Front Cover
 Title Page
 Contributing authors
 Table of Contents
 Fundamental observations
 Rumenal fluid pH
 Effect on utilization of non-protein...
 Effects of citrus pulp on milk...
 Milk production on complete diets...
 Silage preservatives
 Distillers solubles
 Conclusions and recommendation...
 Back Cover
 Historic note

Group Title: Bulletin - Agricultural Experiment Stations, University of Florida ; 829
Title: Citrus feedstuffs for dairy cattle
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00027465/00001
 Material Information
Title: Citrus feedstuffs for dairy cattle
Series Title: Bulletin Agricultural Experiment Stations, University of Florida
Physical Description: 25 p. : ill. ; 23 cm.
Language: English
Creator: Wing, J. M ( James Marvin ), 1920-
Publisher: Agricultural Experiment Stations, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville Fla.
Publication Date: 1982
Subject: Dairy cattle -- Feeding and feeds -- Florida   ( lcsh )
Citrus fruits -- By-products -- Florida   ( lcsh )
Dried citrus pulp   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
Bibliography: Bibliography : p. 24-25.
Statement of Responsibility: J.M. Wing, editor.
 Record Information
Bibliographic ID: UF00027465
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000401515
oclc - 10680555
notis - ACE7363

Table of Contents
    Front Cover
        Front Cover
    Title Page
        Title Page
    Contributing authors
        Page i
    Table of Contents
        Page ii
        Page 1
    Fundamental observations
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
    Rumenal fluid pH
        Page 8
        Page 9
    Effect on utilization of non-protein nitrogen
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
    Effects of citrus pulp on milk production
        Page 15
        Page 16
    Milk production on complete diets and effect on young calves
        Page 17
    Silage preservatives
        Page 18
    Distillers solubles
        Page 19
        Page 20
        Page 21
    Conclusions and recommendations
        Page 22
        Page 23
        Page 24
        Page 25
    Back Cover
        Page 26
    Historic note
        Page 27
Full Text
November 1982


J. M. Wing, Editor

Agricultural Experiment Stations
Institute of Food and Agricultural Sciences
University of Florida, Gainesville
F. A. Wood, Dean for Research

Bulletin 829

J. M. Wing, Editor


J. M. Wing, R. B. Becker, H. H. Van Horn,
P. F. Randall, C. J. Wilcox, S. P. Marshall,
H. Roman-Ponce, G. E. Schaibly, F. J. Pinzon,
B. Harris, Jr., M. B. Olyaiwole, S. D. Sklare,
and K. C. Bachman


Introduction ...... ........ ............. ...... ... 1
Fundamental Observations .............................. 2
Rumenal Fluid pH .................................... 8
Effect on Utilization of Non-Protein Nitrogen ................ 10
Effect of Citrus Pulp on Milk Production .................... 15
Milk Production on Complete Diets ........................ 17
Effect on Young Calves ................................. 17
Silage Preservatives ................................. 18
Distillers Solubles .................................... 19
Conclusions and Recommendations ........................ 22
Acknowledgments ................ ................... 23
References ..................................... ...... 24


In 1911 the Florida Citrus Exchange established a fellowship for
research into uses of citrus waste and thus launched an area of in-
vestigation which remains strongly productive. The first publication
was in 1917 (20). Although much has been learned since, progress con-
tinues, and this bulletin will by no means be the final word.
In 1972 (5) research relating particularly to beef cattle was assembl-
ed for a publication which remains relatively complete; many of its
data are shared in principle with dairy cattle. Much specific dairy-
cattle research was in progress, however, at the time of publication,
and thus the purpose of this bulletin is to bring the subject matter up
to the present.
Involved primarily is citrus pulp, consisting mainly of the rag, peel,
and seeds of oranges with minor amounts from other fruits. This
waste collects on concrete slabs or in open pits at canneries. Cattle
will eat citrus pulp in the fresh state, but it accumulates too fast for
current consumption, and it ferments and spoils too rapidly to save
as it is produced. A small amount of fresh pulp is used, however, and
cattle consume it readily. They will, in fact, eat whole fruit as shown
in the cover illustration.
The obvious solution to spoilage was dehydration, and this was
tried first by Seth S. Walker using hardware cloth over boilers at the
Florida Citrus Exchange. The resulting product was fed to dairy cat-
tle by John M. Scott (15), and potential value began to be understood.
Further work by R. B. Becker (4) heightened interest to the point that
a citrus drying plant employing a rotary drum and direct flame was
established in Tampa.
Cannery residues went into the drum with no preparation other
than cutting. Charring and incomplete drying were common, and
the product often became moldy. Yet, even in this form, citrus pulp
was utilized readily by ruminants (11).
The process clearly needed improving. To this end, in 1934, calcium
carbonate was added to ground grapefruit peel. Within a few minutes
bound water was released from the residue. This method of bound
water release has been used ever since, with added improvements (9).
The residues are passed through shredders or hammermills reducing
them to pieces of about by 3 inches. Calcium hydroxide or oxide is
added before, during, or after cutting. This causes some desirable
chemical changes in the pectins and peel, resulting in release of the
bound liquids.

Pressing reduces the moisture to 65% to 75%. Drying takes place
in rotating drums as developed at Suni-Citrus Products Corpora-
tion (4) then dust is removed, and the remainder is separated into
pulp or meal. Most of the meal is pelleted and added to the pulp.
These hard conventional pellets, which often are mixed in small quan-
tities in conventional pulp, are not to be confused with pelleted citrus
pulp consisting of whole pieces which are compressed tightly but
never ground.
Chemists at Pasco Cooperative converted the press juice to
molasses about 1943. This product was investigated at the Universi-
ty of Florida, and its use as a new feedstuff was described in 1946 (2).
Often 20% to 50% of molasses is incorporated with the pulp. It
darkens the color somewhat and increases the content of soluble car-
bohydrates, with corresponding percentage decreases in fat, fiber and
Citrus molasses also serves as a substrate for fermentation in the
beverage-alcohol industry. The remaining distillery waste can be con-
densed to a very acceptable feedstuff high in pentose sugars and,
because of yeast used for fermentation, high in good quality protein.
The distillers solubles so produced may be incorporated into citrus
pulp, just as is whole molasses, or they can serve directly as an ingre-
dient of feed mixtures.
Citrus pulp usually is used as a source of energy because of its com-
position, as shown in Table 1. Fat and protein of citrus pulp vary with
the seed content, which ranges from 1.0% to 17.7% depending upon
the variety of fruit (9). The seeds are used efficiently (1). In fact, all
parts are utilized well (21), yet reports from the field persistently sug-
gest a limit to the use of citrus pulp, although there has been little
agreement on just what the limit is. This need for more precise infor-
mation prompted the following series of experiments in which each
succeeding one was based on previous results.

The investigations began with determinations of how citrus pulp
was used in the reticulorumen (first stomach compartment), because
this gives clues as to what one may expect in the way of animal pro-
duction responses. Subjects were rumen-fistulated steers. All diets in
the first experiment were '/ chopped alfalfa hay and 2/3 concentrates.
Citrus pulp in the concentrate portion varied from 0% to 60% (Table
2). All were fed to the limit of appetite with water offered free choice.
Digestibility was determined for dry matter, protein, and energy
by the chromic oxide method. Results are shown in Table 3.

Table 1. Average nutrient composition of dried citrus pulp (5).' b
Number of
Nutrient Analyzed Content

Moisture % 1728 8.58
Ash, % 1728 4.68
Ether extract, % 1728 3.74
Crude protein, % 1728 6.16
Crude fiber, % 1728 12.28
N.F.E., % 1728 64.56
Calcium, % 82 1.43
Phosphorus, % 82 0.11
Magnesium, % 82 0.12
Potassium, % 82 1.09
Sodium, % 82 0.096
Sulfur, % 10 0.066
Iron, ppm 35 98.72
Copper, ppm 35 6.19
Zinc, ppm 35 9.94
Manganese, ppm 35 5.70
Cobalt, ppm 10 0.073
aAnalyses were obtained by the Feed Laboratory, Division of Chemistry,
Florida Department of Agriculture, Tallahassee.
bAll mineral values are expressed on a dry matter basis.

Table 2. Air-dry composition of diets, experiment 1.
Ingredient 1 2 3 4 5
------------------------------ % ------------------------------
Cirtus pulp, dried 0 10.0 20.0 30.0 40.0
Corn, ground 32.7 22.0 11.2 0 0
Wheat bran 6.5 6.5 6.5 6.5 0
Cottonseed meal, 41%
protein 19.6 20.3 21.1 22.3 25.3
Dried brewers grain 6.5 6.5 6.5 6.5 0
Alfalfa, 17% protein 32.7 32.7 32.7 32.7 32.7
Salt .7 .7 .7 .7 .7
Defluorinated phosphate 1.3 1.3 1.3 1.3 1.3
100.0 100.0 100.0 100.0 100.0
a18% Ca, 21% P

Table 3. Digestibility of rations containing various levels of citrus
percent Treatment Means
Pulp Protein Dry matter Energy
----------------------------------------% ----------------------------------------
0 60.5 65.5 59.5
11 60.0 63.0 61.9
20 57.3 64.5 58.0
30 59.0 64.0 62.6
40 58.0 63.0 59.5

Digestibility appeared normal for high concentrate diets. Citrus
pulp had no significant effect on digestibility of the feed mixtures.
Likewise, no significant differences in rumenal acids occurred as a
function of time. Therefore, all samples from each diet were com-
bined. Mean molar percentages for. all treatments were acetic or C2,
65.9; propionic or C3, 14.8; butyric or C4, 14.4. Only traces of other
acids were observed. Acetates were somewhat high in all cases, and
there were no detectable differences due to citrus pulp level. This is
important because the acetates, or acetic acid (also referred to as C2),
are important precursors of milkfat. Thus, citrus pulp in the diet may
help keep the milk normal-even when roughage is poor in quality
and/or is supplied at a low level. It should be noted, however, that
this experiment did not include a diet which was particularly low in
It seemed possible, however, that pelleting of the pulp could affect
rumenal functions. The next experiment (21), therefore, involved the
effects of physical form of citrus pulp on fermentation patterns in the
rumen. All rations were /3 hay and 1/3 citrus pulp plus other ingre-
dients (Table 4). In diet 1 the pulp was in the conventional form.
Treatments 2, 3, and 4 involved replacing /3, %, or all conventional
pulp with pellets which were made without previous grinding.
Rumen-fistulated steers were used in each of the next two ex-
periments. There were four feeding periods in which each of eight
animals was assigned during each period to a diet which was different
from the one consumed previously by that particular animal. There
also were two replications of a 4 X 4 latin square which was balanced
for carry-over effects. Thus, each steer received each diet during two
different experimental periods.
Results were much like those of the previous experiment. Mean
molar percentages of rumenal acids for all treatments combined were
C2, 67.7; C3, 15.6; C4, 14.2; Cs valericc), 1.0; IC5 (isovaleric), 0.8. All

feeds were accepted readily, and all subjects appeared normal
throughout the trial. It was interesting that citrus pulp appeared,
because of its rumenal fermentation pattern (high and persistent C2
and more tendency than concentrates in general to maintain a
relatively high pH), to have roughage qualities. For this reason ex-
periment 3 compared citrus pulp to corn silage (13). Diets for experi-
ment 3 are displayed in Table 5. A single 4 X 4 latin square, balanced
for carry-over effects, was used to determine apparent digestibility of
protein, dry matter, and energy by means of total collection using
mature, rumen-fistulated Jersey steers. Preliminary adjustment
periods were 16 days, and collection periods were 5 days. Diet 1 con-
sisted entirely of corn silage; its consumption when fed once daily to
the limit of appetite was used to standardize the consumption of
other diets. Thus 1/s, 2/, or all dry matter of diet 1 was replaced by
citrus pulp in diets 2, 3, and 4.
Protein, dry matter, and energy were determined by standard
methods. An in vivo (in the living animal) cellulose procedure was

Table 4. Air-dry composition of diets used in experiment 2.
Ingredient 1 2 3 4
------------------------- ------------------------
Cirtus pulp, plain 33 22 11 -
Citrus pulp, pelleted 11 22 33
Soybean meal, 44% protein 26 26 26 26
Alfalfa hay, 17% protein 33 33 33 33
Oats 6.5 6.5 6.5 6.5
Salt .75 .75 .75 .75
Defluorinated phosphate .75 .75 .75 .75
a18% Ca, 21% P

Table 5. Composition of diets fed in experiment 3, dry basis.
-------------------------------- % --------------------------------
Cirtus pulp 0 27 55 82
Corn silage 82 55 27 0
Soybean meal 18 18 18 18
Protein 15.6 15.2 15.2 15.0
Energya 4551 4618 4540 4630

employed to study cellulose digestion. Two grams of dry ground
forage were placed in small nylon bags which were suspended for 24
hours in the rumen with nylon cord. Cellulose which disappeared was
considered to be digested, as shown in Table 6.

Table 6. Digestibility of dry matter, protein, energy, and cellulose
determined in experiment 3.
Citrus Dry
Pulp Matter Protein Energy Cellulosea
---------------------------------------------- % ----------------------------------------------
0 63.9 69.1 62.4 62.1
33 69.6 69.1 69.1 65.4
66 75.0 69.8 75.1 63.0
100 73.7 62.4 74.9 66.6
aNylon bag technique only.

To study rumenal fermentation the same steers were randomized
into another 4 X 4 latin square. There were two replications. During
the last 3 days of each test period, rumen samples were taken before
feeding and 1, 2, and 4 hours after feeding. They were analyzed for
rumenal volatile fatty acids as before.
Digestibility of diet 1 was significantly less than were diges-
tibilities of diets 2, 3, and 4. There were no significant differences be-
tween diets 3 and 4. Replacing 0%, 33%, 67%, and 100% corn silage
with citrus pulp resulted in diets with average apparent protein
digestibilities of 69.1%, 69.1%, 69.8%, and 62.4%. Statistical
analysis indicated that there was no evidence that diets 1, 2, and 3
differed, but that they were higher than diet 4. Citrus pulp alone is a
poor source of protein. When citrus pulp is combined with corn silage,
however, it appears that complementary functions make it adequate
in protein quality.
Apparent digestibilities of energy for Diets 1 through 4 were
62.4%, 69.1%, 75.1%, and 74.9%. Expressed as kilocalories of digesti-
ble energy per kilogram of dry matter, corn silage alone yielded 2,830
and citrus pulp alone yielded 3,468. At the '/ replacement level,
citrus pulp appeared to yield 4,127, assuming that digestibility of the
silage remained static. With the same assumption, it appeared to
yield 3,884 at the 2/ level. It was evident, therefore, that there was a
complementary effect between the two feedstuffs, as suggested by
Keener, et al. (10). Thus, citrus pulp seems to enhance and/or to be
enhanced by other feed ingredients with respect to ability to supply
productive energy and protein to cattle.

SC. P.
33.3% C. P.
66.6% C. P. -- ---
100% C. P. ...- ..
75 -

cc 70 -

-1 0 1 2 3 4

Fig. 1. Effect of citrus pulp on rumenal acetic acid.

Figure 1 shows also the changes in molar proportion of acetic acid
due to time after feeding. Mathematical equations for the curves were
used to analyze the results for possible significant differences. The
equations are shown in Table 7. These data show that for diets con-
taining various levels of citrus pulp, the molar percent of rumenal
acetic acid was equal to or greater than the rumenal molar percent
acetic acid of an all-corn-silage diet. This showed again that although
citrus pulp is a concentrate by definition, it has some important
roughage properties.
Generally, it is agreed with respect to molar proportions of VFA's
that high levels of acetate usually occur in animals fed diets contain-
ing large amounts of roughage, whereas lower levels are associated
with concentrates. However, it appears that citrus pulp does not
resemble other concentrates with respect to the molar percent acetic
acid produced (Figure 1). Previous publications (5) showed also that
citrus pulp fed in ruminant concentrate diets caused a marked in-
crease in the molar percent of acetic acid.
The regression equation for treatment 1 was significantly different
from the regression equations for the other three treatments (Figure
2). The only significant difference among the treatment means was
between treatments 3 and 4, four hours after feeding. Treatment 3
produced a higher molar percent of propionic acid (14.84) than those
usually reported for other feedstuffs, but present levels are similar to
trends noted previously (5).

Table 7. Regression equations of VFA for steers consuming experi-
mental rations.a

Acetic 4' Y,v = 69.6 + 1.51X -0.47X2 0.09
Acetic 3' Y,, = 64.5 1.35X +0.462 0.06
Acetic 2' Y,, = 70.0 2.30X +0.212 0.60
Acetic 1" Y, = 62.2 3.80X +0.84X2 0.32
Propionic 4' Y,v = 11.6 0.12X 0.02X2 0.01
Propionic 3" Y,, = 12.7 + 0.83X -0.07X2 0.12
Propionic 2" Y,, = 13.1 + 0.74X 0.15X2 0.07
Propionic 1" Y, = 12.3 0.84X -0.04X2 0.21
Butyric 4" Y,v = 17.2 0.84X +0.39X2 0.10
Butyric 3" Y,, = 20.7 + 1.49X -0.442 0.05
Butyric 2" Y,, = 17.3 + 0.65X -0.35X2 0.24
Butyric 1" Y, = 18.8 + 1.96X -0.35X2 0.13
Acetic/Propionic 4" Y,v = 6.18 + 0.23X -0.06X2 0.03
Acetic/Propionic 3" Y,,, = 5.48 0.43X +0.06X2 0.16
Acetic/Propionic 2" Y, = 5.60 0.45X +0.07X2 0.15
Acetic/Propionic 1" Y, = 5.95 0.95 + 0.22X2 0.36

aThe regression equations of VFA ratios having different superscripts were
judged to be different at the 0.05 level of significance, by use of orthogonal
bWhere Y = molar % of VFA at X hr., -1 < x s 4.

The acetic to propionic acid ratio displayed in Figure 3 was
significantly higher for treatment 4 (6.15) than for treatment 3 (4.66)
four hours post-feeding. There were no other treatment differences in
the acetic to propionic ratio. The maintenance of the relatively high
acetic to propionic acid ratio by feeding citrus pulp is in partial agree-
ment with the findings of Drude et al. (8), who reported combinations
with citrus pulp to be superior to roughages alone in maintaining
both milk production and milkfat percent.
Molar proportions of butyric acid were not affected by any of the
treatments, as shown in Figure 4. The only difference in molar per-
cent of butyric acid was 1 hour after feeding between treatment 3
(21.78) and treatment 4 (16.70 molar percent).


Significant differences in rumenal fluid pH were limited to
treatments 1 and 2 (Table 8). Treatment 1 resulted in pH values (7.26,
7.14, 7.06, 7.03) which were significantly higher than the other three

0 C. P.
33.3% C. P.
66.6% C. P. --
100% C. P. ..

-1 0 1 2 3

Fig. 2. Effect of citrus pulp on production of propionic acid.

0 C. P.
33.3% C. P.
66.6% C. P. -
100% C. P.

-1 0 1 2 3 4

Fig. 3. Effect of citrus pulp on rumenal acetic to propionic acid ratio.

treatments for all sampling times. The pH of rumenal contents pro-
duced by treatments 1 and 2 was significantly higher than for 3 or 4
at 1, 2, and 4 hours post-feeding, but was not significantly different
for the pre-feeding sampling. The treatment means of rumenal pH ap-
pear in Table 8.
Replacing corn silage with 67% or 100% of citrus pulp in the diet ef-
fected a reduction in the rumenal pH. As a general rule, it was higher
in animals fed a roughage-type diet than in those fed concentrates.
Increasing the levels of citrus pulp caused reduction in the rumenal

c c

Table 8. Rumenal pH treatment means for experiment 3.

Treatment Sampling Time
-1 hr. 1 hr. 2 hr. 4 hr.b

1 7.26 7.14 7.06 7.03
2 7.03 7.05 6.95 6.88
3 7.02 6.76 6.70 6.74
4 6.75 6.99 6.60 6.68

aOrthogonal treatment comparisons differing at P < 0.05: -1 hr., 1 hr. 1 vs. 2,
3, 4; 2 hr. and 4 hr., 1 vs. 3, 4.
b0 at time fed.

0 C. P.
33.3% C. P.
66.6% C. P.
100% C. P.

20 .


2 10 III
-1 0 1 2 3 4

Fig. 4. Effect of citrus pulp on rumenal butyric acid.

pH to an average of 6.81 for treatment 3 and 6.77 for treatment 4,
compared to values above 7 for treatment 1. These values are not
nearly as low as those generally resulting for high concentrate diets.
Thus, citrus pulp, though not considered a roughage in the strictest
sense, does contain roughage-like properties which, along with
relatively high concentrations of C2, promote a relatively high
rumenal pH as compared to concentrates in general.


It seemed possible that the particular pattern of citrus pulp
fermentation in the rumen may be conducive to efficient use of am-
monia and thus of protein and non-protein nitrogen sources, such as
urea. Coombe et al. (6) suggested that a highly fermentable substrate

minimized the rise in pH associated with rapid urea hydrolysis. This
may be pronounced if the fermentation pattern favors production of
acetate (7). It appears (14, 21) that citrus pulp is highly fermentable,
and that acetic acid is produced at a high and enduring level by its
rumenal digestion. Thus, it seemed possible that citrus pulp would
reduce the possibility of toxic effects of ammonia from diets which
are high in urea through some means of combining with it. Citrus
pulp may be conducive to efficient utilization of ammonia and thus
the efficient use of protein and non-protein nitrogen.
The subjects for the next phase of this work (experiment 4) were
eight rumen-fistulated steers (12). They were distributed randomly in-
to two 4 X 4 latin squares balance for carry-over effects. Diets fed in
experiment 4 are in Table 9. Citrus pulp in square 2 was pelleted
without being ground, whereas conventional unpelleted pulp was
used in square 1. All animals ruminated normally. Each steer con-
sumed 15 pounds (6.8 kg) of feed daily, thus receiving approximately
0.75 pounds (0.34 kg) urea. Following an adaptation of four weeks, all
steers were confined individually to pens in which they could move
freely. Before each sampling at 28-day intervals, they were kept in
stanchions for 12 hours. On these occasions, they were fed via rumen
fistulas. The rations were given in two equal portions during a 1-hour
interval. Time zero was considered to be 30 minutes after the first
feeding. Rumenal fluid and jugular blood were sampled at 1 hour
before and 2, 4, 7, and 12 hours after time zero. Volatile fatty acids,

Table 9. Air-dry composition of diets used in experiment 4.
Ingredient 1 2 3 4
-------------------------------- % --------------------------------
Corn 60.00 39.00 18.00 -
Citrus pulpa 19.00 38.00 55.00
Soybean meal 2.00 4.00 5.00
Urea 5.00 5.00 5.00 5.00
Sugarcane bagasse 33.33 33.33 33.33 33.33
Ca-P salt 1.00 1.00 1.00 1.00
Trace mineralized salt .67 .67 .67 .67
100.00 100.00 100.00 100.00

aThree rations with nonpelleted and three with pelleted citrus pulp (9.5 cm
bp 21%, Ca 16%, F 21%.
CMn 2500 ppm, Fe 2000 ppm, S 1000 ppm, Cu 330 ppm, Co 100 ppm,
I 70 ppm., Zn 50 ppm.

pH, and ammonia were determined in rumenal fluid. Multiple
covariance was used to test for significance of differences among
means and time trends. The two squares were analyzed separately
and pooled.
No difference between pelleted and nonpelleted pulp was detected,
except in ammonia time trends, and these did not result in differences
in treatment means. Therefore, the pooled analysis appeared most
valid. Rumenal pH for diet 1 was higher (P<.01) than for the other
three diets, and time trends also differed in that pH for the control
was higher during the first 7 hours (P < .01) (Table 10).

Table 10. Treatment means for squares 1 and 2 for rumenal pH and
ammonia-N and blood urea-N (experiment 4).
Sampling Time (hr.)a
Item Diet -1 2 4 7 12 Mean
Rumenal pH 1 7.26 7.23 7.18 6.49 6.06 6.84b
2 7.14 7.00 6.81 6.15 6.10 6.64
3 7.32 6.85 6.64 6.27 6.03 6.62
4 7.09 6.64 6.47 6.18 6.16 6.61
Rumenal 1 21.1 84.9 129.4 129.3 97.7 92.5
ammonia-N 2 43.4 126.3 146.6 118.0 98.2 106.5
(mg/100 mL) 3 22.6 105.7 141.3 113.2 78.8 92.3
4 26.2 110.4 141.0 107.1 70.6 91.1
Blood urea-N 1 42.31 55.33 71.94 84.28 82.06 67.18'
(mg/100 mL) 2 45.61 60.04 73.12 81.03 77.51 67.46
3 40.87 51.20 65.85 74.64 76.14 61.74
4 39.54 47.25 64.08 71.04 74.87 59.36

aRation given via fistula in two portions at 1-hr. interval. Time 0 was
0.5 hr. after first portion.
bl Vs 2, 3, 4 (P<.01).
c2 vs 3, 4 (P<.10).

Increasing citrus pulp from 0% to 19%, 38%, or 55% in the diets ef-
fected a reduction in rumenal pH (from 6.85 to 6.65, 6.61, and 6.51).
These pH values still were higher than usually occurs in ruminants
consuming high concentrate diets. The data agreed with previous
research in which citrus pulp was substituted for corn silage.
Although increasing citrus pulp caused reduction in rumenal pH, the
values for these diets were not quite as low as occurred in previous
work, probably because of the high urea and resulting ammonia
which may have neutralized some of the acid.

Statistical analysis of data for rumenal ammonia-N showed slight
differences in means (P<.10) between diet 2 vs 3, 4. The concentra-
tion of rumenal ammonia-N was higher in diet 2 than in the others.
There also were differences between time trends for diet 1 vs 2, 3, 4 in
which ammonia decreased more rapidly (P<.01) with increasing
levels of citrus pulp. Rumenal ammonia-N concentration was the only
response that showed significant differences (P<.05) due to form,
and this was in the time trends only. Pelleting resulted in less varia-
tion, but this did not affect treatment means. The maximal values for
rumenal ammonia occurred between 4 and 7 hours after feeding.
Levels as high as 220 mg per 100 mL at 7 hours after feeding resulted
in no signs of toxicosis. This may have been due to different pH
and/or fermentation patterns which tended to neutralize ammonia
through persistent production of acetic acid.
Diet 2 (19% citrus pulp) caused slightly higher blood urea-N than
did diets 3 or 4 (38% and 55% pulp) (P <.10), but the time trends were
not significantly different. It appears that high concentrations of
rumenal ammonia as such result in a net absorption of nitrogen, con-
version to urea, and loss from the animal via urinary excretion (19).
According to this concept, diets containing adequate nitrogen but
which result in low blood urea-N should result in retention of relative-
ly large quantities of nitrogen. The present data suggest that citrus
pulp at 38% to 55% increased nitrogen utilization since it decreased
urea nitrogen in blood. Thus, citrus pulp may help keep ammonia in
contact with the rumenal organisms which can convert it to protein.
No differences were detected in the molar percent of rumenal acetic
acid due to citrus pulp in the diets (Table 11). The time trend for the
control diet was different from those containing 19%, 38%, and 55%
citrus pulp, and that of diet 2 was different from 3 and 4 (P< .05).
Table 12 shows the pooled effects of citrus pulp on rumenal acids.
As expected high concentrate diets resulted in higher than usual pro-
pionate levels and less acetate. Both effects were less for diets con-
taining citrus pulp than for those with corn, but unlike previous
results, the effect on acetate was not significant statistically. This
may have been because so much of it had combined with ammonia
produced from the very high urea levels in all diets.
Treatment means for butyric acid did not differ, but the time trend
for diet 1 was different (P<.01) from those of 2, 3, and 4. Molar per-
cent butyric acid was not affected by citrus pulp in the diet at any
percentage. Ratios of rumenal acetic to propionic acid in steers fed
diet 1 were lower than those for diets 2, 3, and 4 (P<.01). This ex-
plains somewhat the results published previously by Drude et al. (8),
who showed that citrus pulp helped maintain normal milkfat tests.

Table 11. Experiment 4 treatment means for squares 1 and 2 with
respect to individual VFA.
Sampling Time (hr.)a
Diet -1 2 4 7 12 Mean
--------------.. ------------- molar % -------------------------------
Rumenal acetic 1 70.5 71.0 69.5 67.5 62.5 68.2
acid 2 73.0 70.0 71.0 67.0 68.0 69.8
3 75.0 68.0 76.5 70.5 71.0 72.2
4 74.0 67.5 68.5 68.0 70.0 69.6
Rumenal pro- 1 19.5 19.5 20.0 19.0 19.5 19.5b
pionic acid 2 16.5 19.0 18.5 18.5 17.0 17.9
3 15.5 19.5 20.5 15.5 15.5 17.3
4 15.5 19.0 18.5 17.0 16.0 17.2
Rumenal 1 10.0 9.5 10.5 13.5 18.0 12.3
butyric acid 2 10.5 11.0 10.5 14.5 15.0 12.3
3 9.5 12.5 12.0 14.0 13.5 12.3
4 10.5 13.0 13.0 15.0 14.0 13.1

aRation given via fistula in two portions at 1-hr. interval. Time 0 was
0.5 hr. after first portion.
bl VS 2, 3, 4 (P<.01).

Table 12. Pooled means for VFA concentration observed in experi-
ment 4.
Acetate Propionate Butyrate Acetate/ Total
Diet (C2) (C3) (C4) propionate %
----------------- molar % ----------------------
1 67.87 19.74 12.39 3.435" 82.56a
2 69.93 17.62 12.45 3.965 100.42
3 70.31 17.27 12.42 4.070 107.95
4 69.25 17.24 13.51 4.015 108.92

aOrthogonal comparisons (1 vs. 2, 3, 4) differed at P<.01.
bOrthogonal comparisons (2 vs. 3, 4) differed at P <.05.

Analysis of variance of total rumenal VFA showed that diet 1 gave
lower values than 2, 3, and 4 (P<.01), and diet 2 produced lower
rumenal VFA than 3, 4 (P <.05). Results are in Table 12. Following
the ingestion of a readily fermentable feedstuff, microbial activity in-
creases. Thus, the data suggest that, under conditions of this experi-
ment, citrus pulp served as a stimulus to rumenal fermentation as
compared to corn.

There were no differences between pelleted and nonpelleted citrus
pulp except for time trends in rumenal ammonia-N (P <.05). The data
agree with previous work (12) which indicates that pelleting does not
have the same general effect on citrus pulp as on other concentrate
feedstuffs. In this case, however, it must be remembered that the
pellets were made by compressing whole pulp which, when wet, as the
pellets become in the rumen, tend to resume the original form of the
conventional pulp.


Keener et al. (10) showed that citrus pulp was a good source of
energy but possible effects of pelleting needed clarification. To this
end the milk production and composition were compared under two
regimens which were drastically different in roughage portion of the
diet and in the form of citrus pulp (Table 13). Although different
animals were used in each trial, it was not possible to conduct
simultaneous trials. Thus, the marked difference in milkfat between
roughage groups may not be as important as indicated by data
displayed in Table 14. In all cases milk was normal, and no difference
could be attributed to physical form of citrus pulp. In general, data in
Table 14 show that citrus pulp should be limited for dairy cattle ra-
tions only by economic considerations and composition of other in-
gredients. It may be especially valuable in low roughage diets
because citrus pulp tends to produce a large proportion of acetate.
Nutritionally, pelleted pulp and the conventional form appear to be
the same.

Table 13. Composition of rations fed in experiment 5.
Ingredient 1 2 3 4
------------------------ % ------------------------
Pangola hay 33 33
Sugarcane bagasse 25 25 -
Citrus pulp, plain 35 35 -
Citrus pulp, pelleted 35 35
Ground corn 28 28 20 20
Soybean meal, 44% protein 10 10 10 10
Defluorinated phosphate .75 .75 1.1 1.1
Salt .75 .75 .4 .4
Urea .5 .5 .5 .5
100 100 100 100

Table 14. Effects of pelleting citrus pulp in complete rations with different roughage on production and composition
of milk from Guernsey cows.
Solids Titratable
Milk Fat Protein Not Fat Acidity Chloride
Roughage Pulp (kg) (%) (%) (%) (%) (%)
Suarcane baasse lain 17.3 3.7 3.2 9.01 .150 .164
Sugarcane bagasse
Pellets 17.4 3.7 3.2 9.01 .151 .157
Plain 14.8 4.4 3.3 9.03 .143 .168
Pangola hay Pellets 14.6 4.6 3.3 9.17 .147 .163


The principles discovered during the earlier experiments were ex-
citing, but there remained a need for developing them into practices
of feeding. To this end, citrus pulp level was factored into yet another
investigation of complete diets for lactating cows (16). The levels
were 43.1% or 8% of citrus pulp as a component of complete diets.
Milkfat was 4.16% for the diet containing 43.1% pulp whereas it was
only 3.57% for the diet containing 8% pulp. This effect was expected
from previous work. Rumenal fermentation patterns were not deter-
mined, but it seemed quite likely that the role of citrus pulp in main-
taining the fat test was a function of the high and enduring levels of
rumenal acetates which are a function of dietary citrus pulp. This con-
firms further the similar results of Drude et al. (8), who reported the
same phenomenon but without an explanation, since the fundamen-
tals of rumenal digestion of citrus pulp were not known to them. In a
further experiment (13) with sugarcane bagasse complete rations, the
results were more like those of experiment 5, which were not analyzed
for significance of the effect of roughage on fat test (Table 13). The
acetate/propionate ratio was normal in the latter experiment, but, as
in the previous one, low fat tests occurred throughout. Thus, factors
other than the rumenal fermentation pattern observed in these ex-
periments appear to affect milk composition in cows fed complete ra-
tions which are high in sugarcane bagasse. The role of citrus pulp
with respect to milk fat production appears to be through
maintenance of normal acetate, and that is not always enough to pre-
vent abnormalities, since other factors also may be involved with
diets containing poor-quality roughage.


The next experiment was based in part on reports from the field
which suggested that citrus pulp should be limited for small calves,
although a low level had been shown to be desirable (22). Diets con-
taining 30% of citrus pulp with and without cottonseed hulls were
formulated as shown in Table 15. These were fed from birth through
80 days. Consumption of diet 2 containing 15% hulls and 15% pulp
significantly exceeded all others as shown in Figure 5. It is in-
teresting, however, that as the experiment progressed past 60 days,
diet 1, which contained 15% cottonseed hulls and 30% citrus pulp,
was consumed in increasing amounts, and thus its total consumption
for the entire experimental period closely approached that of diet 2.
The growth of calves on diet 1 improved even more than should be ex-
pected from the increased feed consumption (Figure 6), thus showing

Table 15. Composition of calf starter rations.
Ingredient 1 2 3 4
---------------------------------% --------------------------------
Cottonseed hulls 15.0 15.0 -
Citrus pulp 30.0 30.0 -
Ground shelled corn 24.0 55.0 41.0 71.0
Soybean meal (48%) 24.0 22.0 22.0 21.0
Molasses 5.0 5.0 5.0 5.0
Salt, trace min. 1.0 1.0 1.0 1.0
Dicalcium phosphate 1.0 .5 1.0 .5
Ground limestone 1.5 1.5
100. 100. 100. 100.
Estimated crude
protein % 16.5 16.5 16.5 16.5
Estimated crude fiber % 11.2 8.2 5.1 2.0
Estimated calcium % .80 .81 .77 .79
Estimated phosphorus % .42 .41 .48 .43

aAll rations were fortified, per 454 g of starter, with vitamin A, 2500 I.U.;
vitamin D, 300 I.U.; Aureomycin or Terramycin, 10 mg.

again the previously demonstrated complementary effects. Citrus
pulp appears to be advisable in rations for calves over two months
old, but because of acceptability factors not for younger ones, at least
under conditions of this experiment.


Citrus pulp, meal, and molasses alone and in various combinations
have served as silage preservatives (2). The molasses was used effec-
tively at levels of 40 pounds per ton for grasses and 70 pounds for
legumes. This is similar to the effects of other types of molasses.
Citrus products also added to acceptability of the final product and
improved efficiency of preservation. Pulp and meal are very absorp-
tive, and thus citrus pulp in the present research absorbed as much as
145% of its original weight in juices containing valuable nutrients
which otherwise would have seeped out of the silo and been lost. Ab-
sorption increased with each increment of citrus pulp to 250 pounds
per ton. The increase dropped off rapidly above 150 pounds, however,
and, therefore, 150 pounds per ton appeared to be the most feasible

(3.5) Hulls 15%, C. P. 30%
Hulls 15%, C. P. 15% -- -
S 6.1 Hulls C. P. 40% --
a (3.0) Hulls 0, C. P. O.
Z /
0 5.5
. (2.5) /

O 4.4 /
S(1.5) //
0 / /
os 2.2 /
Q- (1.0) //
I 11 / .7
(0.5) ,/Il

10 20 30 40 50 60 70 80

Fig. 5. Effect of cottonseed hulls and citrus pulp and feed intake by

Large and increasing amounts of citrus molasses are used for pro-
duction of beverage alcohol. The remaining sugars, which are pen-
toses, cannot be used by the beverage industry, but they are an ex-
cellent source of energy for cattle. In addition valuable minerals and
residual yeast from fermentation made the material left after distill-
ing a potential feedstuff. It is condensed to the consistency of
molasses and is thus designated as citrus molasses distillers solubles
In common with citrus pulp but unlike many other liquid
feedstuffs, CMDS resulted in improved digestibility of other ingre-
dients of the diet. Since the effect occurred only at a level of 6% of
dietary dry matter, one may consider 6% optimal (Table 16).
Ruminal fluid was assayed for acetic, propionic, and butyric acids,
ammonia nitrogen, and pH. Significant treatment effects were found








Hulls 15%, C. P. 30%
Hulls 15%, C. P. 15% ----
Hulls O, C. P. 30% -..-..
Hulls 0, C. P. 0.

10 20 30 40 50 60

70 80

Fig. 6. Effect of cottonseed hulls and citrus pulp on body weight of

for all. Molar percent of acetic acid increased linearly with increase in
CMDS percent (P < .05). Propionic acid responded with peak values
reached at the 6% level. Acetate/propionate ratios also showed
significant effects with the most favorable values at the 6% treat-
ment level (Table 17).

Table 16. Treatment means for coefficients of digestibility for dry
matter, crude protein, and acid detergent fiber as a func-
tion of CMDS level in the diet of steers.
Dry Organic Crude Detergent
Treatment % CMDSa Matter Matter Protein Fiber

1 0 64.38 66.03 53.72 45.39
2 6 68.99b 70.43b 51.97 43.50
3 12 62.36 63.66 50.40 43.61
4 18 55.27 57.02 49.41 41.19

Citrus molasses distillers solubles, percent of diet dry matter.
Significant at P <.01.

Table 17. Effect of citrus molasses distillers solubles on ruminal
acetic acid.a

%C-MDS Hours After Feeding

-1 Ob 1 3 5 7 11
0 61.13 57.04 58.37 52.22 59.39 56.99 57.52
6 65.52 55.12 57.90 57.55 56.13 55.96 58.03
12 63.89 59.35 59.98 60.54 60.52 58.58 60.48
18 65.66 60.75 58.79 64.07 60.64 60.42 61.72
64.05 58.07 58.76 58.59 59.17 57.98 59.44

aSignificant linear effect, P<.01.
bImmediately after feeding.

In the last experiment of the present series the main objective was
to determine the effects of CMDS on daily milk production and com-
position and on dry matter intake. CMDS caused increased milk pro-
duction as shown in Figure 7. At the 6% level of CMDS, dry matter
intake and intake as a percent of live body weight increased (P <.05)
and milk composition was unaffected.



S 46 -
a 44
-E (20.0)



C-- --

Cottonseed Hulls
- ---------------

3 6

Fig. 7. Effect of citrus molasses distillers solubles on daily produc-
tion of 4% fat corrected milk by cows on complete diets with
either corn silage or cottonseed hulls.


Experimental results and observations warrant the following con-
clusions and recommendations for use of some citrus by-products in
dairy cattle feeds.
1. Citrus pulp has no properties other than its nutrient content,
which limits its use in dairy cattle concentrate rations. Thus, it may
be used at any level at which it can be included without causing a
nutritional imbalance. One must remember, however, that this re-
quires special attention to the calcium-phosphorous ratios, which are
extremely wide in citrus pulp because of the calcium added during
processing. A level of 40% of the total ration is feasible.
2. Citrus pulp is not a roughage and cannot be so used even in
diets for small calves.
3. Citrus pulp, although a concentrate, has roughage-sparing
qualities. Thus, because of its tendency to keep acetate levels and pH
in the rumen high, it tends to prevent low milkfat and metabolic pro-
blems on fiber-deficient rations.
4. Factors other than the rumenal production of acetate appear to
be involved in production of abnormal milk on rations lacking in
roughage, and in these cases, citrus pulp may help but cannot entirely
prevent low milkfat tests.
5. Pelleting does not change the nutritional properties of citrus
pulp, probably because grinding is not necessary. Thus, after the
pellets are soaked in rumenal fluid, they expand, and so their
physical properties are not much different from conventional pulp
under similar circumstances.
6. When citrus pulp is added to forage at ensiling, it has three
desirable effects: (a) extra energy becomes available; (b) nutrient con-
taining juices are absorbed, and thus their loss is prevented; and (c) a
desirable medium for bacterial fermentation is supplied.
7. Citrus pulp is a good ingredient in rations for calves from two
months of age but not always for younger ones. It is highly accep-
table to older animals, but it depresses feed intake of young calves
when used to replace cottonseed hulls or to supplement them.
8. Citrus pulp is highly compatible with urea in cattle rations and
thus in rations containing urea, it may be used in about the same way
as is corn.
9. Except for small calves, citrus pulp is a positive factor in ac-
ceptability, since cattle like it, and it tends to mask undesirable
flavors such as that of urea.
10. Citrus pulp is a good source of energy as such, and it appears to
interact with some other feedstuffs in a way which makes both more
digestible. It is not a good source of protein, but it does complement

protein utilization of some other feedstuffs.
11. Citrus molasses is somewhat different from cane molasses, but
in general it may be used for the same purposes and in about the same
way as by-product molasses from other industries.
12. Citrus molasses distillers solubles at 6% of the total diet pro-
motes digestion, a favorable type of fermentation, and the proper
rumenal environment for utilization of other ingredients, including
non-protein nitrogen. This feedstuff is an excellent source of protein,
probably because of residual yeast. There is no significant effect on
milkfat, milk protein, or on body weight changes. It appears that the
effect on milk production results at least in part by stimulation of ap-
petite by the distillers solubles.


The authors express their appreciation to the Florida Citrus Com-
mission and to Florida Distillers, Inc., for partial funding of this
work. Graduate students, visiting professors, and employees of the
University of Florida also contributed in many ways. Particularly
outstanding contributions came from Randall Griffin, Alfonso
Castro, and John Boggs.


1. Ammerman, C. B., and J. M. Wing. 1963. Fla. Agr. Exp. Sta.
Dairy Science Mimeo 63-5.

2. Becker, R. B., P. T. D. Arnold, G. K. Davis, and E. L. Fouts. 1946.
Citrus molasses. Fla. Agr. Exp. Sta. Press Bul. 423.

3. Becker, R. B., J. M. Wing, P. T. D. Arnold, J. T. McCall, and C. J.
Wilcox. 1970. Silage investigations in Florida. Fla. Agr. Exp.
Sta. Bul. 734.

4. Becker, R. B. 1978. Personal communication.

5. Chapman, H. L., Jr., C. B. Ammerman, F. S. Baker, Jr., J. F.
Hentges, B. W. Hayes, and T. J. Cunha. 1972. Citrus feeds for
beef cattle. Fla. Agr. Exp. Sta. Bul. 751.

6. Coombe, J. B., D. E. Tribe, and J. W. C. Morrison. 1980. Some ex-
perimental observations on the toxicity of urea to sheep.
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7. Davis, G. K., and H. F. Roberts. 1969. Urea toxicity in cattle. Fla.
Agr. Exp. Sta. Bul. 611.

8. Drude, R. E., J. R. Escano, and L. L. Rusoff. 1971. Value of com-
plete feeds containing combinations of corn silage, alfalfa
pellets, citrus pulp and cottonseed hulls for lactating cows. J.
Dairy Sci. 54:773.

9. Hendrickson, R., and D. W. Kesterson. 1965. By-products of
Florida citrus. Fla. Agr. Exp. Sta. Bul. 698.

10. 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.

11. Neal, W. M., R. B. Becker, and P. T. D. Arnold. 1935. The feeding
value and nutritive properties of citrus by-products. 1. The
digestible nutrients of dried grapefruit refuse for growing
heifers. Fla. Agr. Exp. Sta. Bul. 275.

12. Pinzon, F. J., and J. M. Wing. 1976. Effects of citrus pulp in high
urea rations for steers. J. Dairy Sci. 59:1100.

13. Randel, P. F., H. H. Van Horn, C. J. Wilcox, H. Roman-Ponce,
S. P. Marshall, and K. C. Bachman. 1975. Supplemental
nitrogen by the metabolizable protein concept. J. Dairy Sci.

14. Schailbly, G. E., and J. M. Wing. 1974. Effects of roughage con-
centrate ration on digestibility and rumen fermentation of
corn silage citrus pulp rations. J. Anim. Sci. 38:697.

15. Scott, J. R. 1926. Grapefruit refuse as a dairy feed. Fla. Agr. Exp.
Sta. Ann. Rept. 25R-26R.

16. Van Horn, H. H., S. P. Marshall, C. J. Wilcox, P. F. Randel, and
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corn substitutions. J. Dairy Sci. 58:1101.

17. Sklare, S. D. 1981. Nutritional evaluation of citrus molasses
distillers solubles for dairy cattle. Unpublished.

18. Van Horn, H. H., M. B. Olayiwole, C. J. Wilcox, Barney Harris,
Jr., and J. M. Wing. 1976. Effects of housing, milk feeding
management, and ration formulation on calf growth and feed
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19. Waldo, D. R. 1968. Symposium: Nitrogen utilization by the rumi-
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20. Walker, S. S. 1917. The utilization of cull citrus fruits in Florida.
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21. Wing, J. M. 1975. Effects of physical form and amount of citrus
pulp on utilization of complete feeds for dairy cattle. J. Dairy
Sci. 58:63.

22. Wing, J. M. 1965. A new way to feed calves. Feedstuffs 37:28.

^^^^^^^ I B^

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