa hay by an analysis for crude fiber. Both TDN and digestible protein were predicted from the crude fiber analysis. Furthermore, replacement values in terms of barley and cottonseed meal could be calculated. Previously, Walker and Hepburn (142, 143) utilized a similar idea by estimating the starch equivalents of their hays and silages from chemical analysis. Summary The symbiotic relationship between ruminants and the rumen microflora is one of the most important factors affect- ing the production efficiency of beef cat- tle. Utilization of cellulose from fibrous feeds by the microflora provides fatty acids as energy sources for the ruminant.

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112 BEEF FOR TOMORROW 61. Jensen, R., J. C. Flint, R. H. Udall, A. W. Deem, and C. L. Seger. 1958. Parakera- tosis of the rumens of lambs fattened on pelleted feed. Am. J. Vet. Res. 19:277. 62. Jones, I. R., B. F. Magill, and R. G. Peter- son. 1958. Baled, wafered and pelleted hay: comparative feeding values for milk production. Oregon Agr. Exp. Sta. Bui. 63. Burroughs, W., P. Gerlaugh, A. F. Schalk, E. A. Silver, and A. E. Kunkle. 1945. Nutritive value of corn cobs in beef cattle rations. J. An. Sci. 4:373. 64. Burroughs, W., P. Gerlaugh, B. H. Edging- Ian, and R. M. Bethke. 1949. Further observations on the effect of protein upon roughage digestion in cattle. J. An. Sci. 8:9. 65. Burroughs, W., and P. Gerlaugh. 1949. The influence of soybean oil meal upon roughage digestion in cattle. J. An. Sci. 8:3. 66. Beeson, W. N., and T. W. Perry. 1952. Balancing the nutritional deficiencies of roughages for beef steers. J. An. Sci. 11:501. 67. Gossett, J. W., and J. K. Riggs. 1956. The effect of feeding dehydrated alfalfa meal and trace minerals to growing beef calves fed poor quality prairie hay. J. An. Sci. 15:840. 68. Erwin, E. S., and C. B. Roubicek. 1958. The utilization of cotton gin trash by growing and fattening steers. ]. An. Sci. 17:133. 69. Larsen, H. J., G. E. Stoddard, N. L. Jacob- sen, and R. S. Allen. 1956. Digestion and absorption of various carbohydrates posterior to the rumino-reticular area of the young bovine. J. An. Sci. 15:473. 70. Mead, S. W., and W. M. Regan. 1931. De- ficiencies in rations devoid of roughage for calves. I. The effect of the addition of cod liver oil and alfalfa ash. J. Dairy Sci. 14:283. 71. Mead, S. W., and H. Goss. 1935. Ruminant digestion without roughage. J. Dairy Sci. 28:163. 72. Burroughs, W., M. L. Baker, W. P. Garri- gus, T. B. Keith, G. P. Lofgreen, and A. L. Neumann. 1958. Nutrient require- ments of beef cattle. Nat'l. Acad. of Sci.— Nat'l. Res. Coun. Pub. 579. 73. Black, W. P., P. E. Howe, J. M. Jones, and F. E. Keating. 1943. Fattening steers on milo grain in the S. Great Plains. U.S.D.A. Tech. Bui. 847. 74. Dowe, T. \V., V. H. Arthaud, and J. Matsu- shima. 1955. Ratio of concentrates to alfalfa hay in fattening rations for beef cattle. Nebraska Agr. Exp. Sta. Bui. 431. 75. Lofgreen, G. P., J. H. Meyer, and N. R. Ittner. 1959. The effects of time and level of supplementation on beef steers fed alfalfa soilage or hay. J. An. Sci. (In Press). 76. McNaught, M. L., and J. A. B. Smith. 1947. Nitrogen metabolism in the rumen. Nutr. Abst. Rev. 17:18. 77. McDonald, I. W. 1954. The extent of con- version of food protein to microbial pro- tein in the rumen of sheep. Biochem. J. 56:120. 78. McDonald, K. W., and R. J. Hall. 1957. The conversion of casein into microbial proteins in the rumen. Biochem. J. 67:400. 79. Ellis, W. C., G. B. Garner. M. E. Muhrer. and W. H. Pfander. 1956. Nitrogen utilization by lambs fed purified rations containing urea, gelatin, casein, blood fibrin and soybean protein. J. Nutr. 60:413. 80. Lofgreen, G. P., J. K. Loosli, and L. A. Maynard. 1947. The influence of pro- tein source upon nitrogen retention by sheep. J. An. Sci. 6:343. 81. Williams, V. J., and R. J. Moir. 1951. Ruminal floral studies in the sheep. III. The influence of different sources of nitro- gen upon nitrogen retention and upon the total number of free microorganisms in the rumen. Aust. J. Sci. Res., Series B, Biol. Sci. 4:377. 82. Johnson, B. C., T. S. Hamilton, W. B. Robinson, and J. C. Garey. 1944. On the mechanism of non-protein-nitrogen utilization by ruminants. J. An. Sci. 3:287. 83. Chalmers, M. I., D. P. Cuthbertson, and R. L. M. Synge. 1954. Ruminal ammonia formation in relation to the protein re- quirement of sheep. I. Duodenal ad- ministration and heat processing as fac- tors influencing fate of casein supplements. ]. Agr. Sci. 44 (3) :255-273. 84. Chalmers, M. I., and R. L. M. Synge. 1954. Ruminal ammonia formation in relation to the protein requirement of sheep. II. Comparison of casein and herringmeal supplements. J. Agr. Sci. 44 (3) :263-269. 85. Turk, K. L., F. B. Morrison, and L. A. May- nard. 1934. The nutritive value of the proteins of alfalfa hay and clover hay when fed alone and in combination with the proteins of corn. J. Agr. Res. 48:555. 86. Gray, F. V., and A. F. Pilgrim. 1956. Di- gestion of nitrogenous compounds by ruminants. Nature 178:94. 87. Annison, E. F. 1956. Nitrogen metabolism in the sheep. Protein digestion in the rumen. Biochem. J. 64:705. 88. Reid, K. T. 1953. The urea as a protein replacement: a review. J. Dairy Sci. 36:955. 89. Loosli, J. K., H. H. William, W. E. Williams, W. E. Thomas, F. H. Farris, and L. A. Maynard. 1949. Synthesis of amino acid in the rumen. Science 110:44.

PRODUCING BEEF ECONOMICALLY 113 90. Kon, S. K., and J. W. G. Porter. 1947. The synthesis of vitamins in relation to re- quirement. Nutr. Abst. Rev. 17:31. 91. Head, M. J. 1953. The effect of quality and quantity of carbohydrate and protein in the ration of sheep on the digestibility of cellulose and other constituents of the ration with a note on the effect of adding vitamins of the B-complex on the digesti- bility and retention of the nutrients of a hay ration. J. Agr. Sci. 43:281. 92. Guilbert, H. R., and G. H. Hart. 1935. Minimum vitamin A requirements with particular reference to cattle. J. Nutr. 10:409. 93. Gullickson, T. W., L. S. Palmer, W. L. Boyd, J. W. Nelson, F. C. Olson, C. E. Calverley, and P. D. Boyer. 1949. Vitamin E and nutrition of cattle. I. Effect of feeding vitamin E for rations on reproduction, health, milk production and growth. J. Dairy Sci. 32:495. 94. Blaxter, K. L., and F. Brown. 1952. Vita- min E in the nutrition of farm animals. Nutr. Abst. and Rev. 22:1. 95. Muth, O. H., J. E. Oldfield, J. R. Schubert, and L. F. Remmert. 1958. Effects of selenium and vitamin E on white muscle disease. Science 128:1090. 96. Anonymous. 1958. Vitamin E and selenium. Nutr. Rev. 16:149. 97. Winchester, C. F. 1953. Energy require- ments for maintenance and growth. U.S.D.A. Tech. Bui. 1071. 98. Garrett, W. N., J. H. Meyer, and G. P. Lof- green. 1959. The comparative energy re- quirements of sheep and cattle for mainte- nance and gain. J. An. Sci. 18:528. 99. Brody, S. 1945. Bioenergetics and growth. Reinhold Publishing Corp., New York. 100. Axelsson, J., and S. Eriksson. 1953. Energy requirements for maintenance of domestic animals. Ann. Royal Agr. College Sweden, 20:51. 101. Albaugh, R., and H. T. Strong. 1955. Breeding yearling beef heifers. California Agr. Exp. Sta. Ext. Service Cir. 433. 102. Kleiber, Max. 1947. Body size and meta- bolic rate. Physiol. Rev. 27:511. 103. Marston, H. R. 1948. Energy transactions in the sheep. Aust. J. Sci. Res. 1:93. 104. Horst, K., L. B. Mendel, and J. G. Benedict. 1934. The influence of previous diet, growth and age upon the basal metabolism of the rat. J. Nutr. 8:139. 105. Winchester, C. F., and Paul E. Howe. 1955. Relative effects of continuous and inter- rupted growth on beef steers. U.S.DA. Tech. Bui. N.I 108. 106. Winchester, C. M., R. L. Hiner, and B. C. Scarborough. 1957. Some effects on beef cattle of protein and energy restrictions. J. An. Sci. 16:426. 107. Lofgreen, G. P., J. H. Meyer, and J. L. Hull. 1957. Behavior patterns of sheep and cattle being fed pasture or soilage. J. An. Sci. 16:773. 108. Armstrong, D. G., K. L. Blaxter, N. McC. Graham, and F. W. Wainman. 1959. The Effect of environmental conditions on food utilization by sheep. An. Prod. 1:1. 109. Blaxter, K. L., and H. H. Mitchell. 1948. The factorization of the protein require- ments of ruminants and on the protein value of feeds, with particular reference to the significance of the metabolic fecal nitrogen. J. An. Sci. 7:351. 110. Reid, J. T., G. H. Wellington, and H. D. Dunn. 1955. Some relationships among the major chemical components of the bovine body and their application to nutritional investigations. J. Dairy Sci. 38:1344. 111. Moulton, C. R., P. N. Trowbridge, and L. D. Haigh. 1922. Changes in chemical com- position on different planes of nutrition. Missouri Agr. Exp. Sta. Res. Bui. 55. 112. Moulton, C. R., P. N. Trowbridge, and L. D. Haigh. 1922. Changes in propor- tion of carcass and offal on different planes of nutrition. Missouri Agr. Exp. Sta. Bui. 54. 113. Callow, E. H. 1948. Comparative studies of maintenance. II. Changes in the carcass during growth and fattening and the rela- tion to the chemical composition of the fatty and muscular tissue. J. Agr. Sci. 38:174. 114. Kraybill, H. F., H. L. Bitter, and O. G. Hankins. 1952. Body composition of cattle. II. Determination of fat and water content from measurements of body specific gravity. J. Applied Physiol. 4:575. 115. Mayer, Jean. 1955. The physiological basis of obesity and leanness. Nutr. Abst. and Rev. 25:597. 116. Baker, J. P., R. W. Colby, and C. M. Lyman. 1959. The relationship of feed efficiency to digestion rates of beef cattle. J. An. Sci. 10:726. 117. Quigley, J. R. 1955. The role of the di- gestive tract in regulating the ingestion of food. Ann. N. Y. Acad. of Sci. 63:7. 118. Mayer, J. 1955. Regulation of energy in- take and body weight: the glucoctatic theory and the lipostatres hypothesis. Ann. N. Y. Acad. of Sci. 63:15. 119. Brobeck, J. R. 1955. Neural regulation of food intake. Ann. N. Y. Acad. of Sci. 63:44. 120. Janowitz, H. D., and J. Hallander. 1955. The time factor in the adjustment of food intake to varied caloric require- ment in the dog: a study of the precision of appetite regulation. Ann. N. Y. Acad. of Sci. 63:56, Reprint 248.

114 BEEF FOR TOMORROW 121. Grossman, M. I. 1955. Integration of cur- rent views on the regulation of hunger and appetite. Ann. N. Y. Acad. of Sci. 63:76. 122. Smith, J. D., M. T. Clegg, and W. F. Ganong. Unpublished observations. Univ. of Calif., Davis. 123. Meyer, J. H., W. C. Weir, J. B. Dobie, and J. L. Hull. 1959. Influence of the method of preparation on the feed value of alfalfa hay. J. An. Sci. 18:976. 124. Willey, N. B., O. D. Butler, J. K. Riggs, J. H. Jones, and E. J. Lyerly. 1951. The in- fluence of type on feedlot performance and killing qualities of Hereford steers. ]. An. Sci. 10:195. 125. Knox, J. H., and M. Roger. 1946. Com- parison and gains in carcasses produced by three types of feeder steers. J. An. Sci. 5:331. 126. Gerlaugh, P., and C. W. Gay. 1935. Rela- tive efficiency and profitableness of three grades of feeder steers. Summary of four years. Bi-mo. Bui., Ohio Agr. Exp. Sta. 20:38. 127. Durham, R. M., and J. H. Knox. 1953. Correlation between grades and gains of Hereford cattle at different stages of growth and between grades at different times. J. An. Sci. 12:771. 128. Balch. C. C., and C. Line. 1957. Weight changes in grazing cows. J. Dairy Res. 24:11. 129. Koch, R. N., E. W. Schleicher, and V. H. Arthaud. 1958. The accuracy of weights and gains of beef cattle. J. An. Sci. 17:604. 130. Whiteman, J. B., P. F. Loggins, D. Chambers, L. S. Pope, and D. F. Stevens. 1954. Some sources of error in weighing steers off grass. J. An. Sci. 13:832. 131. Hubbert, F., Jr. 1955. The comparison of trucking and trailing beef cows and calves to and from summer ranges. J. An. Sci. 14:279. 132. Lofgreen, G. P., and K. K. Otagaki. 1959. The net energy of blackstrap molasses fed at three levels to fattening steers. J. An. Sci. (In Press). 133. MacDonald, M. A. 1957. Slaughter weight of beef cattle for theoretical maximum energetic efficiency. N. Z. J. Sci. Technol. (A) 38:706. 134. Jakobsen, P. E. 1956. Protein require- ments for fetus formation in cattle. 7th International Congress of Animal Hus- bandry, Reprint 353. 135. Jakobsen, P. E., P. H. Sorensen, and H. Larsen. 1957. Energy investigations as related to fetus formation in cattle. Acta Agr. Scand. 7:103, Reprint 352. 136. Reid, J. T. 1949. Relationship of nutrition to fertility in animals. J. Am. Vet. Med. Assoc. 114:158-164; 242-250. Reprint 54. 137. Rollins, W. C., and H. R. Guilbert. 1954. Factors affecting the growth of beef calves during the suckling period. J. An. Sci. 13:517. 138. Wallace, L. R. 1948. Growth of lambs be- fore and after birth in relation to the level of nutrition. J. Agr. Sci. 38:93, 243, 367. 139. Morrison, F. B. 1956. Feeds and Feeding. Morrison Publishing Co., Ithaca, New York. 140. Kleiber, Max. 1959. Symposium on forage evaluation. II. Progress in feed evalua- tion. Agron. J. 51:217. 141. Mitchell, H. H. 1942. The evaluation of feeds on the basis of digestible and metabolizable nutrients. J. An. Sci. 1:159. 142. Walker, D. M., and W. R. Hepburn. 1959. The nutritive value of roughages for sheep. I. The Relationship between gross digestible energy and chemical com- positions of hays. J. Agr. Sci. 45:298. 143. Walker, D. M.. and W. R. Hepburn. 1956. The nutritive value of roughages for sheep. II. The relationship between the gross di- gestible energy and the chemical composi- tion of silages. J. Agr. Sci. 47:172. 144. Meyer, J. H., and G. P. Lofgreen. 1959. Evaluation of alfalfa hay by chemical analysis. J. An. Sci. (In Press) .

Management Systems and Production Efficiency in Beef Cattle Robert C. Kramer Michigan State University Management Systems Bradford and Johnson (1) in their farm management book categorize beef cattle fattening into 13 systems. These 13 sys- tems were set up by farm management re- search workers from the North Central states in the early 1950's. They are: Group I. Fall purchase of 400-pound calves System A—1. Begin October 15 at 400 Ibs. 2. Full feeding, dry lot 3. End at 1,000 1bs. System B—1. Begin October 15 at 400 Ibs. 2. Winter on roughages 3. Full grain feeding on pasture 4. End at 1,000 Ibs. System C—1 and 2. Same as in System B 3. Pasture with no grain during first half of graz- ing season 4. Grain during last half of pasture period 5. Finish in dry lot at 1,000 Ibs. System D—1 and 2. Same as in Systems B and C 3. Pasture with no grain during grazing season 4. Fatten in dry lot for 90- 100 days 5. End at 1,000 Ibs. System E—All-roughage system 1. Begin October 15 at 400 Ibs. 2. Winter on pasture and dry roughages 3. Pasture with no grain during grazing seasons and sell Group II. Purchase of 650-pound (me- dium to low grade) feeders System F—1. Begin in April or May at 650 Ibs. 2. Full grain feeding on pasture System G—1. Begin same as for System F 2. Pasture with no grain during grazing season 3. Fatten in dry lot System H—1. Begin October 15 at 650 1bs. 2. Winter on roughages 3 and 4. Same as 2 and 3 in System G Group III. Purchase of 650-pound (high- good to choice) feeders System I—1. Begin April or May at 650 Ibs. 2. Full grain feeding on pasture System J— 1. Same as in System I 2. Pasture with no grain during grazing season 3. Fatten in dry lot System K—1. Begin October 15 at 650 1bs. 2. Winter on roughages 3 and 4. Same as 2 and 3 in System J Group IV. Purchase of two-year-olds System L— I. Begin October or No- vember at 800 Ibs. 2. Fatten in dry lot 115

116 BEEF FOR TOMORROW 3. Finish to (a) medium to low-good; (b) high-good to choice System M— 1. Begin April or May at 800 Ibs. 2. Fatten with grain on pasture 3. Same as in System L There are literally hundreds of systems of producing cattle. You will immedi- ately agree that the 13 fattening systems mentioned do not include 1) the calf producing systems, 2) the commercial and custom beef feeding operations, 3) the use of feed additives and growth stimu- lants, or 4) the assumption of changed breeding habits of beef females. You will also note that these 13 beef fattening systems are tied closely to the apron strings of Mother Nature. Re- member how often the fall months of October and November and the spring months of April and May were men- tioned. A decade ago more feeder cattle were placed on feed in these four months than is true today. There is much less seasonality in the placement of cattle on feed and consequently less seasonality in the slaughter of fed cattle. I shall refer to this again but want to point out that the packing and distribution sectors of the beef economy desire less seasonality than now exists. One of the more systematic approaches to research in beef production was re- ported in U.S.D.A. Technical Bulletin 900, entitled "Relation of Feed Consumed to Food Products Produced by Fattening Cattle," by Aaron G. Nelson (2). Even though this bulletin is 14 years old, it provides many guide lines for research in this area. Several different types of research have been done: Smith (3) re- ported on a linear programming analysis in a beef cattle feeding program; Hog- lund (4) analyzed feed substitutes for beef production; and Stangeland (5) reported on input and output relationships in live- stock production. There is a family of reports on feeding trials from a majority of the Agricultural Experiment Stations in the United States (6). A new addition is usually added to each family each year (7). The research- ers test new ideas so that those which prove useful can be adopted in the in- dustry. These reports on cattle feeding show the weight gains which can be ob- tained by feeding rations which are bal- anced, are high in energy, and are sup- plemented with hormones, biologicals, chemicals, or tranquilizers. Or, they show how economically gains can be achieved on rations with high roughage contents. These reports represent a sample of the research work which has been done on the subject of producing beef. Valuable data have been published, but I would raise this question: Do the social sci- entists know about all the research of the animal scientists and do the animal scientists know about the research of the social scientists? I believe there are many opportunities for interdisciplinary coop- eration in designing feeding experiments and interpreting research results. Regardless of the exact number of sys- tems used to produce beef, the industry has made progress as noted in the July 1959 issue of Agricultural Situation (8). Harold Breimyer wrote: "The cattle industry has made great strides in productivity. Production of beef per animal on farms is almost a half higher now than 30 years ago. "This record is the more remarkable because the cow, unlike the sow and ewe, seldom has multiple births. One calf per cow each year is the usual limit. This is a handicap to increases in pro- ductivity. "Rising productivity of the cattle herd has helped beef output in the United States to double since the 1920's. Only half of that increase is attributa- ble to more cattle on farms. The other half is due to their higher productivity. "Cattle numbers on farms have in- creased no faster than the human popu- lation in the last 30 years. But because more beef is produced per animal, beef output has outrun population, enabling

PRODUCING BEEF ECONOMICALLY 117 consumption per person to increase 25 per cent. "Lacking the advantage of multiple births, the bovine's greater productivity comes about in other ways. Trends since the early 1920's illustrate six of these. "1. More of all cattle are beef cattle. The percentage of beef-type cattle in the herd has been rising since 1939 (from 47 per cent to 67 per cent today). Although dairy cattle also produce beef, they don't do so quite as well as beef cattle. "2. A higher percentage of all beef cattle are cows. Among cattle kept for beef, the proportion of cows has risen from less than 35 per cent before 1940 to about 40 per cent today. "This is not so meaningful in itself. But it does reflect how much the pro- portion of steers and heifers has de- creased, as they are raised faster now than formerly. In the 1920's steers often were held until they were 3 or 4 years old, and each one appeared in the inventory that many times. Now most steers are slaughtered before they're 30 months old [a few before they are 12 months old—and they weigh over 900 pounds, too]. "3. The calving rate is higher now. Multiple births are still rare, but more cows now have one calf. The number of calves born per 100 cows has in- creased from 75-80 in the mid-1920's to 85-90 in the last few years. "4. More calves are raised to matu- rity. Until 1940 about 40 per cent of all calves were slaughtered as calves, and 60 per cent as mature cattle. In 1958, only 29 per cent were slaughtered as calves, and 71 per cent as mature cattle. More feedlot feeding, and im- proved breeding have speeded this trend. "5. Death loss has been reduced. Since 1924 the percentage death loss has declined a fifth. "6. Finally, average dressed weights of cattle slaughtered have increased [about 80 pounds per head]. There may be some question as to whether so much heavier weights are desirable. Insofar as they are associated with im- proved type, little objection can be raised. At times, too many over-fat cattle have been marketed. In any event, when weights are heavier more beef is produced per animal." When we compare beef with other com- modities, we can rightly raise the question about the speed of adoption of innova- tions which will be needed to keep beef competitive. Byerly (9) reported that the increase in production per head of beef and veal increased 18 per cent from the 1925-29 period to the 1951-55 period. This compares with increases of 25 per cent for pork, 53 per cent for eggs, and 118 per cent for chickens. These data show that beef cattle have increased pro- duction per unit slower than other red meat competitors and only one-sixth as fast as chickens. The 1958 annual report of the Ralston Purina Company (10) says that it took nearly 11 pounds of feed to produce one pound of beef in 1930. Today it takes around 7.5 pounds. In 1930 the average daily gain was two pounds; today it is nearly three pounds per head. USDA researchers writing in the 1959 Outlook Chart Book (11) said, "With the striking exception of broilers and turkeys, the average amount of livestock products produced per pound of concentrates has not changed greatly in the last 20 years." On the surface there seems to be a contradiction in these reports. This points up a prime requisite for all of us in this industry. We must be sure to define the terms clearly and we must use comparable statistics. And we have sta- tistical problems in this industry, as Ives (12) ably states: "Our statistical difficulties arise mainly from the twin facts (a) that cattle are not produced and marketed as an annual crop, and (b) that we are not dealing with a single, homogenous commodity. Instead, the production

118 BEEF FOR TOMORROW process can be as short as a few weeks, as in the case of veal calves, or as long as 8 or 10 years, in the case of cows culled from breeding herds. In be- tween these two extremes is the bulk of our beef supply which goes through various degrees of feeding and which may take as little as 90 days or as much as 12 months or longer. Furthermore, this finishing process may begin at vari- ous stages of maturity, and the result- ing beef can differ widely in its quality factors." In addition, we need to exercise cau- tion when we use the statistics dating back to the 1920's. Another factor we need to consider is that our plant breeders, our soil nutri- tionists, and our agricultural engineers have provided knowledge which enables land to produce more feed per acre and for animals to obtain more T.D.N. and vitamins per ton through improved varie- ties, improved growing, and improved handling of pastures and roughages. We need also to recognize the large body of facts which have been uncovered about the use of feed additives, minerals, implants, and tranquilizers. Most tests prove that these reduce costs of gain, speed gains, and cut down death losses (13). But if they are used and we compare the results with research data from earlier years, we are not comparing the efficiency of feed conversion per se nor the produc- tion efficiency of beef cattle in an earlier period with the same beef cattle in the latter period. New variables have been added and they should be recognized. Increases in productivity have come, as stated above, from advances in feeding, breeding, and in disease and parasite con- trol. If we examine the area of beef breeding, here are some of the things we find. Three-fourths of the states now have performance testing programs. Pro- fessor J. H. Knox (14) reported that "most production traits have heritabili- ties from 30 to 50 per cent. This means as much as one-fourth of the superiority of the parent may be expected in the off- spring if selection is applied to one parent only and about twice this amount if ap- plied to both parents." Knox further reported that some performance testing is done to locate the best animals in a region or the nation and the herds or lines of breeding from which they come. In other cases the purpose is to help the owner find more productive animals in his own herd and develop plans for using them after he finds them. Many states are publishing bulletins on the performance tests in their herds (15). Breed associations are also testing and reporting their results. Typical of a num- ber of releases from breed associations and testing programs was the release from the American Hereford Association on June 22, 1959, reporting gain results of a pair of Hereford bulls owned by breeders in Utah. The release said, "Top animal in the gain program gained 3.02 pounds per day during the 105-day test. The bull required only 5.25 pounds of feed to put on one pound of gain in comparison to the average of 6.41 pounds of feed re- quired by the 30 bulls in the Utah State University program." The Performance Registry International has registrations in 33 states and 2 foreign countries (16). The USDA has its own performance program and individual ranchers and farmers check the performance of their herds. Mr. George F. Ellis, Manager of the Bell Ranch in New Mexico, (17) WTOte: ". . . It is true that we have been following the breeding program at Bell Ranch for the past eleven years de- signed to increase the efficiency of our cattle. In that time, we feel that we have gotten very good results. We have been able to increase our calf weaning weights about fifty (50) pounds. At the same time, we have increased the grade of our cattle re- markably. When we began we only had 9 per cent calves which would grade fancy. For the past three (3) years we have had sixty (60) per cent of better fancy calves."

PRODUCING BEEF ECONOMICALLY 119 I am sure that breeding experiments have increased productivity of beef ani- mals. However, the 50-pound increase at the Bell Ranch probably was obtained from a combination of better care, better disease control, better feeding, as well as better selection and breeding. Rapid advances have occurred in re- search dealing with the breeding of ani- mals. Swine researchers have discovered how to regulate the oestrus cycle of gilts and sows. By using their research it will soon be possible to breed an entire herd of sows on the same day. Since boar semen cannot be diluted as can bull semen and freezing ruins boar semen, the ability to control the oestrus cycle is a significant technical breakthrough for the swine industry. A decade of research has been con- ducted on the regulation of the oestrus cycle in beef cows. Dr. John Nellor at Michigan State, who has developed a method for controlling the ovulation of sows and who has also worked with the oestrus cycle in cattle for 10 years, re- ported to the writer that several hurdles remain to be crossed in connection with beef cows (18). Let's assume Nellor and his colleagues are someday successful with cows. This will permit an expanded use of artificial insemination in beef cow herds, particu- larly in the Western states. If all cows can be treated so that their oestrus cycles can be controlled, then artificial insemi- nation with semen from bulls with desir- able traits will be much more practical. Size of Operations There are approximately 3.5 million cattle producers in the United States. This number includes the very small and the very large producers. The number of producers has been decreasing and the size of the average operation has been increasing. These trends will continue as specialized knowledge becomes more important for economical operations. Even though the size of operations has increased, census data show that the aver- age cattle farm in the U. S. markets only 8,000 pounds of beef animals per year. This is 8 1,000-pound animals or 16 500- pound animals, the national average. The distribution is skewed in the beef industry as it is in all other agricultural industries. A large number of farms market a small proportion of the total output. Census data show that Iowa in 1954 marketed an average of only 21 head of cattle per farm. Seventy per cent of Iowa's farms reported selling 19 or fewer cattle. Eighty-seven per cent of the farms sold less than 40 beef animals. In Cali- fornia an average of 54 were sold, with nearly one-half the farms selling fewer than 10 head. Colorado reported average sales of 49 head in 1954, with one-half of the farms selling fewer than 10 head. These units seem small when compared with the cattle feedlot which fattens 75,- 000 head per year. You can readily see how difficult it is to introduce innovations and systems into an industry with so many small units. In my opinion, this huge industry with no great geographic concentration and with millions of managers means that new methods and ideas are adopted slowly. Over 10 million head of fed cattle are marketed annually in the United States (19). Fed beef makes up about 45 per cent of the total beef output. In the last 15 years, both the number of cattle on feed and the ratio of marketings to inven- tories have increased. In 1946, 4.2 mil- lion head of cattle were on feed January 1 and 6.2 million head were marketed during the year. In 1956, 6.0 million head were on feed January 1 and over 10.5 million were marketed. So, 10 years ago the ratio was about 1.50 and now it runs closer to 1.75. With more year- round feeding and hotter (higher energy) rations, this ratio is expected to increase. The corn belt still ranks first in cattle feeding but is losing, percentagewise, some cattle feeding to other areas. Twenty years ago over 80 per cent of all cattle on feed, when the January 1 in-

120 BEEF FOR TOMORROW ventory was taken, were in the corn belt. Today this is down to around 70 per cent. The western states have picked up these 10 percentage points. Added to the increase in January 1 inventory numbers is faster feeding done in the West. On the average, California feeds three batches of cattle in each feedlot each year, Colo- rado feeds over two and the corn belt not quite two per year. Traditionally, corn belt cattle feeders have fed relatively small lots of cattle and have worked cattle feeding into winter months to utilize labor when field opera- tions were light. Feeding in the western states is generally of a different type. Small feedlots in the West account for only a small percentage of all cattle fed. Scott (20) reported that in 1952-53 only 1 per cent of all cattle on feed in Cali- fornia were in feedlots of less than 100 head. For the West as a whole, only 10 per cent of all cattle on feed were in lots of under 100 head. Of the 496,000 head of cattle in California feed yards on Janu- ary 1, 1957, 92.7 per cent were in lots whose capacity exceeded 1,000. Only 0.3 per cent were in small farm feedlots han- dling 100 head or less. The farmer-feeder is still dominant in the corn belt, but commercial feedlots are springing up. Specialization in cattle feeding has been made possible by push- button feed mills and automated feeding operations. Custom feedlots have started operating in the corn belt, the South and the Southwest, as well as in the West. These definitions are used in this paper: Farmer-feeders—farmers who earn the major share of their income from non- cattle feeding enterprises. Cattle feeding often is an operation which utilizes labor in the months when field work is at a minimum. Commercial feeders—cattle feeders who earn the major share of their income from feeding their own cattle. They generally have cattle on feed each month of the year. They may or may not also grow rrops. Custom feeders—cattle feeders who have facilities and do the feeding of cattle which other people own. They may also feed their own cattle, but a large share of their income comes from the receipts from feeding cattle belonging to others. Often they do not grow crops. Trend in Size of Cattle Feed Yards Hopkin studied feed yards in Cali- fornia and showed that there are econo- mies of size (21). Knight and Bortfeld came to the same conclusion in Kansas (22). Table 1 shows the nonfeed costs and other cost factors of six groups of feed yards of different sizes. The econo- mies of size include both the economies of intensive use of plant and economies of scale. You will remember that Cali- fornia feeders feed up to three separate lots of cattle per year and corn belt feeders do not average two lots per year. In talking to the operators of over 30 cattle feed yards in Colorado, California and Arizona, the writer concluded that the size of the large yards would continue to increase because the operators said there were additional economies expected by adding more pens. Montfort, near Greeley, Colorado, planned to expand from 28,000 to 30,000 in 1959. Several small yards—farmer feed yards—were ob- served to be empty. Local people said that the smaller operators were having problems obtaining feeder cattle and com- peting with the larger yards. Hopkin showed that the net nonfeed costs were 50 per cent higher for the smallest group of yards compared with the largest group. This is quite a difference and very diffi- cult to offset, even if home-produced feed and underemployed seasonal farm family labor are used in the feeding operation. The writer concluded from talking with owners and managers that there will continue to be an increase in the size of feed yards. Increased size permits a spe- cialization of functions within a feed yard. When the numbers of cattle are increased sufficiently, one man can spend full time mixing rations, another can

PRODUCING BEEF ECONOMICALLY 121 TABLE 1 A comparison of average daily nonfeed costs per head and other factors by size of yard Size group I II m IV V VI Range in feedlot capacity Below 1,200- 2,500- 5,000- 8,000- 14,000 1,200 2,499 4,999 7,999 13,999 & above Number of feed yards per group 17 14 13 12 11 10 Average capacity 486 1,498 3,205 6,479 10,531 18,053 Average number fed 784 2,300 4,947 10,984 20,160 35,568 Average investment per head fed in feed- $23.53 $24.93 $23.83 $18.85 $19.62 $17.44 yard facilities Average nonfeed costs per day (cents) (cents) (cents) (cents) (cents) (cents) Labor (other than office) 5.79 4.08 4.20 3.81 3.52 3.30 Depreciation and repair of equipment 1.37 1.45 1.39 1.10 1.14 1.01 Taxes .79 .83 .79 .63 .65 .58 Interest on investment 1.57 1.66 1.59 1.26 1.30 1.15 Insurance .36 .37 .36 .28 .29 .26 Fuel and power .56 .74 .57 .57 .45 .39 Vet and medicine .35 .38 .30 .31 .26 .31 Death loss 1.05 .87 1.16 .99 .83 .73 Administration and overhead .81 .80 .74 .35 .48 .84 Gross nonfeed costs 12.65 11.18 11.10 9.30 8.92 8.57 Credit for manure .88 .88 .88 .88 .88 .88 Net nonfeed costs per day 11.77 10.30 10.22 8.42 8.04 7.69 Source: John A. Hopkins, Economies of Size in the Cattle-Feeding Industry of California, Journal of Farm Economics, Vol. XL, No. 2, May 1958, Appendix Table 1. spend full time "riding the pens," a third can spend full time "doctoring cattle," and a fourth can spend full time market- ing cattle. Financing should also be con- sidered as a reason why size will increase. Operations of large commercial and cus- tom cattle feed yards undoubtedly have access to credit through institutions not generally open to smaller operators. This access will permit them to expand further if they operate as successful businessmen. I feel that normal agricultural credit in- stitutions have not yet adjusted their lending to average farm operators to per- mit these farmers or ranchers to increase to the size necessary to provide incomes comparable with incomes in other voca- tions. Vertical Integration in the Beef Industry Vertical integration is the control by a single firm of two or more stages in the chain of production, processing, and dis- tribution. This control may be partial or complete; as a minimum it involves some business relationship that is closer than an open market relationship. The chain extends from the supply of inputs or production resources (feed) to the point at which the commodity (beef) reaches the consumer. Vertical integration may come about by cooperative arrangements, by the use of contracts or by ownership. Using this definition, I researched the current status of integration in the beef industry in the United States in the spring of 1958. In my paper at the Institute of Animal Agriculture in April, 1958, I re- ported that from 10 to 20 per cent of the fed cattle slaughter was coming from inte- grated arrangements. In the meantime I have done more research and have con- cluded that the percentage continues in this range. The present trends in the cattle indus- try indicate that capital can be substituted for labor. One of the efficient cattle feed- ers in Colorado told me that one man could feed 3,500 to 4,000 cattle daily. Con- trast this to the 16 head marketed annu-

122 BEEF FOR TOMORROW ally from the average cattle farm in the U. S. We have recognized that antibiotics and synthetic hormones encourage more efficient feed utilization and more rapid gains. Top management is needed to capitalize on intensive operations and not make costly mistakes in using new feeding techniques. These points have encour- aged integrated operations. To learn why retail food companies, meat packing companies, and ranchers (the principal integrators) were interested in integrated beef cattle operations, the writer interviewed retail food company and meat packing executives, ranchers, secretaries of state cattle associations, na- tional association executives, USDA and college experts, feedlot owners, and man- agers and bank executives. The writer traveled 10,000 miles collecting informa- tion which is given here in condensed form1 (23). Meat packers shipping meat interstate report their operations to the Packers and Stockyards Administration (PSA). Retail food companies who operate meat packing plants also report on their meat packing operations to the PSA. The PSA Docket (24) reported the number of cattle fed by packers in 1954, 1955, 1956, and 1957 and showed that between 500,000 and 560,000 head of cattle were fed in each of these 4 years. This number amounts to around 5 per cent of all fed cattle mar- keted per year. When the packers not covered by the PSA Act and the ranchers who have cattle custom fed are included, the percentage more than doubles. There are other integrators besides the three principal groups mentioned, but the num- ber of cattle integrated by them is small. These facts lead the writer to conclude that between 10 and 20 per cent of the industry is integrated. A bulletin published in 1952 (25) re- ported that packers gave the following 1 The American National Cattlemen's Associa- tion sponsored this study as a part of the research done for its Fact-Finding Committee. Dr. H. DeGraff, Research Director of the Fact-Finding Committee, gave permission for material in the report to be used in this paper. reasons for feeding cattle: 1) the need for a more uniform supply of desired grades and weights, 2) to finish animals that are in feeder flesh when bought but which packers must buy in mixed lots, 3) to pro- vide animals for slaughter when weather conditions shut off receipts, 4) to carry out supplemental feeding tests, 5) to create more interest in cattle feeding in a particular area, and 6) to permit the plant labor force and other facilities to be used more efficiently. In the interviews with packing company executives in 1958 these reasons were re- iterated. One reason given by all com- panies was flexibility. Being able to capitalize on all opportunities is extremely important in the meat packing industry. Having a supply of cattle ready for slaughter at all times was reported to be a valuable asset to packers who slaughter cattle. WTorld War II was cited as an important reason why packers fed cattle. O.P.A., rationing and other rules, regulations, and restrictions which were in effect during the war encouraged many packers to enter the cattle feeding business so they could have cattle to slaughter and to reduce the cost of fat cattle. Being business firms interested in earn- ing profits, packers also reported there were times when they believed that their earnings could be improved by buying feeders and adding the finish themselves. In their opinion, market prices for feeder cattle relative to the expected future mar- ket prices for slaughter cattle sometimes seemed low and favored the purchase and feeding of the feeder cattle. The number of cattle fed by packers has not increased during the past five years. Packers are feeding fewer cattle in their own facilities because of the in- creased number of commercial and custom feed yards, lower profits on the average from feeding, and the availability of more fat cattle. Packers are having more cattle fed in custom yards because of the loca- tion of these yards, the larger number of custom feed yards, and because custom

PRODUCING BEEF ECONOMICALLY 123 yard operators will feed as the packer directs and finish and deliver the cattle when the packer wants them. Meat packers are expected to feed about the same percentage of the total number fed as they have in the past five years. This means an increase in actual numbers as fed cattle numbers rise to 11 then to 12 million head. Specification buying by re- tailers means that packers must have ac- cess to certain grades and weights of slaughter cattle so that they can fill their specialized orders. Food retailing companies who feed cat- tle generally own and operate packing plants or have a financial investment in packing plants. In many respects they have interests which are identical with strictly meat packing companies. The writer's interviews led to the con- clusion that the laws and policies in effect during World War II were the dominant reason for food chains entering the meat packing business and thence feeding cat- tle. One retail executive said, "My com- pany began operating packing plants dur- ing World War II. We did it to obtain meat supplies—supplies at prices in line with the retail price permitted under O.P.A." Other retail executives reported essentially the same thing. "Retail food stores must have meats," they said. Since beef makes up 10 to 12 per cent of total store sales, they indicated they had to have beef. The war period gave meat packing and cattle feeding experience to several execu- tives in many retail food companies. This experience convinced a few companies that they could continue to operate pack- ing plants to their advantage. On the other hand, other company executives re- ported they felt a larger return could be obtained on their dollars by getting out of the packing business. With beef supplies available at reasonable prices they got out of the packing business and began buying all meats from packers. In 1957 a report was prepared by the USDA (26) on the current activities and problems under the Packers and Stock- yards Act. This report states: "There are 14 chains presently filing reports as meat packers under the Act. This number in- cludes 6 of the leading chains . . ." The USDA was including: American Stores Co. First National Stores Co. Food Fair Stores, Inc. A & P Tea Co. The Kroger Co. Safeway Stores, Inc. Alpha Beta Packing Co. National Tea Co. Steen Bros. Food Stores T &: W Packing Co. Giant Food Shopping Center, Inc. Shaffer Packing Co. Southland Corp. Tom Boy, Inc. Of this number, American, Food Fair, Safeway, Alpha Beta, National, Steen Bros., and T &: W slaughtered. The other seven did not slaughter, but had process- ing or sausage plants. Since that time, Safeway sold its final slaughter plant and Shaffer was purchased by another chain and still does not slaughter. There has been a downward trend in the number of chain-owned meat packing plants since the end of World War II. Chains own and operate fewer packing plants because of low profits in meat pack- ing, larger supplies of beef and other meats and public pressures. Cattle feed- ing by food chains has declined because there are fewer chain-owned plants, cus- tom cattle feeding yards have increased in number, and the availability of cattle and beef has increased. With plentiful meat supplies and no controls I would expect a decrease in retail food chain cattle feed- ing and meat packing operations. Ranchers have increasingly held onto calves and feeder cattle and have had them fattened for slaughter in custom yards. The number of rancher-owned cat- tle which are custom fed will vary with the cattle cycle. Ranchers will sell feeder cattle and calves when they feel that feeder cattle prices are high relative to

124 BEEF FOR TOMORROW expected slaughter cattle prices. They will also sell when their supply of capital is low and they can't defer receipts from cattle. They will hold feeder cattle and calves and have them fed out when they think that they are low relative to ex- pected slaughter cattle prices and if they have enough capital to defer receipts from cattle. Ranchers are interested in flexi- bility, as are others. They are also in- terested in maintaining and increasing in- come. Feed supplies and relative as well as expected prices are important in what ranchers decide to do with their feeder cattle and calves. The availability of cus- tom yards and the services they provide will probably encourage more ranchers to have larger numbers of cattle fed out. The larger, better financed ranchers will probably hold title to the majority of rancher-owned cattle which are custom fed. Increases in numbers of cattle fed out for ranchers will more than offset the de- cline in numbers fed out for retailers. With packer-fed cattle numbers increasing slightly, the trend is for slightly more ver- tical integration in the beef cattle indus- try. Packer and chain feeding of cattle has contributed to the spreading out of fat cattle marketings through the year. It has helped reduce seasonal swings in cattle prices. Level marketings permit meat packers to use facilities more efficiently. Packer and chain feeding has also created an interest in cattle feeding in certain areas. As local feeding increases, packer and chain feeding often declines. The effect of packer and retailer feeding has been one of influence. The grade, weight, and sex desired by the retail trade have been influenced by packer and retailer feeding. Summary Review of the literature dealing with my topic leads me to conclude that the production efficiency in beef cattle is in- creasing. Compared with other food com- modities, the beef story could be brighter. The multiplicity of possible management systems and the resulting heterogeneous beef products which are possible makes the interpretation and synthesis of re- search results for the industry a most diffi- cult task. Some of the advances and the factors which have influenced the cattle industry are: 1) less seasonality in cattle production and marketing, 2) faster growing and fat- tening of cattle, 3) increased performance testing and use of tested breeding stock, 4) better disease and insect control and less death losses, 5) improved management of the herds with increased calving per- centage, 6) larger units in both production and fattening, 7) increased use of custom and commercial feeding operations, 8) growing and harvesting of higher quality roughages and feeds, 9) substitution of capital for labor in roughage and feed handling operations, 10) increased use of credit and an increase in vertical integra- tion, 11) decrease in vertical integration on the part of food chain companies, 12) increase in vertical integration on the part of ranchers, 13) use of a wider range of rations—high roughage rations used in some cases and very high energy rations used in others and, 14) expanded use of feed additives, implants, minerals, and other chemicals and biologicals. The data do not permit a clear sum- mary of the contributions of research to the efficiency of feed conversion in cattle. There is no question about increased beef production per beef animal. The ques- tion is how much more efficient feed con- verters the 1960 models are compared with the 1930 models. Everyone in the beef industry will need to adopt cost reducing and output increas- ing innovations. Beef occupies a favored position among protein foods, but con- tinued progress must be made in the in- dustry if it is to maintain this position. Improved management systems and in- creased production efficiency will be needed to keep beef the king of meats. Comparisons reveal that the pace at which innovations are adopted in the beef in- dustry will need to be accelerated.

PRODUCING BEEF ECONOMICALLY 125 Can this industry afford the luxury of a laissez faire policy with regard to research? The industry is large and widely scattered. Much unnecessary and costly duplication can be expected from uncoordinated re- search done by over 50 Agricultural Ex- periment Stations, the USDA, busi- nesses, and breed associations. It would appear that a beef industry committee or a beef industry congress could serve a con- structive purpose in reviewing current re- search so as to point out the overlaps and the gaps in the total industry research programs. References 1. Bradford, L. A., and Johnson, G. L. 1953. Farm management analysis. John Wiley & Sons, Inc., New York. 2. Nelson, A. G. September 1954. Relation of feed consumed to food products produced by fattening cattle. Tech. Bui. 900. U.S.D.A. 3. Smith, V. E. August 1955. Perfect vs. dis- continuous input markets: a linear pro- gramming analysis. J. of Farm Econ. XXXVII 3. 4. Hoglund, C. R. Economic analysis of feed substitution data for beef production. Ditto. Agr. Econ. Dept., Michigan State Univ. 5. Stangeland, S. January 1952. Input and out- put relationships in livestock production. Mimeo. Agr. Econ. Pamph. 38. South Dakota Agr. Exp. Sta. and Bureau of Reclamation, U. S. Dept. of the Interior. 6. Neal, E. M., and Jones, J. H. Feed and grazing management in farm steer beef production. Mimeo. Texas Agr. Exp. Sta. Prog. Rept. 2047. Cattle Ser. 147. January 1948. A comparison of different systems of feeding beef cattle with special emphasis on utlization of hay and pasture. Mimeo. Indiana (Purdue) Agr. Exp. Sta. and Soil Cons. Serv., Region III, USDA Memo. No. 666-31. Cohee, M. H., R. E. Bennett, W. H. Peters. G. A. Pond, and A. R. Schmid. April 1949. A comparison of beef cattle feeding systems with special attention to the use of hay and pasture. Mimeo. Soil Cons. Sen'., Upper Mississippi Valley Region, USDA. HI-2805. June 1951. A study of three methods of utilizing pastures and grain in beef produc- tion on Marshall silt loam in southwestern Iowa. Mimeo. Iowa Agr. Exp. Sta. FSR- 38S. 7. Duitsman, W. W., and F. B. Kessler. April 27, 1956. Beef cattle feeding investigations 1955-56. Kansas (Hays) Agr. Exp. Sta. Cir. 334. Mueller, A. G. December 1958. Twentieth annual report of feeder cattle fed during the feeding year 1957-58 by cooperators in the Farm Bureau Farm Management Serv- ice. Illinois Agr. Exp. Sta. AE 3356. 8. Breimyer, H. F. July 1959. Our cattle herd is more productive. Agricultural Situation. 43 (7): 9. Byerly, T. C. December 1958. The biologi- cal sciences. J. of Farm Econ., XL (5) . 10. Ralston Purina Company 1958 annual report. Ralston Purina Co., St. Louis 2, Mo. 11. November 1958. Agricultural outlook charts 1959. AMS and ARS, USDA. 12. Ives, J. R. December 1957. An evaluation of available data for estimating market supplies and prices of cattle. J. of Farm Econ. XXXIX, (5). 13. Strohm, J., editor. 1959. 1959 farm man- agement digest; 50 money making ideas. Truck Marketing Dept. Ford Div. Ford Motor Co. 14. Knox, J. H. November 29, 1958. Perform- ance testing of beef cattle. Mimeo. Paper Presented at Extension Section, annual meeting of American Society of Animal Production, Chicago FES, USDA. 15. Marlowe, T. J., C. M. Kincaid, and G. W. Litton. May 1958. Virginia beef cattle; per- formance testing program. Virginia Agr. Exp. Sta. Bui. 489. Fellhauer, T. May 1958. High performance plus quality essential to profitable beef production. Wyoming Agr. Ext. Serv. Cir. 155. 16. The Performance Register. June 1959. Per- formance Registry International, Box F, Foraker, Oklahoma. 17. Ellis, G. F., of Bell Ranch, New Mexico. Let- ter dated July 2, 1959. 18. Nellor, J. E., and H. H. Cole. August 1956. The hormonal control of estrus and ovula- tion in the beef heifer. J. of Animal Sci. 15 (3). 19. June 1959. Supplement for 1958 to livestock and meat statistics. AMS, USDA Stat. Bui. 230.

126 BEEF FOR TOMORROW April 1959. Commercial livestock slaughter; number and live weight, by states; meat and lard production, United States; by months 1958. Mt. An. 1-2-1 (59). Crop Reporting Bd., AMS, USDA. September 1958. Animal units of livestock fed annually, 1909 to 1957. ARS, USDA Stat. Bui. 235. 20. Scott, F. S., Jr. December 1955. Marketing aspects of western cattle feeding operations. Nevada Agr. Exp. Sta. Bui. 190. 21. Hopkin, J. A. May 1958. Economies of size in the cattle-feeding industry of California. J. of Farm Econ., XL (2). 22. Knight, D. A., and C. F. Bortfeld. September 1958. Labor and power requirements by size of enterprise for beef cattle systems in eastern Kansas. Kansas Agr. Exp. Sta. Tech. Bui. 98. 23. Kramer, R. C. July 1959. Cattle feeding by or for packers and retailers. Mimeo. Re- port to the Research Director of the Fact- Finding Committee of the American Na- tional Cattlemen's Ass'n. 24. September 1958. Packers and stockyards docket. USDA. 25. Brensike, V. J. May 1952. Marketing feeder cattle and sheep in the North Central Region. Nebraska Agr. Exp. Sta. Bui. 410. 26. April 4, 1957. Report on current activities and problems under the packers and Stock- yards Act. USDA Mimeo. 1101-57. Other Literature Studied But Not Cited Stockmen's handbook. December 1955, 1956, and 1957 editions. Institute of Agricultural Sci- iences, State. Coll. of Washington. Hecht, R. W. May 1955. Labor used for live- stock. ARS, USDA Stat. Bui. 161. Farm Profit, 1959 Annual (Massey-Ferguson) , 749 N. 2nd St., Milwaukee 3, Wise. Peacock, F. M., and W. G. Kirk. July 1958. Feed lot performance and carcass grades of Brah- man and Brahman-shorthorn steers. Florida Agr. Exp. Sta. Bui. 597. Woodward, R. R., J. R. Quesenberry, and F. S. Willson. December 1954. Production and car- cass quality in beef cattle. Montana Agr. Exp. Sta. Cir. 207. August 1956. Farm output; past changes and projected needs. Agr. Inf. Bui. 162, ARS, USDA. Malone, C. C. November 1947. Guides to profit for cattle feeders. Iowa Agr. Ext. Serv. Pamph. 127. Hoffman, E. N., and J. E. Oldfield. September 1958. Supplementing potato diets for fattening cattle. Oregon Agr. Exp. Sta. Cir. of Inf. 595. Warner, J. H. December 1958. Commercial cattle feeding in Ohio. Ohio Agr. Ext. Serv Bui. 355. Jennings, R. D. November 1958. Consumption of feed by livestock, 1909-56; relation between feed, livestock, and food at the national level. USDA Production Res. Rept. 21.

Discussion Session III How to Produce Beef Economically ROBERT C. JONES: Dr. Kramer, you indicate substantial savings on large commercial feed business, and yet you ex- pect only slight increase in integration. Would you please reconcile this? DR. KRAMER: The Montford feed lot in Colorado has been used as an example in many cases. Supposedly, most of the cattle fed there are owned by Mr. Montford and his son Kenneth. What I am thinking, using this as an example, is that the commercial feeder will be the private entrepreneur who buys and puts gains on the cattle and then, after they are ready for slaughter, will make them available for packers. I know and you know where a lot of cattle go from the Montford line, but I am thinking that much of the feeding will be done in the commercial feed lots where this is primar- ily income from the owner and the opera- tor of the lots. This owner and operator will buy from the cow-calf rancher the feeders and the calves that he puts in his pens, and after he has done the job of putting on finish, he will then make them available to the packers. Committee Recommendations Basic research is needed on the nutritional requirements of beef cattle under different environmental, especially climatic, conditions. Improved methods of controlling the reproductive cycle of range cattle are needed before artificial insemination can be effectively used for increasing efficiency of production in beef cattle commercial herds. Attempts should be made to increase and coordinate genetic re- search and to determine the extent which meat quality and economy of gain of animals can be improved through breedings. Reorganization and extension of performance testing on a uniform national scale for purebred and commercial beef herds is needed. Studies should be made to determine proper criteria for describing "ideal type" of breeding animals as they relate to desirable traits in carcasses of slaughter animals. Research is especially needed on the relationship of conformation to cutability and beef quality as a guide to breeders, feeders, and buyers of slaughter cattle. Basic research is urgently needed on the endocrine physiology of growing and fattening beef cattle on the role of feed and other addi- tives on beef production efficiency, and on beef quality and compo- sition. 127