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SYLVAN H. WITTWER Altering Fat Content of Animal Products through Genetics, Nutrition, and Managements This is an era of anxiety about our food supply. Serious questions are being raised about the future of animal agriculture, especially the future of beef production. It is generally conceded that grain in rations for finishing beef cattle will have to be reduced to compensate for current low prices received and the soaring prices for feed. This should be applauded by both consumers and producers. In addition to economic considerations, diversion of energy and pro- tein foodstuffs through animals may have to be curtailed in order to ensure a sufficient supply for human consumption. U.S. feed grain supplies are the lowest since 1957-1958. Then, however, U.S. in- ventories of livestock were much smaller and foreign demand for feed grain much less. Simultaneously, because of shortages and ever-higher prices, nations are now attempting to shore up their dwindling food and feed supplies. Concern about research investment should be directed to feedstufis for livestock that cannot be useful directly to man. These could include more effective utilization of annual and perennial forage crops, many plant residues, and numerous cellulosic materials. There is also the use of nonprotein nitrogen sources (ammonia solutions, urea) added to the whole chopped corn plant at the proper stage of maturity. This provides a ration of energy and protein that is completely adequate for finishing beef cattle and all dairy cows except * Michigan Agricultural Experiment Station Journal Article No. 7084. 80

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Altering Fat Content of Animal Products 81 the very high producers (Huber, 1974). Only 10~o-15% of the nation's corn crop is currently harvested as silage. Vast energy resources of the nation's number one crop are dissipated annually. Under some condi- tions, animals as well as grain can represent storage mechanisms for food. At issue is the survival of an industry. With cattlemen now struggling to overcome a severe price-cost squeeze, the question is: Who is going to survive? Live cattle wholesale beef prices plunged to a 2-year low on December 3, 1974. Corn that sells for $3.50 per bushel cannot be fed, with a profit, to steers that sell for $37 per 100 lb. There is the immediate challenge of reducing livestock numbers that have become dependent on the use of large quantities of feed grains. An important consideration is energy. Animal fat is energy. It is one of the most concentrated of natural resources. But animal fat is very costly to produce. We can no longer waste it; the economics are prohibitive. Overfat cattle are quickly becoming a luxury we cannot afford. Conversion ratios of feed energy to food energy are 5:1 for hogs, 8: 1 for broilers, and 18: 1 for beef. It has been estimated that the difference between Good and Choice beef is over 1,000 lb of feed (reveille, 19741. With an estimated 27 million head of feeders, this amount is in excess of 10% of our nation's corn crop. Translated into dollars at the present price of corn ($3.50 per bushel), the figu-. approaches $2 billion. Aside from economics, how- ever, there may still be issues of flavor, appearance, and acceptability. Again the question can be posed. With the domestic and global de- mands for grain, can we continue to feed beef and dairy cattle and produce chickens and pigs? The answer is yes, but we will have to feed them differently. The rumen of ruminants is essentially a fermentation vat. High-grain rations are no longer necessary in beef and dairy production. The carrying capacities of the western ranges and prairies could be doubled by improvement of native grasses and legumes, the introduction of new ones, and better water management. Such improve- ments would not require a major energy input. An opposing view is expressed by Mayer (19731. He emphatically states that the most important step we can take to ensure an adequate food supply for ourselves and the world is to reduce our consumption of meat. Mayer further states that the protein intake of adult Americans is at least twice as high as it needs to be. This has been confirmed by Hansen (1973) in nutrient density studies based on chemical composi- tion data of our total food supply. Further evidence has been provided by Leveille (1974) on the basis of the 1974 recommended dietary allowances (NRC, 1974b).

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82 SYLVAN H. WITTWER There is also a spate of reports on the importance of vegetable fiber in the diet and on health problems associated with an increase in uptake of animal protein, animal fat, and sugar (Burkitt et al., 1972; Eastwood, 1974; Eastwood and Mitchell, 1974; Leveille, 1974; Walker, 19741. It is good that energy inputs associated with economic and health- related aspects of animal foods, along with beef grades as determined by carcass fat, are coming under surveillance in alternative livestock- production operations. There are possibilities of reducing energy (feed) requirements and at the same time improving beef quality and nutritive value. Forages still furnish 75~o of the feed units for beef cattle, 65% for dairy cows, and 90% for sheep (Hodgson, 19741. Much of the grain particularly corn, sorghum, and barley fed to livestock is not acceptable as human food. There is a linkage between food, feed, and energy. Expressed as calories, they are the same. Ultimate prices of food and feed are in- separable from those of oil. The lag time will be short. A 400% in- crease in the price of oil has been accompanied by an almost threefold rise in the price of fertilizer and in turn by a rise in the price of corn, wheat, and soybeans. They are our three most important agricultural export commodities and the feed base for the livestock industry. There is the issue of conventional versus nonconventional foods. The concern is food for man and feed for animals. Currently 12 crops provide 80% of the food energy for man. Livestock is directly competi- tive with man for some of them. Nonconventional foods or feedstuffs, such as single-cell protein, leaf protein, microbial protein, fish-protein concentrates, and sterilized, dehydrated excrete of poultry, should first be evaluated as livestock or poultry feed supplements. Considerations for human food can come later. Marked changes in dietary habits do not come easily or quickly. A report by the Committee on Animal Nutrition (NRC, 1974a) high- lights a recommendation that increased effort is needed on the effects of nutrition on animal product composition. Reference is made to the relationship of dietary fat and saturated fat and in particular to cardio- vascular disease. Possibilities of using foodstuffs high in unsaturated fatty acids to qualitatively modify animal fats are summarized by Hoover (1973a,b). Major changes in composition of fats of ruminants can be induced by feeding "protected" polyunsaturated oils. The fatty acid composition of monogastric animals can also be controlled by diet food, as can the cholesterol content of eggs. New exotic livestock species and genetic combinations offer promise. Wild ungulates of East Africa and the domestic types differ significantly

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Altering Fat Content of Animal Products 83 in deposition of fat and in the resultant fat content. The carcass fat content of domestic cattle may range from 7% to over 30%, depending on nutrition and management. For wild animals in a semiarid tropical climate, there is little fat (0% to 6% carcass fat). Wild animals in North America, however, do deposit fat on a seasonal basis (McCulloch and Talbot, 1965; Talbot, 19661. American agriculture has enjoyed unlimited production resources since the days of colonization. But the era of cheap, abundant energy has come to an abrupt end. We are approaching the time when there will be a market demand for virtually all the fossil fuel that can be produced with existing technology and our current resource base. But the resource base can change with time and technology. I agree with Boulding (1974) that what we need now is an all-out program to capture solar energy, which is renewable, unlimited, and nonpolluting. A major research investment in improved efficiency of bio- conversion by the green plant through photosynthetic carbon dioxide fixation would provide ample food, feed, and fiber for a growing popula- tion; meet demands of an ever-increasing affluent society; and perma- nently undergird a flourishing and expanding livestock industry. REFERENCES Boulding, K. 1974. The world as an economic region. Pages 27-34 in Regional Economic Policy. Proceedings of a Conference. Federal Reserve Bank of Min- neapolis. Burkitt, D. P., H. R. P. Walker, and N. S. Painter. 1972. Effect of dietary fibre on stools and transit-times and its role in the causation of diseases. Lancet 2: 1408-1412. Eastwood, M. A. 1974. Dietary fibre in human nutrition. J. Sci. Food Agric. 25 (in press). Eastwood, M. A., and W. D. Mitchell. 1974. The place of vegetable fiber in the diet. Br. J. Hosp. Med. (January), pp. 123-126. Hansen, R. G. 1973. An index of food quality. Nutr. Rev. 31(1):1-7. Hodgson, H. J. 1974. We won't need to eliminate beef cattle. Crops Soils 27(2): 9-11. Hoover, S. R. 1973a. Research into foods from animal sources. I. Controlling level and type of fat. Prev. Med. 2:346-360. Hoover, S. R. 1973b. Research into foods from animal sources. II. Developments in beef and diary products. Prev. Med. 2:361-365. Huber, J. T. 1974. Protein and nonprotein utilization in practical dairy rations. Invitational paper presented at the Livestock Sections Dairy Cattle- Protein Physiology and its Application in the Lactating Cow Symposium, 66th Annual Meeting of the American Society of Animal Science, University of Maryland, College Park, July 28-31, 1974. Leveille, G. A. 1974. Issues in human nutrition and their probable impact on foods of animal origin. J. Anim. Sci. (in press).

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84 SYLVAN H. WITTWER Mayer, J. 1973. What we plant we reap. Fam. Health 5(11 ) :6, 54. McCulloch, J. S. G., and L. M. Talbot. 1965. Comparisons of weight estimation methods for wild animals and domestic livestock. J. Appl. Ecol. 2:59-69. NRC (National Research Council), Committee on Animal Nutrition. 1974a. Re- search Needs in Animal Nutrition. National Academy of Sciences, Washington, D.C. 38pp. NRC (National Research Council), Food and Nutrition Board. 1974b. Recom- mended Dietary Allowances. National Academy of Sciences, Washington, D.C. 128 pp. Talbot, L. M. 1966. Wild Animals as a Source of Food. Special Scientific Report. Wildlife No. 98. Bureau of Sport Fisheries and Wildlife, U.S. Department of the Interior, Washington, D.C. Walker, R. P. 1974. Dietary fibre and the pattern of diseases (editorial). Ann. Intern. Med. 80 ( 5 ): 663-664.