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OCR for page 10
DIETS AND
FEEDING PRACTICES
PELLETE D VS . NO N P E LLE TE D FE E D S
Observation of rabbits indicates that they prefer a pel-
leted diet to one in a meal form. They will adjust to a meal
diet and accept it satisfactorily, but during the adjustment
period intake may be very low and feed spillage exces-
sive. Some individuals may refuse to consume a nonpel-
leted experimental diet. Unless fat or molasses is added to
the diet, dustiness may be a problem with meal-type
diets, furler contributing to their lack of palatability.
Chapin (1965) compared performance of growing rab-
bits on a commercial pelleted diet (0.48 x 0.63 cm) with
the same diet in the ground form. He also compared
performance on a commercial meal-form diet with He
same diet pelleted. In each case, growth rate and feed
efficiency were significantly better with the pelleted
diets. Lebas (1973) also observed improved growth per-
formance with pelleted diets, and King (1974) reported
. . A- .
slm1 ar zinc legs.
PARTICLE SIZE AND CRUDE FIBER
Physical form and particle size of feed ingredients may be
factors to be considered in rabbit diet formulation. Lebas
(unpublished observations) has found that the particle
size of alfalfa may influence the occurrence of enteritis.
Fine grinding (more than 25 percent passing a 0.2~mm
screen and 90 percent passing a 1.0-mm screen) tends to
promote diarrhea, whereas coarsely ground material does
not. The presence of undigestible fiber of large particle
size in the cecum and colon may be necessary for mainte-
nance of the epithelial tissue of these organs (Lebas,
1975b). Replacement of a poorly digested fiber source,
such as alfalfa, with a well-digested fiber source, such as
beet pulp, may provoke diarrhea (Lebas, unpublished
observations). These observations, as well as un-
documented statements of commercial rabbit producers,
suggest Hat the presence of undigestible fiber of large
particle size is necessary for normal functioning of the
rabbit digestive tract, and that the absence of this mate
rial, either through fine grinding or the use of digestible
sources of fiber (beet pulp), may result in changes in the
cellular structure of the digestive tract lining and
diarrhea. This aspect of feed preparation warrants consid-
erably more study.
PURIFIED AND EXPERIMENTAL DIETS
Studies involving strictly purified diets for rabbits are
few. In most cases, natural materials such as alfalfa or
green feed have been included. Gaman et al. (1970) re-
ported the composition of a purified diet that gave satis-
factory results; rabbits were fed this diet for periods up
to 2.5 yr during all stages of growth and reproduction. No
problems were encountered; performance was similar to
that of control animals fed a commercial diet. Composi-
tion of the diet is shown in Table 2. The vitamin mixture
used may contain an excess of some of the vitamins, and it
includes some vitamins (e.g., ascorbic acid) for which no
dietary need has been demonstrated.
If possible, purified diets should be pelleted to in-
crease their acceptability and to minimize waste. Diets
should be kept under refrigeration to avoid rancidity, or
an approved antioxidant maY be added. Use of highly
basic mineral mixtures should be avoided. Hove and
Herndon (1955) found that potassium acetate or potas
c, ,
slum carbonate in a mineral mixture led to rapid deterio-
ration of the diet. Cheeke (1972) observed that Torula
yeast has potent antioxidant activity and Hat inclusion of
2 percent Tonala yeast in a diet will stabilize it. The use of
lard or tallow in place of corn oil is also of assistance in
preventing rancidity.
Acceptability of feeds by rabbits is a problem in nutri-
tion research. Cheeke (1974) has examined feed prefer-
ences. While more extensive data are needed, this work
suggests some dietary modifications that may be helpful if
palatability is a problem. Adult Dutch male rabbits
showed a marked preference for a barley-based diet con-
taining sucrose over the same diet without sucrose, and
preferred the plant proteins, soybean meal and cotton-
seed meal, over meat meal and fish meal. A diet with 5
10
OCR for page 11
Nutrient Requirements of Rabbits 11
percent corn oil was strongly preferred over a similar diet
with no added corn oil' and a 10 percent level of corn oil
was preferred over a 20 percent level. Furler identif~ca-
tion of preferences or dislikes of rabbits would aid in
formulating acceptable diets.
DIET INGREDIENTS AND EXAMPLES OF
ADEQUATE RATIONS
Rabbits consume many kinds of feeds satisfactorily. The
feeds selected for use should be determined by relative
costs and regional availability.
The following simple classification of feeds will guide
the discussion of the merits of individual feed ingre-
dients.
· Green or succulent feeds. Typically average 70-90
percent of H2O. Growing pasture plants, root crops, cab-
bage, etc.
· Dry feeds. As fed will average only 10-15 percent of
H2O.
· Roughages. Those having high fiber content and rela-
tively low digestibility and therefore low in energy value.
Hay, etc.
· Concentrate feeds. Those having low fiber content
and relatively high digestibility and therefore high in
energy value.
· High carbohydrate concentrates. Those relatively
high in the more digestible carbohydrates but low in
protein content. The cereal grains (corn, wheat, oats, etc.)
and their milled by-products as wheat bran, middlings,
hominy feed, etc.
· Protein supplements. Those that are high in protein.
Soybean meal, peanut meal, dried milk by-products, etc.
The green feeds are widely fed to rabbits, especially by
small producers. They are generally succulent and highly
palatable. However, the cost per unit of nutrients is too
high for the commercial producer, and He high water
content renders them bulky and too low in energy for
efficient production of meat or for lactating females.
The dry roughages, primarily hay, normally make up
about 40-80 percent of the diet for rabbits. While rela-
tively low in energy value, the hays are economical
sources of many nutrients, notably protein, some vita-
mins, and some mineral elements and furnish necessary
amounts of fiber for a balanced diet. There are two prin-
cipal classes of hay: legume (alfalfa, clovers, etc.) and
grass (timothy, bluegrass, orchard grass, etc.~. As a group
the legume hays are superior to the grass hays in that they
are generally more palatable, are significantly higher in
protein and in calcium, and are preferred by the rabbit. In
most sections of the country, alfalfa is generally used.
The high carbohydrate concentrate feeds are primarily
rich sources of energy and, when added to the roughage,
increase the energy density of the mixture to the point
where it is adequate to meet the higher energy needs of
producing rabbits growth, meat production, and lacta
tion. These concentrates may be fed as whole grains,
ground and fed as a meal, or compressed into pellets.
Some whole grains such as flint corn are so hard Hat
grinding improves digestibility significantly.
Protein supplements are concentrate [Beds that are high
in protein, and they are used to increase the level of pro-
tein in the total diet to the recommended level. For the
most part, protein supplements of most interest to rabbit
growers are derived from plants rather than the more ex-
pensive animal protein supplements. The most widely
used is soybean meal, Tough, in usual feed combinations,
linseed meal, peanut meal, and sesame meal may also be
used successfully. If cottonseed meal is used, it should be
treated for removal of gossypol, and even then it should
be limited to no more than about 5-7 percent of the diet.
Miscellaneous feeds include a wide variety of ingre-
dients that are of little interest to commercial producers
but may be of interest to small operators. Table wastes,
except meat, fat, or spoiled foods, are acceptable. Milk
and milk by-products are excellent but usually are too
expensive. In some countries many weeds are used by
small producers, and a summary of these is given by
Aitken and Wilson (19621.
In practice, salt is generally added to a diet at a level of
0.5 percent or provided free choice as a salt block. The
example diets in Table 3 are adequate in mineral ele-
ments so far as is known.
Since He great majority of rabbit breeders, including
those raising rabbits in medical and biological lab-
oratories, use commercially prepared pelleted feeds,
the diets in Table 3 are formulated on the basis of suitabil-
ity for pelleting. It should be stressed that many over
feed combinations are possible.
Certain feeds are of interest because of their detrimen-
tal effects. There is evidence that cottonseed meal may
have a cumulative toxic effect (Holley, 19551. This, in
addition to the high sensitivity of rabbits to gossypol in
untreated cottonseed meal, would suggest caution in its
use until further research is done. It has been dem-
onstrated by several workers Hat the feeding of large
amounts of cabbage or rapeseed produces goiter in rab-
bits as well as in other species (Yamamoto, 1959;
F'edelli-Avanzi and Janella, 1976~. Other toxic feeds are
listed by Aitken and Wilson (1962~.
GERM-FREE DIETS
The nutrient requirements for germ-free rabbits have
been subjected to only a few studies, but the require-
ments, except for B vitamins, do not appear to be funda-
mentally different from those of conventional rabbits.
Some differences have been noted in the absorption of
iron and copper (Ready et al., 1965).
In the absence of intestinal flora, vitamins of the
complex must be present in the diet to supply those
otherwise synthesized by conventional animals. Nutri-
tionally adequate diets for germ-free rabbits have been
described by Reddy et al. (1968~.
OCR for page 12
12 Nutrient Requirements of Rabbits
ANTIMICROBIAL AGENTS
Antibiotics, sulfonamides, and nitrofurans added to the
feed or drinking water have been evaluated for their
effects upon growth or the control of coccidiosis and
enteritis. In general, the antibiotics have not shown con-
sistent beneficial ejects upon growth, but in some cases
1 hey have aided in the control of enteritis. Sulfonamides
are of value in the control of coccidiosis, and nitrofurans
have had limited effect upon enteritis. The research with
these agents and the practical aspects of their use have
been reviewed by Hagen (19741. The use of antibiotics
and other antimicrobial agents is controlled by federal
regulations, and readers should consult Me Food and
Drug Administration (FDA) regarding the latest rulings on
use of feed additives.
At present the following agents with amounts and indi-
cations for use are permitted in rabbit feeds. Oxytetracy-
clene at a level of 10 g per ton is permitted as an aid in
stimulating grown and improving feed efficiency. Sul-
faquinoxaline, 0.025 percent, continuously for 30 days,
0.025 percent intermittently for 2 days per week, or 0.1
percent for 2 weeks may be included as an aid in control-
ling coccidiosis due to Eimeria stiedae.
Lawrence and McGinnis (1952) reported no improve-
ment in grown of rabbits fed Terramycin in amounts up
to 50 mg per kg of diet. Chlortetracyclene (100 mg/kg of
diet) and oxytetracyclene (50 mg/kg) had no effect upon
grown except in the doe's first litter. The high levels of
antibiotic reduced the incidence of enteritis and mortality
due to enteritis but had no effect on the young once
enteritis had appeared (Casady et al., 1964a). Zinc
bacitracin (50 mg/kg of diet) likewise was found to have
no effect upon growth but reduced evidence of enteritis
(Casady et al., 1964b). No evidence of increased grown
was observed by Huang et al. (1954) with Terramycin,
Aureomycin, or Aureomycin plus vitamin B ill.
Studies in England have indicated beneficial effects of
oxytetracyclene, chlortetracyclene, and virginiamycin
upon growth, but no effect was noted with penicillin
(King, 1962, 1966, 1967, 1974a, 1974b). Flavomycin was
observed to decrease feed intake and improve feed eff~-
ciency but had no effect upon daily gain (Schlolaut and
Lange, 1973~.
Sulfamethazine (0.05 to 1.0 percent) in the feed, sul-
famerazine (0.02 percent) in the drinking water, and sul-
faquinoxaline (0.02 and 0.05 percent) in the drinking
water controlled liver coccidiosis. Intestinal coccidiosis
was successfully treated with 50 mg of sulfaguanidine per
100 g of diet daily for 2 weeks. Sulfamonomethoxine and
sulfadime~oxine (75 mg/kg of body weight) were also
effective. Limited studies with ni~ofurans have indicated
some effect upon growth and enteritis. Furazolidone (50
giton) increased weaning weight and reduced Me inci-
dence of enteritis. Nitrofurazone and furazolidone sepa-
rately and in combination did not prevent liver lesions
from coccidiosis, but the combination had some detri-
mental effect on the life cycle of coccidia (reports on
sulfonamides and nitrofurans cited by Hagen, 1974~.
OCR for page 13
TABLES
OCR for page 14
14 Nutrient Requirements of Rabbits
TABLE 1 Nutrient Reauirements of Rabbits Fed Ad Libitum (Percentage or Amount per kg of Diet)
. ~ ~ . ~ . . _ ~ ~ ~
Nutrients5 Grovv~hMaintenanceGestationLaceation
Energy and protein
Digestible energy (kcal) 2500210025002500
TDN (%) 65555870
Crude fiber (%) 1012b14D10-1201~126
Fat(%) 26262626
Crude protein (%) 16121517
Inorganic nutrients
Calcium (%) 0 4c0.4S.0.75b
Phosphorus (%) 0.22-'0.3700.5
Magnesium (mg) 300400300 400300 400300~00
Potassium (%) 0.60.60.60.6
Sodium (%) 0.20 ~0.26 ~0.26 ~0.2
Chlorine (%) 0.3D.d0.3D-a0.3 b.d0.3
Copper (mg) 3333
iodine (mg) o.2b0.25o.2bo.2b
Iron cccc
Manganese (mg) 8.5e2.5e2.5e2.5e
Zinc cc_cc
Vitamins
Vitamin A ('u) 580 >1160c
Vitamin A as carotene (mg) 0 g3b.e_l0 83b.e_
Vitamin D ~- gg~
Vitamin E (mg) 40h_c40h406
Vitamin K (mg) ii02
Niacin (mg) 180
Pyridoxine (mg) 39-j-j-
Choline (9) 1.2b-j-j-
Amino acids (%)
Lysine . 0.6599g
Methionine + cystine 0.6-O-9-g
Arginine 0.69g9
Histid~ne 0.3bD, gg
Leucine 1lb-9-99
Isoleucine 0 6bgDg
Phenylalanine + tyrosine 1.1 b-9-9-9
Threonine 0.6bggg
Tryptophan 0.26g- g-g
Valine Q76
Glycine
a Nutrients not listed indicate dietary need unknown or not demonstrated.
D May not be minimum but known to be adequate.
~ Quantitative requirement not determined, but dietary need demonstrated.
d May be met with 0.5 percent NaCI.
'Converted from amount per rabbit per day using an air-dry feed intake of 60 9 per day for a 1-kg rabbit.
~Quantitative requirement not determined.
° Probably required, amount unknown.
A Estimated.
' Intestinal synthesis probably adequate.
Dietary need unknown.
OCR for page 15
Nutrient Requirements of Rabbits 15
TABLE 2 Purified Diet for Rabbitsa
Ingredient
% of Diet
Isolated soy protein
Purified celluloseb
Corn oil
Mineral mixtures
Vitamin mixtures
Choline chloride (70%)
Antioxidant (Ethoxyquin)
Dr-Methionine
c'-Tocopherol acetate
Glucose monohydrate
Corn dextrin
Corn starch
Water (for pelleting)
20.0
16.0
5.0
6.6
0.2
0.1
0.025
0.2
50 ~u/kg
15.0
5.0
27.4
5.0
· Garnan and Fisher (1970).
DSolka Floe, Brown Co., New York, N.Y.
'Composition (in mglkg): CoCI2~6H2O, 3.5; CuSO4~5H20, 34.6; MnSO4.H2O,81.1;
ZnS04, 169; FeC6HsO4. 14H2O, 706.3; (NH4)6MO7o24-4H2o' 22.7; (in g/kg):
K2HPO4, 10; KHCO3, to; NaHCO3, 8; NaCI, 5; CaCO3, 12.5; CaHP04, 10.
° Composition (in molly): thiamine-HCI, 25; riboflavin, 16; Ca pantothenate, 20;
pyridoxine-HCI, 6; biotin, 0.6; folio acid, 4; menadione, 5; vitamin B,2, 0.02;
ascorbic acid, 250; niacin, 150; vitamin A, 10,000 IU; vitamin Do, 600 IU;
cr~tocopherol acetate, 10 IU.
TABLE 3 Examples of Adequate Diets
for Commercial Production
Kind of Animal Ingredients % of Total Diets
Growth, 0.5 to4 kg Alfalfa hay 50
Corn, grain 23.5
Barley, grain 11
Wheat bran 5
Soybean meal 10
Salt 0.5
Maintenance, does and Clover hay
bucks, avg. 4.5 kg Oats, grain
Salt
70
29.5
0.5
Pregnant does, Alfalfa hay 50
avg. 4.5 kg Oats, grain 45.5
Soybean meal 4
Salt 0.5
Lactating does, Alfalfa hay 40
avg.4.5 kg Wheat, grain 25
Sorghum, grain 22.5
Soybean meal 12
Salt 0.5
' Composition given on an as-fed basis.
Representative terms from entire chapter:
nutrient requirements