Animal Science \ 1Florida Agricultural
imeograph Report No. AN6'4-8 experiment Station
i ro- k iGanesville, Florida
COMPARATIVE FEEDING LIE O. CITRUS PULP
AND GROUND CORN AND COB I)LRATTENING STEERS/
C. B. Ammerman, P. A. van Walleghem, A. Z. Palmer
J. V. Carpenter, J. F. Hentges and L. R. Arrington/
Dried citrus pulp has been used principally as a feed for dairy
cattle (Arnold et al., 1941; Becker and Arnold, 1951; and Keener et al.,
1957) but it has also been found useful as a source of nutrients for
fattening beef cattle (Kirk and Davis, 1954; and Peacock and Kirk, 1959).
In the present study, the value of dried citrus pulp as a replacement for
a ground corn and cob meal mixture (80%j corn meal, 200 cob meal) for
fattening steers in dry lot was investigated. The effects of the differ-
ent rations on rate of gain, efficiency of feed utilization, dressing
percent, carcass grade and steak tenderness were determined. The effect
of changing the ratio of dried citrus pulp to corn and cob meal in the
ration on ruminal epithelium was also observed.
Twenty Hereford and four Angus yearling steers were used in this
experiment. The steers were implanted with two, 12 mg. pellets of
diethylstilbesterol two weeks before experimental feeding was started.
The average daily consumption per steer of a ration containing 42%
ground snapped corn, 42% dried citrus pulp, 14% cottonseed meal, 1%
trace mineralized salt and 1% defluorinated phosphate was increased to
seven pounds during the two week pre-trial period. Bermudagrass hay
was fed ad libitum during this period.
The steers averaged 674 pounds initially and were divided into four
groups of 6 steers each on the basis of breed and body weight. The
groups were randomly assigned to the four concentrate mixtures shown in
Table 1. The dried citrus pulp used was of good quality with very little
charred material present. The corn and cob meal mixture was made by
blending 20% ground corn cobs with 80% corn meal. Dried citrus pulp was
substituted for the corn-cob meal in amounts which provided ratios of
/ This study was supported in part by funds from the Citrus Processors
Association, Winter Haven, Florida and acknowledgement is made to the
American Cyanamid Co., Princeton, New Jersey for supplying Aurofac-1O
and to Commercial Solvents Corp., New York, New York for supplying the
vitamin A and D supplements.
/ Ammerman, Assistant Animal Nutritionist; van Walleghem, Research
Assistant; Palmer, Associate Meat Scientist; Carpenter, Assistant Meat
Scientist; Hentges, Associate Animal Nutritionist; Arrington, Associ-
ate Animal Nutritionist. The assistance of P. A. Hicks, J. F. Jeter,
Dr. F. C. Neal, R. A. Newman and Mrs. Barbara Sullivan is gratefully
0:66.6, 22.2:44.4, 44.4:22.2 and 66.6:0 for the four concentrates,
respectively. Nutrient composition of the concentrate mixtures and the
Bermudagrass hay is shown in Table 2.
Table 1. Composition of Concentrate Mixtures
< .. ... ... .,, ,
Dried citrus pulp
Corn and cob meaU&/
Cottonseed meal (41a protein)
Alfalfa meal (17% protein)
Salt (trace mineralized).j.
Vitamins A and D5/
A B C D
22.2 44.4 66.6
66.6 44.4 22.2 -
16.7 .6.7 16.7 16.7
11.2 11.2 11.2 11.2
3.3 3.3 3.3 3.3
1.1 1.1 1.1 1.1
0.55 0.55 0.55 0.55
0.55 0.55 0.55 0.55
+ + + +0.
100.00 100.00 100.00 100.00
21 Mixture of 80% corn meal and 200 ground corn cobs.
2/ Smith-Douglass Company, Norfolk, Va.
3/ Carey Salt Company, HuLchinson, Kan., listed minimum analysis
in percent: Fe, 0.27; Mn, 0.25; Cu, 0.033; Co, 0.01; Zn,
0.005; I, 0.007; and NaCI, 95.9.
n/ Initially, 0.55 pounda of Aurofac-lO or 55 ags aureomycin per
pound of concentrate. At 30 days, reduced to 11 mgs and at 45
days, reduced to 5.5 mgs aureomycin per pound of concentrate.
5/ 1100 I.U. Vitamin A palmitate and 200 I.U. Vitamin D2 added
per pound of concentrate.
Table 2. Nutrient Composition and Density of
Concentrate Mixtures and Hay_/
Density, Ib./cu. ft.
38.00 36.17 33.33 30.67
i/ All composition values expressed in percent on a 90% dry matter
Initially the steers were fed eight pounds of the concentrate mix-
ture per head daily and this amount was increased one pound per steer
daily until feed was refused. The concentrate was fed twice daily in
equal feedings and during the first 2 weeks, long Bermudagrass hay was
fed ad libitum. The hay was then reduced to approximately four pounds
per st'ee.daily and at the end of five weeks on test the hay for all
steers was reduced to about 1.5 pounds per head daily for the remainder
of the 105-day feeding trial.
Individual steer weights were taken on two successive days at the
beginning and end of the experiment and single weights were taken at
two-week intervals during the progress of the experiment. All weights
were taken at approximately 1:00 p.m. with the steers having had access
to feed and water. The final weights were shrunk 30 in calculating
total gains, average daily gains and dressing percent. At the time of
slaughter the rumen of each steer was emptied and a visual examination
of the epithelial lining was made. Carcass grades and marbling scores
were determined by a Federal beef grader and fat thickness over the rib
eye and the rib eye area were measured at the 12th rib. Steak tender-
ness was determined on 2, one-inch thick short loin steaks which were
broiled to an internal temperature of 165 F. A four-member panel
evaluated each steak and 3, one-half inch cores from each steak were
each sheared twice by the Warner-Bratzler Shear technique.
Calcium, phosphorus and proximate analyses of feed samples were
made according to the methods of A.O.A.C. (1960). The data were ana-
lyzed statistically by analysis of variance as described by Snedecor
(1956) and significant mean differences were determined by the multiple
range test of Duncan (1955)*
Results and Discussion
We.iht gains and feed consumption The effect of concentrate com-
position on average daily gain, feed consumption and feed required per
pound of gain is shown in Table 3. The data are presented for the
entire 105-day period and also for the last 91 days which eliminates
the first two weeks in which Bermudagrass hay accounted for approxi-
mately 38% of the total feed intake. The average daily gains in pounds
for the entire period were 2.92, 2.98, 3.26 and 2.90 for the concen-
trates containing 0, 22, 44 and 66% dried citrus pulp, respectively.
Although the gains were numerically greater when 44% dried citrus pulp
was fed there was no suggestion of a statistically significant differ-
ence in rate of gain. Average daily feed consumption was greater in
the lots gaining at the higher rates. This difference in consumption
of concentrate is observed more clearly when the data are presented
without the first 2 weeks included.
The feed consumption data suggest that the two rations containing
both dried citrus pulp and corn and cob meal were the most palatable.
The concentrate mixture highest in dried citrus pulp, was consumed in
the least amount and was likewise the most bulky mixture. It is noted
in Table 3 that the steers receiving this bulky concentrate mixture con-
sumed slightly less hay. The hay was fed at the rate of 1.5 pounds per
steer daily except for short periods when hay was refused in this lot.
The amount of long hay fed (5.9 to 6.65 of the total feed intake for the
four lots during the last 91 days) appeared adequate to prevent craving
of roughage by the steers. There was no evidence of chewing fences or
feed buLks in any of the lots.
Table 3. Effect of Dried Citrus Pulp and
Corn and Cob Meal on Average Weight Gains,
Feed Consumption and Feed Required Per Pound Gain
Citrus pulp Corn and cob meal ratio
0:66 224 44: 22 66:0
Total period, 105 days
Initial weigh- Ib 667 685 672 670
Final weight, Ib.I/ 974 998 1014 975
Total gain, lb. 307 313 342 305
Daily gain, Ib. 2.92 2.98/ 3.26 2.90
Daily feed consumption,lb.
Concentrate 22.05 24.78 23.91 20.92
Bermudagrass hay 2.27 2.27 2.25 2.11
Total 24.32 27.05 2".li6 23.03
Feed/cwt. gain, lb. 833 908 802 794
Last 91 day12/
Daily gain, lb. 2.76 2.92 2.94 2.62
Daily feed consumption,lb.
Concentrate 23.21 26.36 25.36 21.91
Bermudagrass hay 1.65 1.66 1.64 1.47
Total 24?T6 28.02 27.00 23.3
Feed/cwt. gain, Ib. 901 960 918 892
1/ Full weight off experiment shrunk 3 percent.
/ Since approximately 38% of the total feed intake during the first
2 weeks was hay, the data have been summarized excluding this
3/ Omitting the data for one steer which had foot rot during the
latter part of the trial, this average becomes 3.10.
Carcass characteristics Carcass characteristics as affected by
concentrate composition are shown in Table 4. Those steers receiving
the two rations intermediate in citrus pulp and which had gained
slightly more, tended to have a higher dressing percent and a higher
carcass grade than the steers in the other lots. Quality grades,
Table 4. Effect of Concentrate Composition on Carcass Characteristics
Carcass Citrus pulp:Corn and cob meal ratio Statistical
Characteristic 0:66 22:44 44:22 66:0 Significancel/
No. of steers 6 6 6 6 -
Dressing percent2/ 60.9ab 61. 5b 62.5a 59.4b *
Federal carcass grade3/ 14.7 15.7 15.7 15.1 N.S.
Individual quality grades/ 2 low choice 2 av. choice 2 av. choice 4 low choice
2 high good 3 low choice 4 low choice 1 high good
2 av. good 1 high good 1 low good
Marbling5/ 9.3 12.0 12.3 10.7 N.S.
Estimated % yield 50.4 49.1 49.8 50.3 N.S.
Chilled carcass wt., lb. 592.7 613.8 633.7 578.6 --
Fat over rib eye, in. 0.37a 0.52ab 0.57b 0.37a *
Est. % kidney knob 3.0 3.2 2.9 2.9 N.S.
Rib eye area, sq. in. 11.0 10.8 12.1 10.6 N.S. n
Panel/ 5.9a 6.4 6.4b 6.b aab
Warner-3ratzler Shear, IbS 9.6a 9.2ab 8.3b 8.4b *
S* Significant at the 5 percent level. Means in the same line with different superscripts are signifi-
cantly different at the 5 percent level according to Duncan's Multiple Range Test.
2 Based on full weights off experiment shrunk 3 percent and the 48 hr. chilled carcass weight.
Based on conformation, finish and quality. Low, average and high good grades represented by 13, 14, and
!/ Based on degree of marbling, maturity, color, texture and firmness of lean.
5/ Small minus, average s:~mall and small plus degrees of marbling represented by 10, 11, and 12, respectively.
6/ Estimated percent boneless, closely trimmed lean fr.m rou:;., rump, loin, rib and chuck.
7/ Ratings were from 1 to 9 with average, above average and very tender represented by 5, 6, and 7, respec-
/ Higher values indicate less tender; lower values more tender meat.
considering carcass maturity, marbling, and color and texture of the
lean, were determined in order to examine more closely the ration
effects. All carcasses in the lot receiving the concentrate containing
44% citrus pulp were low choice, or higher, while in the all corn and
cob meal-lot, only one-third of the carcasses graded as high as low
choice. Most of this difference can be attributed to degree of marbling;
carcasses from cattle fed the ration containing no citrus pulp lacked the
marbling of cattle receiving the other rations even though marbling dif-
ferences were not statistically significant. The estimated percent yield
was not significantly different between treatments. Significant differ-
ences in steak tenderness (P< 0.05) were obtained by the panel and by the
Warner-Bratzler Shear technique. Those steaks from the steers receiving
the higher levels of dried citrus pulp were the most tender.
The results obtained in the present study may be compared with
those reported by Peacock and Kirk (1959). Their data shed no signifi-
cant difference in daily gain, slaughter grade, or dressing percent be-
tween steers in dry lot when fed a concentrate mixture containing either
70% dried citrus pulp or ground snapped corn adequately supplemented with
protein and other essential nutrients.
Ruminal epithelium Observations made on the ruminal epithelium are
shown in Table 5. The color of the papillae varied from flesh to black;
the darker colors occurring with the rations higher in corn and cob meal.
In contrast to this, an earlier report by Ammerman et al., 1963 stated
that lambs fed rations containing 66% dried citrus pulp had ruminal
epitheliums which were brown to dark brown in color while lambs receiving
ground snapped corn had ruminal epitheliums of a normal flesh color.
In the present study eleven out of the 12 steers receiving the two
higher levels of dried citrus pulp had rumen papillae which were coated
with a gummy, brown to black covering. The coating appeared as a cap
over the free extremity extending over approximately one-fourth the
length of the papillae. A coating of similar appearance found in other
studies in which high levels of dried citrus pulp were fed, was identi-
fied histologically as necrotic epithelium admixed with bacteria and
material of plant origin.._/ The significance of this observation is not
understood at present and warrants further study. It was considered
that such a condition might affect the gain response of the animal but
such an observation cannot be clearly made on the basis of the data
shown in Table 5. Some clumping of the rumen papillae was observed but
this did not appear to be related to treatment.
Mineral consumption To obtain information on consumption of
mineral when offered free choice to steers consuming a ration supposedly
adequate in minerals, a mixture of 50% plain mixing salt and 501 feed
grade dicalcium phosphate (22% Ca, 18.5% P) was provided free choice to
the steers during the last two weeks of the feeding period. Consumption
of the mixture in gms. per steer daily was 37.8, 25.2, 18.9 and 00.0 for
the steers receiving 0, 22, 44 and 66% dried citrus pulp, respectively.
/ Information supplied by Dr. C. F. Simpson, Department of Veterinary
Science, Florida Agricultural Experiment Station.
The lower mineral intake, as level of citrus pulp increased, was per-
haps related to the higher level of calcium in citrus pulp (1.41%)
compared to corn (0.020).
Table 5. Average Daily Gains and Rumen Papillae
Characteristics of Individual Steers
Citrus pulp: Average Daily Rumen papillae characteristics
Corn .nd cob meal ratio Gain, Ib. Color Shapel Coatin-. Cluming
3.27 Dark gray Normal 0 0
3.16 Gray Long 0 Slight
0:22 2.89 Gray Normal 0 Slight
2.83 Light gray Normal 0 0
2oT7 Black Long 0 0
2.O0 Flesh Normal 0 0
3.47 Flesh Normal 10% 0
3.36 Flesh Normal 0 0
22:44 3.22 Dark gray Long 0 Severe
2.96 Light gray Normal O Slight
2.50 Flesh Normal 0 0
2.39 Flesh Normal 0 0
3.71 Flesh Normal 0 0
3.50 Flesh Normal 90% 0
44:22 3.32 Flesh Normal 90% Severe
3.30 Flesh Normal 60% 0
3.10 Flesh Small 30% 0
2.58 Flesh Small 90% 0
4.11 Flesh Normal 10% 0
3.53 Flesh Normal 5% 0
66:0 2.65 Flesh Normal 5% 0
2.45 Flesh Normal 50% 0
2.34 Flesh Regressed 90% Slight
2.30 Light gray Eroded 90% Severe
Yf Shape designation is normal for leaf-shaped, others described.
SCoating refers to percent of papillae showing some encrustation on their
/ Clumping refers to papillae adhered together in clumps.
A 105-day feeding trial was conducted with 24 steers to study the
comparative feeding value of a good quality dried citrus pulp and corn
and cob meal for fattening steers. These feeds singly or in combination
provided 66.6% of the concentrate mixture fed with approximately 1.5
pounds of long Bermudagrass hay fed per steer daily during the major
portion of the feeding trial. Average daily gains were 2.92, 2.98, 3.26
and 2.90 for the concentrate mixtures containing the ratios of 0:66.6,
22.2:44.4, 44.4:22.2, and 66.6:0 dried citrus pulp:corn and cob meal
respectively. No significant differences in gain were evident but those
steers receiving a combination of dried citrus pulp and corn and cob
meal tenrtod to have a higher dressing percent, more fat over the rib eye
and a higher carcass grade. Steaks from steers receiving dried citrus
pulp appeared to be more te:3.der as measured both by a four-member panel
and by the Warner-Bratzler Qhear. The ruminal papillae of steers fed
the two higher levels of dried citrus pulp were coated with necrotic
epithelium plus plant tissue. This was not apparent to any degree in
the other two lots of steers and its significance is not known.
A.O.A.C. 1960. Official Methods of Analysis. 9th Ed. Association of
Official Agricultural Chemists, Washington, D. C.
Anmerman, C..B., P. E. Loggins and L. R. Arrington. 1963. Comparative
feeding value of dried citrus pulp and ground snapped corn for fattening
lambs. Dept. of Animal Science Mimeo. Series No. 63-13.
Arnold, P. T. Dix, R. B. Becker and W. M. Neal. 1941. The feeding value
and nut.ritive properties of citrus by-products. II. Dried grapefruit
pulp for milk production. Fla. Agr. Exp. Sta. Bul. 354.
Becker, R. B. and P. T. Dix Arnold. 1951. Citrus pulp in dairy rations.
Fla. Agr. Exp. Sta. Cir. S-40.
Duncan, D. B. 1955. Multiple range and multiple F tests. Biometrics
Keener, H. A., N. F. Colovos and R. B. Eckberg. 1957. The nutritive
value of dried citrus pulp for dairy cattle. New Hampshire Agr. Exp.
Sta. Bul. 438.
Kirk, W. G. and G. K. Davis. 1954. Citrus products for beef cattle.
Fla. Agr. Exp. Sta. Bul. 538.
Peacock, F. M. and W. G. Kirk. 1959. Comparative feeding value of
citrus pulp, corn feed meal and ground snapped corn for fattening
steers in dry lot. Fla. Agr. Exp. Sta. Bul. 616.
Snedecor, G. W. 1956. Statistical Methods. 5th Ed. The Iowa State
College Press, Ames, Iowa.