Replacement value of dried citrus meal for corn meal in beef cattle diets

Material Information

Replacement value of dried citrus meal for corn meal in beef cattle diets
Series Title:
Bulletin University of Florida. Agricultural Experiment Station
Hentges, J. F
Place of Publication:
Gainesville Fla
Agricultural Experiment Stations, Institute of Food and Agricultural Sciences, University of Florida
Publication Date:
Physical Description:
22 p. : ill. ; 23 cm.


Subjects / Keywords:
Beef cattle -- Feeding and feeds -- Florida ( lcsh )
Dried citrus pulp ( lcsh )
Flour ( jstor )
Diet ( jstor )
Corn ( jstor )
bibliography ( marcgt )
non-fiction ( marcgt )


Bibliography: p.21-22.
General Note:
Cover title.
Bulletin (University of Florida. Agricultural Experiment Station) ;
Statement of Responsibility:
J.F. Hentges, Jr. ... [et al.].

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University of Florida
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University of Florida
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All applicable rights reserved by the source institution and holding location.
Resource Identifier:
027093567 ( ALEPH )
18363690 ( OCLC )
AEP0080 ( NOTIS )


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Introduction .. ___ ____ _________.. .._ ___ 3

Experimental Procedure ---.- --~_--_--..... ___... --_._ ....... ..._.____ 6

Results and Discussion ----..- _._....._............. ..___ ..____ .__ 7
Diet Composition --. _...... --- __-. .... ...... ....._.... 7
W eight Gains ---_.. -.._ .._... ..._ .._ .. .. ..__.-._ 9
Effect of Hay Restriction on Gains -......----. .._ 10
Feed Conversion to Gain ... .._....... 12
Rumen Microbial Fermentation -....----- -.... .-.._.-_.__ 12
Forestomach Changes --_-_.. .... ......___..............-____ .__.. 13
Carcass Data ...---.--- ------------... .... ... .. .. .... ... 16
Beef Fat Composition .......--_. --. -----.._-.......__- ..._...._ 17
Urinary Calculi ------------ ------.. -......___.-.. __._... ____.. _. 18

Summary of Research Results ------------------------------.. 19

Recommendations ------.-------_..... ... ..-. ._. .________ -______.__ _____._.... 20

Literature Cited _-----------.----_-..... ....-. .......... ..... 21

The authors acknowledge the cooperation of and extend their
thanks to the following who contributed to the accomplishment
of this project: Norris Cattle Co., Ocala, for cattle; Florida Feed
Mill, Jacksonville, for feed; Pasco Packing Co. for dried citrus
meal; F. A. Capote and Drs. M. T. Cabezas and C. B. Ammer-
man for assistance with chemical analyses; Dr. J. A. Olson for
gas chromatography facilities; and J. W. Burgess for feedlot



J. F. Hentges, Jr., J. E. Moore, A. Z. Palmer,
and J. W. Carpenter


Dried citrus meal is a by-product of the citrus fruit process-
ing industry. Its highest value is as an ingredient in livestock
feeds. It is obtained during the drying of citrus pulp by screen-
ing fine particles from the pulp. The production of dried citrus
meal in Florida was estimated (19)2 to be 8,000 tons in 1961,
a peak year for production. In Florida, it was estimated (12)
that about half of the total production of dried pulp originated
from oranges and half from grapefruit with very small quan-
tities from lemons, tangerines, and other fruits.
The appearance and composition of commercial sources of
dried citrus meal may differ widely because of the different
kinds of fruit being processed and the different methods used
to dry the residue peel, rag, and seed. The methods used for
drying most of the citrus fruit waste in Florida involve the
use of either direct fired driers or steam tube driers. In general,
steam drying results in the least charring.
The color of dried citrus meal may vary from golden yellow
to black depending on the amount of charring during dehydra-
tion. Figure 1 illustrates the variation in color and appearance
of commercial dried citrus meals. Charred, dark colored meals
are expected to possess a lower nutritional value than golden
yellow meals. To a lesser extent, color may be due to the quantity
of seed particles in the meal. Seed particles are desired in dried
citrus meal because of their higher content of protein and lipids.
The effect of kind and variety of fruit also may affect composi-
tion; for example, the percent seeds in dried citrus pulp may
1 Hentges, Associate Animal Nutritionist; Moore, Assistant Animal Nutri-
tionist; Palmer, Meat Scientist; and Carpenter, Associate Meat Scientist,
Animal Science Department, Florida Agricultural Experiment Station,
SNumbers in parentheses refer to Literature Cited.

Florida Agricultural Experiment Stations

_... '. Z1 4.- 9 '

ft. .: I.'_j

Figure 1.-Illustration of variation in color of commercial sources of dried citrus

vary from about 2.5 to 14 in orange pulp and from about 2 to 17
in grapefruit pulp. Commercial sources of dried citrus meal
also may vary in particle size from a desired consistency re-
sembling sawdust to one resembling fine black sand.
The nutritional value of dried citrus meal is expected to differ
according to color, composition, and consistency. High quality
dried citrus meal was reported by Kirk and Davis (12) to be
equal to dried citrus pulp in percentage of crude protein (6.46)
and to contain 1.0 percent more total digestible nutrients (71.9
vs. 70.9). The digestibility by cattle of nutrients in dried citrus
meal and dried citrus pulp was reported to be similar by Mead
and Guilbert (13), Neal et al. (15, 16), and Keener et al. (11).
In a feeding trial with yearling steers, Baker (5) reported that
steers ate high quality citrus meal more readily than citrus pulp
and gained slightly faster. He concluded that either citrus pulp
or meal was a satisfactory substitute for one-third of the ground
snapped corn in a ration containing approximately 40 percent
citrus molasses. Other publications by Pace (17), Baker (4),
and Jones et al. (10) resulted in recommendations being made
for many years to limit the use of citrus meal or pulp to only
a part of the diet for fattening steers because larger amounts
might lower gains, efficiency of feed conversion, and carcass

Replacement Value of Dried Citrus Meal

grade. The more recent publications by Ammerman et al. (1)
and Peacock and Kirk (18) reported no significant differences
in cattle weight gains, carcass grades, or feed efficiency when
66 to 70 percent of the ground snapped corn in diets was re-
placed by dried citrus pulp.
The outlook for an increased supply of dried citrus by-
products in Florida prompted research to learn the extent to
which a high quality steam-dried citrus meal could be used in
cattle fattening diets. It was predicted that cattle fattening diets
to be fed in the future would be "all-concentrate," probably
pelleted, mixtures with corn or citrus products as the major
energy sources and with the following ingredients included in
the formulas: molasses, urea, dehydrated alfalfa meal, an anti-
biotic, defluorinated phosphate, alkaline mineral mixture, and
vitamin premix (A and D). The diets fed to yearling steers in
the experiments reported herein were self-fed, pelleted, "all-
concentrate" mixtures of ingredients as shown in Table 1. The
objectives of the experiment were to measure the physiological
and economic effects when steam-dried citrus meal replaced 0,
25, 50, 75, and 100 percent of corn meal in pelleted diets.

Table 1.-Ingredient composition of diets.
Varying ingredients, pounds
Corn meal, yellow 72.0 54.0 36.0 18.0 0.0
Citrus meal, dried 0.0 15.8 31.6 47.4 63.2
Soybean oil meal, 44% 2.5 3.5 4.5 5.5 6.5
Cottonseed oil meal, 41% 2.5 3.5 4.5 5.5 6.5
Defluorinated phosphate 0.0 0.2 0.4 0.6 0.8
Fixed ingredients, pounds
Urea, 262% 1.0 1.0 1.0 1.0 1.0
Cane molasses, standard 5.0 5.0 5.0 5.0 5.0
Alfalfa meal, dehydrated 5.0 5.0 5.0 5.0 5.0
Mineral mixa 2.0 2.0 2.0 2.0 2.0
Corn cobs, ground 10.0 10.0 10.0 10.0 10.0
Aurofac 10b 0.0375 0.0375 0.0375 0.0375 0.0375
Vitamin premixed
Grass hayd
a Contained in percent: calcium, 18.9; phosphorus, 5.5; sodium chloride, 30; iron, 1.4; copper,
0.108; cobalt, 0.01; manganese, 0.48; and iodine, 0.01.
b Antibiotic source which added 3.8 milligrams chlortetracycline (aureomycin) per pound of
c Provided 1000 International Units (I.U.) vitamin A palmitate and 200 U.S.P. units vitamin
DV per pound of diet.
d Varied uniformly among lots from none to two pounds per day after initially allowing
ad libitum access for 14 days.

Florida Agricultural Experiment Stations


The experimental animals were yearling Hereford and Angus
steers which ranged in estimated slaughter grade from High
Utility to Standard at the beginning of the trial on December 19,
1962. They were kept in open sandy lots with shelter and shade
provided by numerous trees. One day before the trial, all were
drenched with 4 ounces phenothiazine fortified with iron, copper,
and cobalt. An implant of 24 milligrams diethylstilbestrol was
placed in the ear of each steer.
The steers were randomly assigned to five ration treatments
and were allowed free access to self-feeders containing the pellet-
ed rations which were described in Table 1. Low quality grass
hay was offered ad libitum in a different feeder. Later, the hay
allowance was varied and controlled. Although the steers had
access to trace mineralized salt in a covered mineral feeder, their
consumption of it was negligible. The dried citrus meal was
derived from oranges and was dried by steam. It was classified
as a high quality product comparable in apparent nutrient value
to dried citrus pulp. Proximate analyses of feed samples were
made according to methods of A.O.A.C. (2).
The ruminoreticulum (forestomach) contents were sampled
on the last day of the experiment by using suction on a rubber
stomach tube. The samples were filtered, preserved with mer-
curic chloride, and frozen until analyzed for volatile fatty acid
content by gas-liquid chromatography as described by Cabezas
et al. (6).
Live weights were recorded every 28 days. Gains in weight
were calculated on two final weight bases: feedlot scale weight
basis and empty body weight basis. For the latter, the wet
weight of the ruminoreticulum and its contents were subtracted
from the feedlot scale weight. This was done to eliminate mis-
leading variation due to "fill" in the forestomach. To calculate
dressing percent, feedlot scale weights were shrunk 3 percent.
At time of slaughter, the ruminoreticulum including its con-
tents was removed and weighed. A histological study of the
rumen epithelium was made on sections of the stomach wall
which were removed from the anterioventral part of the dorsal
sac about 2 inches from the esophogeal groove.
The carcasses were evaluated independently by University
and United States Department of Agriculture (USDA) person-

Replacement Value of Dried Citrus Meal

nel for USDA carcass grade and USDA carcass yield grade. The
degree of beef tenderness and juiciness was measured by a
trained four-member panel who tasted 1-inch thick, short loin
steaks broiled to an internal temperature of 165" Fahrenheit.
Samples of adipose tissue were taken from the layer of fat
which covered the 13th rib. The samples were rendered, filtered,
sealed in a carbon dioxide atmosphere, and frozen until analyzed.
The fatty acid composition of these samples was measured by
gas-liquid chromatography and reported in detail by Cabezas
et al. (6).
The incidence and description of urinary calculi were re-
corded from visual observation of bladders at the time of slaugh-


Diet Composition

A large variation among diets for content of crude fiber,
soluble carbohydrates, and calcium is shown in Table 2. As
the percent dried citrus meal in the diet increased, the content
of crude fiber increased and soluble carbohydrates decreased.
Although this shift in carbohydrates content from relatively
soluble to insoluble compounds had little effect on the gross
calorie content of the diets, it might be expected to shift micro-
bial fermentation toward a slower production of energy-yielding
volatile fatty acids in the ruminoreticulum.
Because dried citrus meal has a lower phosphorus and higher
calcium content than corn meal, the phosphorus content of all
diets was equalized by adding 0.2 percent defluorinated phos-
phate with each added increment of dried citrus meal. This re-
sulted in a range of calcium to phosphorus ratios from 1:1 to
3:1. Previous research by Dowe et al. (8) has shown that a 3:1
ratio is not wide enough to affect feedlot performance of steers
adversely, provided their phosphorus requirement is met. Even
though the phosphorus content of these diets was twice the
National Research Council minimum requirement (14), harmful
effects were not apparent.
The crude protein content of the diets was within the desired
range for all except the diet fed to cattle in lot V, which was
consistently 0.7 percent higher than expected in each shipment

Table 2.-Proximate nutrient composition of diets, percent.

Moisture-free basis

Lot Dry Crude Soluble Gross Ether Cal- Phos-
No. Corn Matter Nitrogena fiber CHOb energy extract Ash cium phorus

72 88.35 2.20

54 88.43 2.24

36 88.53 2.32

18 88.19 2.42

0 88.29 2.66

5.57 56.73 3.81

8.79 48.67 3.86

9.38 41.51 3.78

10.17 30.00 3.73

11.65 21.12 3.74

3.86 4.67

3.55 5.30

3.51 6.07

3.47 7.60

3.22 7.71





2.5:1 <


-_ C

a Multiplied by 6.25 gives crude protein values of 13.7, 14.0, 14.5, 15.1 and 16.6 percent on moisture-free or 12.1, 12.4, 12.8, 13.3 and 14.6 percent on air-dry
basis for lots 1 to 5, respectively.
b Soluble carbohydrates including starch, sugars and other carbohydrates hydrolyzed by 10 percent hydrochloric acid.
c Expressed in kilocalories of gross energy per gram of diet.

Replacement Value of Dried Citrus Meal

of the commercially-mixed feed. No explanation can be given
for this extra protein; however, it is unlikely that it affected the
performance of steers, since a level of 12 percent crude protein
in the diet was calculated to provide an adequate intake of diges-
tible protein.
The increase in ash content from diets I through V largely
reflects the high ash content of the citrus meal because only 0.2
percent of defluorinated phosphate was added with each in-
creased increment of dried citrus meal.

Weight Gains
Differences in average daily gain among lots were not sta-
tistically significant; however, the gain of cattle in lot V was
smaller than in other lots (Table 3). The magnitude of this
difference in weight gain would have been larger if two steers
had not been removed from this lot after 100 days for the pur-
pose of diagnosing the cause of poor performance. The gains of
these steers dropped to 0.9 and 0.8 pounds per day during the
42 days prior to their removal. They were the only steers in
the experiment which were gaining slowly. Examination of their
forestomachs revealed black, heavily-coated, apparently par-
akeratotic papillae in one and flesh-colored, regressed papillae in
the other. During the remaining 42 days of the trial, only one
more steer in the experiment dropped markedly in average daily

Table 3.-Summary of weight gain and feed conversion data.

Corn, percent 72 54 36 18 0
No. steers 14 15 15 14 12
Days in trial 142 142 142 142 142
Av. initial wt. lb.a 708 717 719 710 702
Av. final wt., lb.a 1075 1076 1064 1064 1027
Av. daily gain, lb.a 2.66 2.68 2.56 2.65 2.46C
Av. empty body wt., lb.b 1001 998 981 986 952
Adjusted av. daily gain, lb.b 2.04 2.14 2.00 2.14 1.99c
Lb. feed per Ib. gain (air dry basis) :
Concentrates 7.87 8.00 7.85 8.45 8.90
Hay 0.62 0.55 0.58 0.56 0.68
Total 8.49 8.55 8.43 9.01 9.58
a Initial weight shrunk 3 percent; final weight taken from feedlot scale, not shrunk.
b Initial weight shrunk 3 percent; final weight was empty body weight (final live weight less
weight of ruminoreticulum and its contents).
c The marked reduction in gain of three steers, subsequently removed from the trial after
100 days on feed, caused the average gain of lot V to be smallest.

Florida Agricultural Experiment Stations

gain, and he also was from lot V. His gain during the final 56
days was 1.28 pounds per day. Examination of his forestomach
revealed short (80 percent less than 8 mm) flesh-colored pa-
pillae, 90 percent of which showed a rust-colored coating on at
least 50 percent of their surface. It was estimated that 80 per-
cent of the rumen epithelium in their stomachs showed evidence
of depapillation or regression in size of papillae. These observa-
tions are interpreted as evidence that diets containing 63.2 per-
cent dried citrus meal may, at varying time intervals, cause the
rate of gain of susceptible steers to decrease sharply because of
damage to the rumen epithelium; however, the majority of steers
apparently were not affected adversely. Ammerman et al. (1)
reported smaller gains, smaller daily feed intake, and necrotic
rumen epithelium when non-pelleted fattening diets for yearling
steers contained 66 percent dried citrus pulp.

Effect of Hay Restriction on Gains
Because the acquisition and handling of hay or other rough-
ages in Florida is costly and because roughages are difficult to
process and mix into diets to be fed by self-feeders or automated
feeders, it is of prime importance to dev'.\l' ll-concentrate diets
which will be voluntarily consumed in desired quantities and
without digestive disorders. From days 17 to 44, the quantity of
hay eaten daily by cattle in all lots was reduced from average
intakes of 2.5 to 3.5 pounds per day when offered ad libitum to
an average intake of 0.5 pound per day. From days 45 to 58, hay
was not fed. Signs of distress were seen immediately in cattle
in all lots except lot V. Figure 2 illustrates the eating of bark
from trees by steers in lots I, II, III and IV. Apparently, they
were craving additional roughage or bulk in their rations.
Table 4 shows that the average daily gain of cattle in all lots
except lot V was sharply reduced when hay intake was restricted.
This observation points to a need for study of the possible sub-
stitution of citrus meal or pulp for roughage in all-concentrate
feed mixtures. Conversely, it illustrates the need for additional
bulk in pelleted mixtures consisting of corn meal or less than
47.4 percent dried citrus meal. Similar observations were re-
ported by Chapman et al. (7) who observed an increase in daily
feed consumption by yearling steier from 20.5 pounds of a ration
without hay to 25.6 pounds when 3.0 pounds grass hay was in-

Replacement Value of Dried Citrus Meal


Figure 2.-After hay was removed from the diets, the eating of bark from trees
occurred in all lots except lot 5 in which all corn meal was replaced by
dried citrus meal. The apparent cause was a craving for additional
bulk in the diet.

eluded in the ration. In another comparison, daily feed intake
was increased from 21.7 to 24.8 pounds by including 2.6 pounds
hay in the ration. Weight gains increased correspondingly. The
concentrate mixture offered to their steers was 48.8 percent
ground snapped corn and 40.0 percent dried citrus pulp which
is roughly comparable to lot IV in the experiment discussed

Table 4.-Comparison of average daily weight gains (ADG) during period of hay
restriction (day 17 to 58) and during entire 142 day trial.
Corn, percent 72 54 36 18 0
ADG, day 17-58, Ib.a 1.8 1.7 1.7 1.7 2.4
ADG, 142 day trial, lb. 2.6 2.7 2.6 2.6 2.5
a Hay was reduced from ad libitum offering to 0.5 pound per day from day 17 to 44 and none
was fed from day 45 to 58.

~J~ $~~ni


Florida Agricultural Experiment Stations

During the period that hay was not fed, several steers in lots
I, II, and III showed mild bloat. Three days after hay was re-
moved from the diet, one steer in lot I died suddenly with a
disease diagnosed as enterotoxemia. Twelve days after hay was
removed, one steer in lot II died with enterotoxemia suspected
on the basis of an incomplete diagnosis. It is known that this
disease, commonly called "overeating disease," is most prevalent
in cattle which have consumed large quantities of low-roughage,
high concentrate diets. Whether the larger content of bulky,
water-absorbent dried citrus meal fed to cattle in lots III, IV,
and V gave protection against this disease is only speculation,
but it seems logical because of the relative insolubility of the
carbohydrates in those diets and their probable effect on rumen
After day 58, hay was fed at the rate of 1.5 pounds per day;
all signs of distress disappeared and gains returned to their
previous rate.

Feed Conversion to Gain
The high efficiency of feed utilization by cattle in lots I, II,
and III was expected because of the high-concentrate, low-fiber
nature of their diets (Table 3). The decreased efficiency of feed
conversion by cattle in lots IV and V apparently reflected the
poorer utilization of the concentrate portion of those diets which
were largely dried citrus meal. This reduction of feed conversion
to weight gain was related to a lower content of soluble carbohy-
drates and a higher content of crude fiber in the diets. These
data indicate that about 50 to 100 pounds additional feed may
be required per 100 pounds of weight gain by yearling steers
when the diet consists of 47.4 to 63.2 percent dried citrus meal.

Rumen Microbial Fermentation
The rumen, first compartment of the forestomach in cattle,
is populated by billions of microbes, mostly bacteria and pro-
tozoa. They are responsible for the breakdown of feeds in the
foresto-mach and the production of chemical compounds which
are absorbed from the rumen into the bloodstream. The blood
transports these compounds to various tissues in the body to
permit growth and fattening. These compounds mostly are vola-
tile fatty acids (acetic, propionic, and butyric) which are pro-

Replacement Value of Dried Citrus Meal

duced by microbes in the forestomach. Because propionic acid
was shown by Armstrong and Blaxter (3) to be more efficiently
utilized for production of meat or milk than acetic acid, it was
of importance to measure the ratio of these acids produced
within the rumen from the different diets. The molar percent
and ratio of volatile fatty acids produced by bacterial and proto-
zoal fermentation of the diets fed to cattle in lots I, III, and V
are shown in Table 5. The addition of dried citrus meal increased
acetic and decreased propionic acid production. The change in
ratio of acetic to propionic acid was 1.13:1 to 4.35:1, a change
large enough to affect adversely the efficiency of utilization of
energy from the diets containing dried citrus meal. Armstrong
and Blaxter (3) have shown that the heat lost during the tissue
metabolism of propionic acid was less than for acetic acid.
Cabezas et al. (6) found that the increase of acetic acid in rumen
fluid was associated with a decrease in solubility of dietary car-

Table 5.-Molar percent and ratio of volatile fatty acids in rumen fluid samples
by stomach tube at end of trial.a
Lot No. I III V
Corn, percent 72 36 0
Acetate 44.9 56.4 69.2
Propionate 39.9 29.4 15.9
Butyrate 11.2 10.5 12.5
Valerate 2.1 1.5 1.5
Isovalerate 2.0 2.2 0.9
Acetate: propionate ratio 1.13:1** 1.92:1** 4.35:1**
** P < .01. Statistically highly significant.
a Concentrations of volatile fatty acids expressed as molar percentage of total in rumen

Forestomach Changes

The interior walls of the rumen in adult cattle are covered
with tongue-shaped projections called papillae. The size, shape,
and color of these papillae reflect the quantity and nature of the
diet which is being fed. A dense coating of large, flesh or gray
colored papillae indicates that an adequate supply of easily
digested food is being presented regularly to the bacteria and
protozoa in the rumen. Because chemical compounds are ab-
sorbed from the rumen through the papillae, their size and

Florida Agricultural Experiment Stations

number are proportional to the quantity of volatile fatty acids
and other compounds being produced. The physiological causes
for color and shape changes in rumen papillae are not known.
The combined weight of the reticulum and rumen compartments
of the forestomach, when adjusted to the live weight of the
animal, may be indicative of the amount of microbial activity
within the forestomach. Table 6 shows that the adjusted weight
(ruminoreticulum weight per 100 pounds empty body weight) of
the forestomach was slightly heavier in steers from lot V. Since
papillae density (numbers) and size were smaller in these
stomachs, the increased weight was attributed to adherent food
particles on the papillae and to increased musculature in the
ruminoreticulum wall.
The color of the papillae changed from a predominance of
gray on corn diets to dark brown on dried citrus meal diets. The

Table 6.-Summary of ruminoreticulum and papillae data.

Corn, percent 72 54 36 18 0
Ruminoreticulum weight, lb.a 22.2 25.1 23.3 23.1 25.2
Ruminoreticulum wt./EBWb 3.4 4.0 3.7 3.9 4.2
Papillae color:
Dark 2 3 0 4 7
Gray 8 6 1 7 3
Flesh 4 6 14 3 2
Papillae length, millimeters 15.4 15.6 13.8 13.9 14.2
Papillae width, millimeters 5.1 5.3 4.0 4.6 4.0
Papillae shape, incidence
Smooth 9 6 0 0 0
Serrated- 3 6 3 0 1
Serrated 2 3 6 4 4
Serrated+ 0 0 5 8 5
Irregular 0 0 1 2 2
Regressed papillae, incidence
30% 14 15 7 5 2
31 to 59% 0 0 7 5 5
60% 0 0 1 4 5
Encrusted papillae, incidence
30% 14 14 2 14 0
31-59% 0 1 6 1 1
60% 0 0 7 0 11
a Wet weight of ruminoreticulum at time of slaughter.
b Adjusted to 100 lb. empty body weight (live slaughter weight less weight of ruminore-
ticulum and its contents).
c Describes shape of perimeter of papillae; irregular being notched or deeply serrated in
in irregular patterns.
d, Spiralled,. eroded, club-shaped, and fragmented.
e.Papillae encased in a crusty coating except for 11 stomachs in lot V where coating
resembled a crusty mud which covered lower /3 rather than tip of papillae.

Replacement Value of Dried Citrus Meal

'0 5 SocA

0 2.5 5:0 75 Io0

Figure 3.-Illustration of differences in rumen papillae from forestomachs of
cattle fed diets in which dried citrus meal replaced the following per-
cent corn meal (left to right in photo) : none, 25, 50, 75, and 100.
Note the increase in encrustation or coating of papillae with increases
in level of dried citrus meal.

change in color was due to the encrustation or coating of the
papillae by some action or component of the dried citrus meal
diets. Figure 3 illustrates the differences in appearance of
papillae from steers fed each diet. The encrustation also pro-
duced histological changes, mainly parakeratinization, in the
epithelium on the papillae surface. This condition has been
termed "rumen parakeratosis" by Jensen et al. (9). Whether
this condition hinders the absorption of volatile fatty acids and
other dietary fractions is speculation, but it is logical to suspect
hindrance when 11 of 12 steers had more than a 60 percent inci-
dence of encrusted papillae and 10 of 12 steers had more than a
30 percent incidence of regressed papillae, as occurred in lot
V. Histological examination and chemical analyses revealed that
the encrusted brown material on the papillae was composed
largely of calcium and that the calcium was layered on the sur-
face being thickest near the tip of the papillae as shown in
Figure 4.
The change in shape from a predominately smooth or slightly
serrated perimeter of the papillae to a predominately deeply
serrated or irregular perimeter is assumed to be a result of the
increased abrasiveness of the dried citrus meal.

Florida Agricultural Experiment Stations

Figure 4.-Photomicrograph (X1080) of cross-section of a rumen papilla from
the forestomach of a steer fed dried citrus meal as 47.4 percent of his
diet. The dark layer on the surface is largely composed of a calcium

Carcass Data

When USDA standards for grading carcasses on the basis
of conformation and quality were used, the lot fed the diet con-
taining 63.2 percent dried citrus meal produced inferior car-
casses, because fewer were graded U.S. Choice (Table 7). Also,
the dressing percent of this lot was lower than in the other lots.
With each increased increment of dried citrus meal in the diet,
there was a decrease in thickness of backfat over the 13th rib
and a decrease in marbling score of the ribeye.
On the basis of USDA yield grade, which eliminates confor-
mation as a factor, lots fed diets containing 47.4 and 63.2 per-
cent dried citrus meal produced carcasses which were superior.
Likewise, the estimated yield of round, loin, rump, rib, and
chuck was largest and the thickness of backfat over the 13th rib
was smallest for carcasses in these two lots.
There were no differences among lots for tenderness or juic-
iness of steaks.
The current method of establishing carcass value on the basis
of USDA carcass grade caused cattle in lot V to have carcasses
of the lowest value; however, the yield of edible and palatable

Replacement Value of Dried Citrus Meal

Table 7.-Summary of carcass data.
Corn, percent 72 54 36 18 0
Dressing percent 59.9 59.0 59.3 59.2 58.3
USDA grade:
Choice 13 11 9 11 5
Good 1 4 6 3 7
USDA yield grade 3.4 3.7 3.6 3.2 3.0
Estimated yield, %c 49.8 49.1 49.4 50.3 50.8*
Marbling scored 13.4 12.1 12.3 11.6 11.3
Backfat, in. 0.52 0.48 0.46 0.39** 0.35**
Internal, fat, % 2.9 3.2 2.8 2.7 2.8
Ribeye area, sq. in. 11.8 10.8 10.8 11.3 11.1
Steak tenderness:
Shear test 7.52 7.40 6.59 7.59 6.94
Panel score 6.65 6.67 6.64 6.13 6.53
Juiciness score 5.82 5.82 5.97 5.96 5.99
* P < .05.
** P < .01.
a Based on feedlot scale weights shrunk 3 percent and 48-hour chilled carcass weight.
b Based on estimated percent yield.
c Estimated percent boneless, closely trimmed lean from round, rump, loin, rib, and chuck.
d Average small, small plus, and modest minus is represented by 11, 12, and 13, respectively.
e Rating from 1 to 13 (less than 8 is very tender) by Warner-Bratzler instrument.
f Rating from 1 to 9 (6 is above average, 7 is very tender) by trained taste panel.
g Rated from 1 to 9 (5 is average, 6 is very juicy) by trained taste panel.

meat may have been largest for cattle in this lot when one con-
siders the larger yield of primal cuts, smaller layer of backfat
to be trimmed, and equal tenderness.

Beef Fat Composition,

The content of saturated fatty acids in human diets is of
concern to medical doctors and their patients; consequently,
the alteration of the composition of beef fat toward a more un-
saturated state is desired. Table 8 shows that a highly signif-
icant change was recorded in fatty acid composition of backfat
over the 13th rib. Rib fat of steers fed diets containing corn
meal had a higher content of unsaturated oleic acid and a lower
content of saturated palmitic acid. Although the magnitude of
the difference between total saturated and unsaturated fatty
acids in samples within lots was only 1.0 percent for lot I, 2.6
percent for lot III, and 4.6 percent for lot V, the fact that the
fatty acid composition of depot fat in cattle can be changed by
the diet is of interest and to the credit of dried citrus meal.

Florida Agricultural Experiment Stations

Table 8.-Percent fatty acid composition of backfat over the 13th rib.
Lot No. I III V
Corn, percent 72 36 0
Myristic 6.3 6.4 6.9
Myristoleic 1.7 2.3 2.2
Palmitic 32.2 34.1 35.4**
Palmitoleic 4.9 5.2 6.0
Stearic 11.0 10.8 10.0
Oleic 41.9** 39.6 36.9
Linoleic 2.0 1.6 2.6
Saturated acids 49.5 51.3 52.3
Unsaturated acids 50.5 48.7 47.7
Iodine No. 46.0* 44.1 44.1
* P < .05.
** P < .01.

Urinary Calculi

A high incidence of urinary calculi (stones) had been ob-
served upon examination of bladders from steers in previous
experiments in which the diets contained large quantities of
dried citrus products. One explanation, based on opinion, was
that the high content of calcium in dried citrus products upset
the mineral balance, causing calculi formation. In this experi-
ment, defluorinated phosphate added to diets containing dried
citrus meal kept the phosphorus content equal in all diets and
kept the calcium to phosphorus ratio within a range of 1:1 to
3:1. No large urinary calculi were observed; consequently, the
mineral balance produced by this method of supplementation was
not calculogenic. The data on incidence of calculi reported in
Table 9 show traces of calculi in steers from all lots, but these
were very small, hard crystals of no apparent consequence be-

Table 9.-Incidence and quantity of urinary calculi by lots.
Corn, percent 72 54 36 18 0
Bladders examined, no. 14 15 15 14 12
Incidence, no. of steers
Negligible 1 6 4 3 1
Evidentb 1 3 0 0 0
Total 2 9 4 3 1
a Fewer than 6 clear crystals, less than 1 millimeter in diameter.
b Less than 1 cubic centimeter, of brown crystals approximately 2 millimeters in diameter.

Replacement Value of Dried Citrus Meal

cause the steers had been fed these diets for 142 days, which
exceeds the length of most drylot feeding periods.

Corn meal was replaced in pelleted, high-concentrate diets
for fattening steers by the addition of a high quality steam-dried
citrus meal plus sources of phosphorus and protein. Five lots
of yearling steers were self-fed these diets which contained the
following percentages of steam-dried citrus meal: 0, 15.8, ,31.6,
47.4, and 63.2.
Weight gains among lots at the end of the 142-day trial were
similar except for the lot which received a diet containing 63.2
percent dried citrus meal. This level produced gains equal to the
other lots for most steers but was not tolerated by a few sus-
ceptible steers whose weight gains declined.
Diets containing 0, 15.8, and 31.6 percent steam-dried citrus
meal were converted to weight gains with satisfactory and al-
most equal efficiency: 849, 855, and 843 pounds feed per 100
pounds gain respectively. Reduced efficiency of utilization was
recorded for diets containing 47.4 and 63.2 percent dried citrus
meal: 901 and 958 pounds feed per 100 pounds gain respect-
tively. The decreased efficiency of feed conversion correlated
with an increased acetic acid and decreased propionic acid per-
centage in rumen fluid. Restriction of hay intake lowered gains
on all diets except the one containing 63.2 percent dried citrus
With each increased increment of dried citrus meal in the
diet, there was increased evidence of an apparently harmful al-
teration of the rumen mucosa: papillae were darker, smaller,
and more. irregular in shape; papillae were partially coated or
encrusted and showed a high incidence of regression.
As the percent of dried citrus meal in the diet increased, the
dressing percentage, USDA carcass grade, marbling score, and
backfat thickness decreased, but the USDA carcass yield grade
and estimated yield of rib, loin, round, and rump increased. All
diets produced steaks of excellent and equal tenderness and
The percentage saturated fatty acid composition of backfat
was increased by the addition of steam-dried citrus meal to the

Florida Agricultural Experiment Stations


1. The appearance, composition, and feed value may be dif-
ferent for dried citrus meals obtained from different processors;
therefore, they should be inspected and valued accordingly.

2. Superior dried citrus meal will be golden yellow in color
with little or none that is charred or dark in color. It will be
bulky with little that is of a fine sand-like consistency. It will
contain a noticeable quantity of seed particles.

3. The pelleting of inferior, charred, dark-colored, dried
citrus meal will not improve its nutritional value as an ingred-
ient in a cattle-fattening diet.

4. Immediate changes in cattle diets from one source of
dried citrus meal to another may cause full-fed cattle to go "off
feed" and suffer digestive disorders. Changes should be made
gradually during a two- to three-week period.

5. Strive to keep the dried citrus meal portion of diets uni-
form in quality from week to week. If necessary, blend meals
from different sources. Avoid changing quickly from "old crop"
to "new crop," from variety to variety of fruit, from orange or
grapefruit to lemon, and from a low to high molasses content.

6. High quality steam-dried citrus meal, properly supple-
mented, can replace up to about 60 percent of corn meal and
comprise up to about 40 percent of formulas for fattening year-
ling cattle provided that the cattle are weighed periodically to
detect individuals whose gains are reduced by forestomach dis-

7. Decisions on percent of corn meal to be replaced by dried
citrus meal should be based on total feed required per unit of
weight gain in addition to relative prices. With each increase
in dried citrus meal above 40 percent, a decrease in efficiency of
feed conversion to weight gain should be expected.

8. The feeding of at least 1.5 pounds long or chopped hay oi
other bulky roughages is recommended with pelleted "all con-
centrate" diets containing less than 50 percent dried citrus meal.

Replacement Value of Dried Citrus Meal


1. Ammerman, C. B., P. A. van Walleghem, A. Z. Palmer, J. W. Carpen-
ter, J. F. Hentges, Jr., and L. R. Arrington. Comparative feeding value
of dried citrus pulp and ground corn and cob meal for fattening steers.
Animal Science Mimeo 64-8. 1963.

2. A.O.A.C. Official methods of analysis (8th ed.). Association for Official
Agricultural Chemists. Washington, D. C. 1955.

3. Armstrong, D. G., and K. L. Blaxter. Utilization of the energy of the
end products of ruminant digestion. Proc. Fifth International Congress
on Nutr. p. 74. 1960.

4. Baker, F. S., Jr. Fattening cattle in North Florida. Fla. Agr. Exp.
Sta. Bul. 505. 1952.

5. Baker, F. S., Jr. Citrus molasses, dried citrus pulp, citrus meal and
blackstrap molasses in steer fattening rations. No. Fla. Exp. Sta.
Mimeo 55-3. 1955.

6. Cabezas, M. T., J. F. Hentges, Jr., J. E. Moore, and J. A. Olson. Effect
of diet on fatty acid composition of body fat in steers. J. Animal Sci.
24:57. 1965.

7. Chapman, H. L., Jr., R. L. Shirley, and T. J. Cunha. Value of vitamins
A and E for fattening steers. Everglades Agr. Exp. Sta. Mimeo 63-19.

8. Dowe, T. W., J. Matsushima, and V. H. Arthaud. The effects of ade-
quate and excessive calcium when fed with adequate phosphorus in
growing rations for beef calves. J. Animal Sci. 16:811. 1957.

9. Jensen, Rue, J. C. Flint, R. H. Udall, A. W. Deem, and C. L. Seger.
Parkeratosis of the rumens of lambs fattened on pelleted feed. Amer.
J. Vet. Res. 19:277. 1958.

10. Jones, J. M., R. A. Hall, E. M. Neal, and J. H. Jones. Dried citrus
pulp in beef cattle fattening rations. Texas Agr. Exp. Sta. Bul. 613.

11. Keener, H. A., N. F. Colovos, and R. B. Eckberg. The nutritive value
of dried citrus pulp for dairy cattle. New Hampshire Agr. Exp. Sta.
Bul. 438. 1957.

12. Kirk, W. G., and G. K. Davis. Citrus products for beef cattle. Fla.
Agr. Exp. Sta. Bul. 538. 1954.

13. Mead, S. W., and H. R. Guilbert. The digestibility of certain fruit by-
products as determined by ruminants. I. Dried orange pulp and raisin
pulp. Calif. Agr. Exp. Sta. Bul. 409. 1926.

14. National Academy of Sciences -National Research Council. Nutrient
requirements of domestic animals, number 4. Nutrient requirements of
beef cattle. Publication number 1137. 1963.

15. Neal, W. M., R. B. Becker, and P. T. D. Arnold. Dried grapefruit ref-
use a valuable feed. Fla. Agr. Exp. Sta. Press Bul. 466. 1934.

22 Florida Agricultural Experiment Stations

16. Neal, W. M., R. B. Becker, and P. T. D. Arnold. The feeding value and
nutritive properties of citrus by-products. I. The digestible nutrients
of dried grapefruit and orange cannery refuses and the feeding value
of the grapefruit refuse for growing heifers. Fla. Agr. Exp. Bul.
275. 1935.
17. Pace, J. E. The feeding value of citrus by-products for growing and
fattening steers. M.S.A. Thesis, University of Florida. 1950.
18. Peacock, F. M., and W. G. Kirk. Comparative feeding value of dried
citrus pulp, corn feed meal and ground snapped corn for fattening
steers in drylot. Fla. Agr. Exp. Sta. Bul. 616. 1959.
19. Statistical Summary for 1962-63. Florida Canners Association, Winter