• TABLE OF CONTENTS
HIDE
 Front Cover
 Credits
 Table of Contents
 Historical
 Plan of investigation
 Experimental results
 Discussion of results
 Summary and conclusions
 Acknowledgement
 Literature cited














Group Title: Bulletin - University of Florida Agricultural Experiment Station ; 354
Title: Feeding value and nutritive properties of citrus by-products
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Permanent Link: http://ufdc.ufl.edu/UF00027677/00001
 Material Information
Title: Feeding value and nutritive properties of citrus by-products
Series Title: Bulletin - University of Florida Agricultural Experiment Station ; 354
Physical Description: Book
Language: English
Creator: Neal, W. M.
Arnold, P. T. Dix
Becker, R. B.
Publisher: University of Florida Agricultural Experiment Station
Publication Date: 1941
 Record Information
Bibliographic ID: UF00027677
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.

Table of Contents
    Front Cover
        Page 1
    Credits
        Page 2
    Table of Contents
        Page 3
    Historical
        Page 3
        Page 4
        Page 5
        Page 6
    Plan of investigation
        Page 7
    Experimental results
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
    Discussion of results
        Page 12
    Summary and conclusions
        Page 13
    Acknowledgement
        Page 13
    Literature cited
        Page 14
Full Text


February, 1941


UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATION
WILMON NEWELL, Director
GAINESVILLE, FLORIDA

The Feeding Value and Nutritive

Properties of Citrus By-Products

II. Dried Grapefruit Pulp For Milk Production
P. T. Dix ARNOLD, R. B. BECKER AND W. M. NEAL


Fig. 1.-Countess, a purebred Jersey in the Experiment Station herd,
relishes a meal of citrus pulp, after having had it daily in her ration
for six years.
Single copies free to Florida residents upon application to the
AGRICULTURAL EXPERIMENT STATION
GAINESVILLE, FLORIDA


Bulletin 354








EXECUTIVE STAFF
John J. Tigert, M. A., LL.D., President
of the University'
Wilmon Newell, D.Sc., Director'
Harold Mowry, M. 5. A., Asst. Dir.,
research
J. Francis Cooper, M.S.A., Editor'
Jefferson Thomas, Assistant Editor'
Clyde Beale, A.B.J., Assistant Editors
luI Kieeuig Crebap, Librarian
Ruby Newhall, Administrative Manager'
K. H. Graham, Business Manager3
Rachel McQuarrie, Accountant
MAIN STATION, GAINESVILLE
AGRONOMY
W. E. Stokes, M.S., Agronomist1
W. A. Leukel, Ph.D., Agronomists
Frcd. H 1-1 1, Ph D.. Agionomist
G. E. Ritchey, M.S., Associate2
W. A. Carver, Ph.D., Associate
Jouli P. Caimp, M.S., Assistant
Roy E. lascr, M.S., Assistant
Fred A. Clark, B.S.A., Assistant
ANiI.IAL INDUSTRY
A. L. Sleuly, D.V.M., Animal Indus-
triallslt
R. B. Becker, Ph.D., Dairy Husbandman'
E. L. Fouts, Ph.D.. Dairy Technologists
W. M. Neal, Ph.D. Asso. In An. Nutrition
D. A. Sunders, D.V.M., Veterinarian
M. W. Emmel, D.V.M., Veterinarian3
N. R. Mehrhof, M.Agr., Poultry Hus-
bandman3
W. G. Kirk, Ph.D., Asso. An. Husb.3
T. R. Freeman, Ph.D., Asso. in Dairy
Manufactures
D. J. Smith, B.S.A., Asst. An. Husb.
P. T. Dix Arnold, M.S.A., Asst. Dairy
Husbandmans
L. L. Rusoff, Ph.D., Asst. in An.
Nutrition'
O. W Anderson, M.S., Asst. Poultry
Husbandman*
L. E. Mull, M.S., Asst. in Dairy Tech.
SOILS
R. V. Allison, Ph.D., Chemist'x
Gaylord M. Volk, M.S., Chemist
F. B. Smith, Ph.D., Microbiologists
C. E. Bell, Ph.D., Associate Chemist
H. W. Winsor, B.S.A., Assistant Chemist
J. Russell Henderson, M.S.A., Associate'
L. H. Rogers, M.S., Asso. Biochemist
Richard A. Carrigan, B.S., Asst. Chemist
ECONOMICS, AGRICULTURAL
C. V. Noble, Ph.D., Agricultural
Economist' -
Zach Savage, M.S.A., Associate
A. H. Spurlock, M.S.A., Associate
ECONOMICS. HOME
Ouida D. Abbott, Ph.D., Home Econ-
omist'
Ruth Overstreet, R.N., Assistant
R. B. French. Ph.D.. Asso. Chemist
ENTOMOLOGY
J. R. Watson, A.M., Entomologist3
A. N. Tissot, Ph.D., Associate
H. E. Bratley. M.S.A.. Assistant
HORTICULTUR E
G. H. Blackmon, M.S.A., Horticulturist'
A. L. Stahl. Ph D.. Associate
F. S. Jamison, Ph. D., Truck Hort.'
R. J. Wilmot, M.S.A., Fumigation
Stecia li i
R. D. Dickey, M.S.A., Asst. Horticulturist
J. Carlton Cain, B.S.A., Assistant
Horticulturist
Victor F. Nettles, M.S.A., Assistant
Horticulturist
F. S. Laeasse, Ph.D., Horticulturist'
H. M. Sell Ph Ac"n Horticulturist'
PLANT PATHOLOGY
W B Tisdale Ph D. Plant Pathologist'
George F. Weber, Ph.D., Plant Path.'
L O Gratz. Ph D., Plant Pathologist
Erdman West. M.S., Mycologist
Lillian E. Arnold, M.S., Asst. Botanist


BOARD OF CONTROL
H. P. Adair, Chairman, Jacksonville
W. M. Palmer, Ocala
R. H. Gore, Fort Lauderdale
N. B. Jordan, Quincy
T. T. Scott, Live Oak
J. T. Diamond, Secretary, Tallahassee
BRANCH STATIONS
NORTH FLORIDA STATION, QUINCY
J. D. Warner, M.S., Agron. Acting in
Charge
R. R. Kincaid, Ph.D., Asso. Plant Path.
Elliott Whiienurs, B.b.A., Asaisanii An.
Husbandman
Jesse Reeves, Asst. Agron., Tobacco
CITRUS STATION, LAKE ALFRED
A. F. Camp, Ph.D., Horticulturist in
Charge.
John H. Jefferies, Asst. in Cit. Breeding
B. R. Fudge, Ph.D., Associate Chemist
W L. T hompson, B.S., Associate
Entomologist
F. F. Cowart, Ph.D., Asso. Horticulturist
W. W. Lawless, E. S., Asst. Horticulturist
R. K. Voorhees, M.S., Asst. Plant Path.
EVERGLADES STA., BELLE GLADE
J. R. Neller, Ph.D., Biochemist in
Charge
J. W. Wilson, Sc.D., Entomologist
F. D. Stevens, B.S., Sugarcane Agron.
Thomas Bregger, Ph.D., Sugarcane
Physiologist
Frederick Boyd, Ph.D., Asst. Agronomist
G. R. Townsend, Pb.D., Plant Pathologist
R. W. Kidder, M.S., Asst. An. Husbandman
W. T. Forsee, Ph.D., Asso. Chemist
B S. Clayton, B.S.C.E., Drainage En-
gineer2
F. S. Andrews, Ph.D., Asso. Truck Hort.
SUB-TROPICAL STA., HOMESTEAD
W. M. Fifield, M.S., Horticulturist Act-
ing in Charge
S. J. Lynch, B.S.A., Asst. Horticulturist
Geo. D. Ruehle, Ph.D., Associate Plant
Pathologist
W. CENTRAL FLA. STA.,
BROOKSVILLE
W F. Ward, M.S., Asst. An. Husband-
man in Charges
FIELD STATIONS
Leesburg
M. N. Walker, Ph.D., Plant Pathologist
in Charge
K. W. Loucks, M.S., Assistant Plant
Pathologist
Plant City
A. N. Brooks, Ph.D., Plant Pathologist
Hastings
A. H. Eddins, Ph.D., Plant Pathologist.
E. N. McCubbin, Ph.D., Asso. Truck
Horticulturist
Monticello
Samuel O. Hill, B.S., Asst. Entomologist'
Bradenton
Jos. R. Beckenbach, Ph.D., Truck Horti-
culturist in Charge
David G. Kelbert, Asst. Plant Pathologist
Sanford
R. W. Ruprecht, Ph.D., Chemist in
Charge, Celery Investigations
W. B. Shippy, Ph.D., Asso. Plant Path.
Lakeland
E. S. Ellison, Meteorologist2
B. H. Moore, A.B., Asst. Meteorologists

iHead of Department
2In cooperation with U.S.
'Cooperative, other divisions, U. of F.







II. DRIED GRAPEFRUIT PULP FOR MILK PRODUCTION
P. T. Dix ARNOLD, R. B. BECKER AND W. M. NEAL
CONTENTS
PAGE PAGE
Historical .. ...... ... 3 Comi)arative Feeding Trials .... 9
Dried Grapefruit Pulp .. 6 Mineral Consumption During
Field Observations on Feeding Feeding Trials 11
Fresh Pulp 6 Effect of Dried Grapefruit Pulp on
Plan of Investigation 7.. .... Flavor of Milk .. .. 12
Experimental Results 7 Discussion of Results ... 12
Determination of Bulkiness 7 Summary and Conclusions 13
Palatability Trals .. 8 Literature Cited ....- ..... ----- 14
Dipestibility of Dried Grapefruit
Pulp and Dried Orange Pulp 8
Several kinds of citrus fruits are available for canning in
Florida, and incidentally for the utilization of the by-products
as dried citrus pulp. During the 1939-1940 season approximately
9,000,000 field boxes of grapefruit and 4,000,000 boxes of oranges
were used in Florida for canning purposes. In commercial prac-
tice no special efforts are made to produce pure dried grapefruit
or pure dried orange pulp. As a result mixed dried citrus pulp,
with grapefruit predominating, frequently is found on the
market.
About one-third of the total weight of grapefruit and oranges
entering a citrus cannery ultimately is used as human food. The
remaining portion of the fruit formerly was lost in processing,
or was disposed of as cannery waste at considerable expense.
The peel, rag, and seed provide a large potential source of feed
for cattle. By drying this material the citrus canning industry
has changed a liability into an asset, reducing the cost of disposal,
and converting the by-product into a non-perishable salable feed.
The present utilization of the material resulted in the Florida
production of 18,623 tons of dried citrus pulp during the 1939-
1940 season.
The process of converting the peel, rag, and seeds of citrus
fruits into dried citrus pulp has undergone a number of changes,
and may be further improved in the future.

HISTORICAL

The Florida Citrus Exchange established a research fellow-
ship with the Mellon Institute in October 1911 to investigate
possible utilization of citrus peel, rag, and seed as sources of com-
mercial by-products. F. Alex McDermott conducted the investiga-
tion and suggested (12)' that the pulp, seeds, and peel might have
considerable value as feed for livestock, although he did not in-
vestigate this issue.

'Italic figures in parentheses refer to "Literature Cited" in the back
of this bulletin.







II. DRIED GRAPEFRUIT PULP FOR MILK PRODUCTION
P. T. Dix ARNOLD, R. B. BECKER AND W. M. NEAL
CONTENTS
PAGE PAGE
Historical .. ...... ... 3 Comi)arative Feeding Trials .... 9
Dried Grapefruit Pulp .. 6 Mineral Consumption During
Field Observations on Feeding Feeding Trials 11
Fresh Pulp 6 Effect of Dried Grapefruit Pulp on
Plan of Investigation 7.. .... Flavor of Milk .. .. 12
Experimental Results 7 Discussion of Results ... 12
Determination of Bulkiness 7 Summary and Conclusions 13
Palatability Trals .. 8 Literature Cited ....- ..... ----- 14
Dipestibility of Dried Grapefruit
Pulp and Dried Orange Pulp 8
Several kinds of citrus fruits are available for canning in
Florida, and incidentally for the utilization of the by-products
as dried citrus pulp. During the 1939-1940 season approximately
9,000,000 field boxes of grapefruit and 4,000,000 boxes of oranges
were used in Florida for canning purposes. In commercial prac-
tice no special efforts are made to produce pure dried grapefruit
or pure dried orange pulp. As a result mixed dried citrus pulp,
with grapefruit predominating, frequently is found on the
market.
About one-third of the total weight of grapefruit and oranges
entering a citrus cannery ultimately is used as human food. The
remaining portion of the fruit formerly was lost in processing,
or was disposed of as cannery waste at considerable expense.
The peel, rag, and seed provide a large potential source of feed
for cattle. By drying this material the citrus canning industry
has changed a liability into an asset, reducing the cost of disposal,
and converting the by-product into a non-perishable salable feed.
The present utilization of the material resulted in the Florida
production of 18,623 tons of dried citrus pulp during the 1939-
1940 season.
The process of converting the peel, rag, and seeds of citrus
fruits into dried citrus pulp has undergone a number of changes,
and may be further improved in the future.

HISTORICAL

The Florida Citrus Exchange established a research fellow-
ship with the Mellon Institute in October 1911 to investigate
possible utilization of citrus peel, rag, and seed as sources of com-
mercial by-products. F. Alex McDermott conducted the investiga-
tion and suggested (12)' that the pulp, seeds, and peel might have
considerable value as feed for livestock, although he did not in-
vestigate this issue.

'Italic figures in parentheses refer to "Literature Cited" in the back
of this bulletin.






Florida Agricultural Experiment Station


A small quantity of grapefruit cannery by-product was dried
experimentally by Seth S. Walker (11) in March 1925, in the
laboratory of the Florida Citrus Exchange. The unground peel,
rag, and seed were spread on hardware cloth trays and dried
over steam coils until brittle, then ground in a mill with one-half
inch plates. Most of the seeds were crushed. This coarsely ground
material, containing 18 percent of moisture, was fed, in addition
to the regular rations, to six Jersey cows at the Florida Agricul-
tural Experiment Station by John M. Scott (10). An increase in
milk yield resulted, from which he concluded that the product
had merit as a feed but that further work was necessary for its
evaluation.
Dried grapefruit pulp was placed on the Florida market in
commercial quantities in 1932.
Dairymen near an orange by-products factory in California
fed some fresh orange pulp as early as 1922, apparently with
good results (9). Dried orange pulp was fed in 1926 with cut


Fig. 2.-Raw Citrus pulp being dumped at a Florida plant for drying into feed.







Citrus By-Products


alfalfa hay to five wethers at the California station (5). It yielded
6.0 percent of digestible crude protein and 78.3 percent of total
digestible nutrients. Dried lemon pulp fed similarly yielded 3.0
percent of digestible crude protein and 72.8 percent of total diges-
ible nutrients (6).
As much as 8 pounds of dried orange pulp mixed with wheat
bran were consumed daily by dairy cows at the California station
(9). Used in a feeding trial, no difference was detected in the
milk production of cows while their rations contained dried beet
pulp or dried orange pulp.
Digestion trials conducted in 1934 at the Florida station,
using four steers, showed dried grapefruit pulp to yield 1.2
percent of digestible crude protein and 76 percent of total digest-
ible nutrients, whereas dried orange pulp yielded 2.1 percent of
digestible crude protein and 69.6 percent of total digestible nu-
trients (8). The dried pulps used in California and in Florida
were prepared by different methods.
Dried citrus pulp and dried beet pulp were compared during
1938 in a single feeding trial with 38 Holstein cows at the Belcher-























Fig. 3.-Loading citrus dairy feed at a Florida plant. In the 1939-40
season 18,623 tons of dried citrus pulp for feed was produced.






Florida Agricultural Experiment Station


town State School in Massachusetts. Archibald (1) concluded
from the results of this trial that citrus pulp could replace dried
beet pulp.
Garrett and associates (4) fed dried grapefruit pulp in 1939
to 12 cows immediately after milking. A bitter flavor varying
in intensity was observed at times in the milk of five cows, which
was attributed to the feed.

DRIED GRAPEFRUIT PULP
The dried grapefruit pulp used in most of the present investi-
gations was the product originally on the market in 1932. The
pulp was dried commercially using grapefruit rag, seed, and
peel direct from a cannery. This material was passed between
large corrugated rollers which cut the peel into narrow strips,
crushed the seeds, and squeezed out much of the "free" water.
This rolled material was conveyed into a large drier, where
it was subjected to direct heat from an oil-burning furnace, and
reduced to about 4 percent moisture. When bagged and stored in
a warehouse the grapefruit pulp absorbed water from the atmos-
phere until it attained a moisture content of 10 to 12 percent.
The process of manufacture was changed prior to the second
and third comparative feeding trials. The product used in those
trials was prepared by adding a small amount of a calcium com-
pound to the macerated pulp. This set free a part of the "bound"
water (water of constitution), and allowed more water to be
removed mechanically from the peel. Some soluble material was
removed with the water. With a shorter drying period, less fuel
was required than with the earlier process. This dried citrus
pulp had a light grayish color and a pleasant aroma.
FIELD OBSERVATIONS ON FEEDING FRESH PULP

Since the first dried grapefruit pulp was fed in Florida a
considerable number of dairymen have obtained the fresh citrus
pulp in quantity at local canneries and fed it to dry dairy cows
and heifers. Many dairymen have fed some fresh pulp to cows in
milk, a few of whom observed that a slight flavor could be
imparted to the milk, especially by citrus other than grapefruit,
when fed shortly before milking time. The supply of fresh pulp
is interrupted at times due to part-time operation of the canneries
at some seasons. For obvious reasons fermenting pulp should
not be fed. Some fresh grapefruit pulp has been ensiled by one







Citrus By-Products


cattleman, who mixed it with dry grass. A fair quality of silage
resulted but the cattle showed a definite preference for the
ensiled rag and seed, rather than the peel.

PLAN OF INVESTIGATION
The investigation of dried citrus pulp involved the determin-
ation of the palatability, digestibility, effects upon the animals
and their products, and the relative value of this feed as com-
pared with a widely accepted standard product-dried beet pulp.
A palatability trial using dried grapefruit pulp was con-
ducted with Jersey cows in the Experiment Station herd. The
digestibilities of dried grapefruit pulp and dried orange pulp were
determined, using four steers, as reported previously (8).
The effects of dried grapefruit pulp upon the cows and upon
the flavor of the milk were observed during the course of the
feeding trials. The comparative feeding value of the dried grape-
fruit pulp and dried beet pulp were determined in standard
double-reversal feeding trials (2) in each of three consecutive
winters.
In each trial eight Jersey cows were grouped into two lots
as nearly equal as possible in body weights, milk yields, and
stages of lactation. Rations were calculated according to the Mor-
rison standard (7) at the beginning of each 30-day period. Rough-
ages in the basal ration consisted of alfalfa hay and corn silage,
supplemented by corn feed meal and cottonseed meal (41 percent
total crude protein). Water, common salt, and finely ground
feeding bonemeal were supplied in dry lot, where the cows
remained except during the milking hours. The cows were
weighed at the usual intervals, as mentioned later. All feed,
refused feed, and milk were weighed twice daily. Feeds were
sampled for chemical analysis and the butterfat content of the
milk was determined from individual five-day composite samples
obtained in the middle of each experimental period. All data
were calculated according to the standard methods (2) for this
type of feeding trial.
EXPERIMENTAL RESULTS
DETERMINATION OF BULKINESS
Dried grapefruit pulp is a bulky concentrate feed. The
weight per quart was found to vary with the methods of process-
ing the material, and the fineness of the dried product. When







Citrus By-Products


cattleman, who mixed it with dry grass. A fair quality of silage
resulted but the cattle showed a definite preference for the
ensiled rag and seed, rather than the peel.

PLAN OF INVESTIGATION
The investigation of dried citrus pulp involved the determin-
ation of the palatability, digestibility, effects upon the animals
and their products, and the relative value of this feed as com-
pared with a widely accepted standard product-dried beet pulp.
A palatability trial using dried grapefruit pulp was con-
ducted with Jersey cows in the Experiment Station herd. The
digestibilities of dried grapefruit pulp and dried orange pulp were
determined, using four steers, as reported previously (8).
The effects of dried grapefruit pulp upon the cows and upon
the flavor of the milk were observed during the course of the
feeding trials. The comparative feeding value of the dried grape-
fruit pulp and dried beet pulp were determined in standard
double-reversal feeding trials (2) in each of three consecutive
winters.
In each trial eight Jersey cows were grouped into two lots
as nearly equal as possible in body weights, milk yields, and
stages of lactation. Rations were calculated according to the Mor-
rison standard (7) at the beginning of each 30-day period. Rough-
ages in the basal ration consisted of alfalfa hay and corn silage,
supplemented by corn feed meal and cottonseed meal (41 percent
total crude protein). Water, common salt, and finely ground
feeding bonemeal were supplied in dry lot, where the cows
remained except during the milking hours. The cows were
weighed at the usual intervals, as mentioned later. All feed,
refused feed, and milk were weighed twice daily. Feeds were
sampled for chemical analysis and the butterfat content of the
milk was determined from individual five-day composite samples
obtained in the middle of each experimental period. All data
were calculated according to the standard methods (2) for this
type of feeding trial.
EXPERIMENTAL RESULTS
DETERMINATION OF BULKINESS
Dried grapefruit pulp is a bulky concentrate feed. The
weight per quart was found to vary with the methods of process-
ing the material, and the fineness of the dried product. When






Florida Agricultural Experiment Station


poured slowly into a large square box (1,365 cubic inches) with-
out causing it to settle, densities were found to range between
.57 and .80 pounds per measured quart. The average density,
based on 45 determinations with pulp from four sources, was .71
pounds per quart. Dried grapefruit meal, which was passed
through a hammer mill, had an average density of .97 pounds
per quart, based on 14 determinations. These densities compare
with .6 pounds per quart for such feeds as dried beet pulp, dried
brewer's grains and alfalfa meal, 1.1 pounds per quart for old
process linseed oil meal, 1.5 pounds for cottonseed meal, and
1.5 to 2.0 pounds for several farm grains.
The weight per quart of dried grapefruit pulp is not a full
measure of its bulkiness as a feed: This product swells consider-
ably upon contact with water or the digestive juices. This char-
acteristic adapts the dried citrus pulp as a partial substitute for
roughage in regions of roughage scarcity.
PALATABILITY TRIALS
Dried grapefruit pulp was tested for its palatability with
dairy cows that had not received this feed previously. After con-
suming their regular allowance of mixed concentrates at the
afternoon milking, one pound of dried grapefruit pulp was placed
in the manger in front of each of 31 Jersey cows. Fourteen of
these cows ate part of the offering the first afternoon. This pro-
cedure was repeated on each of six consecutive days, at the end
of which time 24 of the cows consumed the entire offering, and
only five of the 31 animals refused to eat the grapefruit pulp
after their regular allowance of mixed concentrates had been
consumed. Only one of the animals refused to eat a least a part
of the grapefruit pulp on all six occasions, when offered separately
in this manner. This method is believed to be a test of the absolute
palatability of this new product. It appeared to have no particu-
larly objectionable flavor, since the proportion eaten by the
cows increased progressively in nearly all instances.
DIGESTIBILITY OF DRIED GRAPEFRUIT PULP AND
DRIED ORANGE PULP
To measure the feeding value of dried grapefruit and orange
pulps, separate digestion trials were conducted (8). Dried grape-
fruit pulp was used to replace part of the cut alfalfa hay in a
ration of alfalfa hay and cottonseed meal with four steers. The
trial covered a period of 30 days, during the last 20 days of which






Citrus By-Products


the feed and feces were analysed, and the digestibility of the feed
determined. The steers digested 24.8 percent of the crude protein,
71.5 percent of the crude fiber, 92.4 percent of the nitrogen-free
extract, and 79.4 percent of the crude fat. It was calculated that
dried grapefruit pulp used in this trial yielded 1.2 percent diges-
tible crude protein and 76.0 percent total digestible nutrients'.
A similar trial with dried orange pulp showed it to be only
slightly less valuable than the dried grapefruit pulp when con-
sidered on the dry matter basis.2
COMPARATIVE FEEDING TRIALS
Three comparative feeding trials were conducted with Jersey
cows in the Experiment Station dairy herd during the winter
months in the years 1936 to 1939. The dried grapefruit pulp was
compared with dried beet pulp, which is the nearest similar feed
used commonly in dairy rations. These two feeds were fed dry
in alternate 30-day periods, in amounts to provide 40 percent of
the total digestible nutrient requirements of the cows. The basal
ration consisted of two-thirds of the usual allowance of good
quality corn silage and of No. 1 (Federal grade) green alfalfa hay.
Supplementary concentrates consisted of equal parts of corn
feed meal and cottonseed meal (41 percent total crude protein),
in amounts to balance the ration in total digestible nutrients and
to furnish a slight excess of digestible protein. The experimental
cows were confined in a dry lot where they had access to finely
ground feeding bonemeal, common salt, and water.
The cows were divided into two lots of four animals each,
as nearly equal as possible according to body weight, stages of
lactation and gestation, and average milk production. They were
weighed on three consecutive days at the beginning and end of
each experimental period. Consumption of feed and mineral
matter, and milk production, were recorded.
Each feeding trial was of 90 days' duration, consisting of
three consecutive 30-day periods. The first 10 days of each period
were regarded as preliminary, allowing feed in the alimentary
tract to be replaced by the experimental ration. Records for the
last 20 days of each period were used in calculations to indicate
the value of the dried grapefruit and beet pulps.
The feed consumption and milk production, calculated ac-
cording to the usual methods, are presented in Table 1.

2Refer to Fla. Agr. Exp. Station Bul. 275 for more details.







Florida Agricultural Experiment Station


TABLE 1.-FEED CONSUMPTION, MILK AND BUTTERFAT YIELDS, AND CHANGES IN
BODY WEIGHT OF COws DURING THE 20-DAY EXPERIMENTAL PERIODS OF THE
FEEDING RIALSS COMPARING DRIED GRAPEFRUIT PULP WITH DRIED BEET PULP*.
Corn Alfalfa Dried Concen- Butter- Changes
Year Silage Hay Pulp trates Milk fat in Wgt.
pounds pounds pounds pounds pounds pounds pounds
Dried Grapefruit Pulp Periods
1936-1937 2,688.4 835.0 1,047.0 430.1 2,298.4 119.60 -13.0
1937-1938 2,734.4 913.8 979.6 427.7 2,406.1 124.32 -21.5
1938-1939 2,877.5 958.5 1,325.0 709.5 3,209.9 176.58 60.0
Dried Beet Pulp Periods
1936-1937 2,732.6 876.5 1,134.9 464.4 2,248.7 114.46 139.5
1937-1938 2,758.9 922.1 1,138.9 419.3 2,380.2 117.46 86.5
1938-1939 2,874.0 958.5 1,370.4 645.0 3,092.4 170.63 90.0
*Feed consumption and milk production while the cows received
dried grapefruit pulp during the first and third 20-day experimental
periods were averaged, and added to those of the other group of cows
while receiving the same feed during the second 20-day experimental
period.
The same calculation was made with regard to the records while
the cows received dried beet pulp. This is the application of the usual
formula:
Ia + IIIa = Ib + IIIb
+ IIa +IIb
2 2
when "a" represents the first, and "b" the second experimental ration.
Amounts of feeds consumed were computed on the basis of
each 100 pounds of milk produced in the feeding trials comparing
dried grapefruit pulp with dried beet pulp. The results of these
computations are given in Table 2.

TABLE 2.-FEED CONSUMPTION AND CHANGES IN BODY WEIGHT PER 100 POUNDS
OF MILK PRODUCED DURING THE FEEDING TRIALS COMPARING DRIED GRAPEFRUIT
PULP WITH DRIED BEET PULP.

Corn Alfalfa Dried Concen- Changes Butter-
Year Silage T-av Pulp trates in Wgt. Milk fat
pounds pounds pounds pounds pounds pounds pounds

Dried Grapefruit Pulp Periods
1936-1937 117.0 36.3 45.6 18.7 -0.6 100 5.2
1937-1938 113.7 38.0 40.7 17.8 -0.9 100 5.2
1938-1939 89.6 29.9 41.3 22.1 1.9 100 5.5
Dried Beet Pulp Periods
1936-1937 121.5 39.0 50.5 20.7 6.2 100 5.1
1937-1938 115.9 38.7 47.9 17.6 3.6 100 4.9
1938-1939 92.9 31.0 44.3 20.9 2.9 100 5.5
Averages
Grapefruit 106.8 34.7 42.5 19.5 0.1 100 5.3
Beet pulp 110.1 36.2 47.6 19.7 4.3 100 5.2






Citrus By-Products


Composition of the dried grapefruit pulp used in these feed-
ing trials, calculated on the dry matter basis, is shown in Table 3.
The variety of the grapefruit and proportion of seeds in the dried
pulp will affect its composition slightly.
TABLE 3.-COMPOSITIoN OF THE DRIED GRAPEFRUIT PULP USED IN THE COMPARATIVE
FEEDING TRIALS.
On Dry Matter Basis





C) ) a I)C)
PH u 0 4a Ufi Ja UPg P; M
1936-1937 12.0 6.0 5.0 11.1 58.1 2.32 .16 .12
1937-1938 10.5 6.8 7.4 12.0 54.2 3.13 .12 .13
1938-1939 11.5 6.4 4.2 13.1 58.4 1.57 .09 .11
Average 11.3 6.4 5.5 12.1 56.9 2.34 .12 .12
The Jersey cows used in these comparative feeding trials
produced slightly more milk while consuming the rations con-
taining dried grapefruit pulp, but consumed slightly more feed
and gained more in body weight during the periods when dried
beet pulp was a part of the rations. By calculating the digestible
nutrients provided by each feed, according to its chemical com-
position and average coefficients of digestibility, it was found
that irrespective of changes in body weight, 42.5 pounds of dried
grapefruit pulp were equivalent approximately to 45.1 pounds of
dried beet pulp. The difference is so slight that these feeds are
considered practically equal in feeding value when used as a
source of digestible carbohydrates.
The cows remained in good physical condition throughout
all of these feeding trials. Their hair was sleek and glossy. Not a
single record was lost because of a cow going off-feed.
MINERAL CONSUMPTION DURING FEEDING TRIALS
Common salt and finely ground feeding bonemeal were
accessible in separate compartments of a mineral box during each
of the 90-day feedings trials. Neither salt nor bonemeal was
included in the concentrates, although these cows had been
receiving feed previous to each trial that contained 1 percent of
common salt and 2 percent of either finely ground feeding bone-
meal or a mixture consisting of equal parts of bonemeal and
finely ground marble dust (calcium carbonate). Consumption of
salt and bonemeal is given in Table 4.






Florida Agricultural Experiment Station


TABLE 4.-CONSUMPTION or SALT AND BONNEIEAL BY JERSEY COWS DURING THE
DOUBLE-REVERSAL FEEDING TRIALS.
Year Number of Cows Common Salt Bonemeal
pounds pounds
1936-1937 8 99.7 20.5
1937-1938 8 80.1 22.7
1938-1939 8 51.3 9.7
Average per cow per month 3.21 0.72
EFFECT OF DRIED GRAPEFRUIT PULP ON FLAVOR OF MILK
Samples of milk from individual cows in the feeding trials
were submitted to Dr. L. M. Thurston of the Dairy Products
Laboratory. He found that no flavor characteristic of either dried
grapefruit pulp or of dried beet pulp was passed into the milk
by the cows while receiving these feeds. It is to be noted that
both of these feeds were given to the cows in the dry form, as is
the recommended practice. Some dairymen have stated that when
dried grapefruit pulp was soaked, it imparted a noticeable flavor
when fed in quite large amounts shortly before the cows were
milked.
DISCUSSION OF RESULTS
A fair comparison of two feeds can be obtained only when
they constitute a large part of the total ration. To incorporate
such bulky feeds as grapefruit pulp and beet pulp, and supply as
much as 40 percent of the total digestible nutrients required in
dairy rations, it was found desirable to reduce the roughage
allowance to two-thirds of the amounts usually recommended.
Grapefruit pulp swells greatly because of the water-holding
property of one of its constituents, namely, pectin. Under these
conditions a practical concentrate mixture for balancing the
protein and total digestible nutrients was made by adding two
concentrate feeds. Corn feed meal and cottonseed meal (41 per-
cent total crude protein) were selected because of their low cost
and ready availability.
Since the canneries in Florida process more grapefruit than
other citrus fruit, the dried grapefruit pulp was used throughout
this investigation, except in one series of digestion trials.
No attempt was made to soak dried grapefruit pulp. The
dairy cows, heifers, and the steers used in the digestion trials
found grapefruit pulp to be palatable. It was more convenient,
sanitary, and required less labor to feed the pulp in the dry
form.
Within the limits of variations between lots of animals, and
the ability to measure slight differences in feeds quite similar







Citrus By-Products


in composition, the milk and butterfat production of Jersey cows
in these trials was practically equal. Slightly increased milk
yields while the cows received the grapefruit pulp ration were
offset by increased consumption of feed and corresponding body
gains during the periods on beet pulp. These differences were
within the limits of error in working with biological materials.
Based on chemical composition, total digestible nutrients and
results obtained in the comparative feeding trials, dried grapefruit
pulp is considered to be the equal of dried beet pulp in rations
for milk production.
SUMMARY AND CONCLUSIONS
Dried grapefruit pulp was palatable to dairy cows, even
after they had received their full regular feed.
Dried grapefruit pulp is a bulky feed, the weight varying
according to the process of manufacture. The average density
of dried grapefruit pulp was .71 pounds per quart, and of dried
grapefruit meal .97 pounds.
Dried grapefruit pulp, used in these trials, yielded 1.2 per-
cent of digestible crude protein and 76.0 percent of total digesti-
ble nutrients. The proportion of seeds contained and the variety
of grapefruit would affect the composition and digestible nutri-
ents slightly.
Slightly more milk and butterfat were produced while the
cows received dried grapefruit pulp, but feed consumption and
body weights were slightly greater during the periods on dried
beet pulp. Results indicate that these two by-products are prac-
tically equal in feeding value when supplied as bulky carbohy-
drate feeds to dairy cows.
No flavor characteristic of either dried grapefruit pulp or
dried beet pulp was noted in the milk obtained during these
feeding trials.
Dried citrus pulp is a desirable bulky carbohydrate concen-
trate for use in the rations of dairy cattle.
ACKNOWLEDGEMENTS
During these feeding trials the students employed with the dairy
herd aided with the care of the cows and in keeping experimental
records of the milk and feeds. These men included Sidney P. Marshall
M. L. Bishop, and Kenneth A. Clark. Feed samples were analysed in the
Nutrition Laboratory with the help of L. L. Rusoff and I. I. Rusoff. Dr.
L. M. Thurston conducted the tests on the flavor of the milk.
Part of the dried grapefruit and dried orange pulps used in the
earlier phases of investigation were supplied by R. B. Webster, of Jack-
sonville, Florida.
Pictures for Figs. 2 and 3 from Florida Agricultural Extension Ser-
vice.







Citrus By-Products


in composition, the milk and butterfat production of Jersey cows
in these trials was practically equal. Slightly increased milk
yields while the cows received the grapefruit pulp ration were
offset by increased consumption of feed and corresponding body
gains during the periods on beet pulp. These differences were
within the limits of error in working with biological materials.
Based on chemical composition, total digestible nutrients and
results obtained in the comparative feeding trials, dried grapefruit
pulp is considered to be the equal of dried beet pulp in rations
for milk production.
SUMMARY AND CONCLUSIONS
Dried grapefruit pulp was palatable to dairy cows, even
after they had received their full regular feed.
Dried grapefruit pulp is a bulky feed, the weight varying
according to the process of manufacture. The average density
of dried grapefruit pulp was .71 pounds per quart, and of dried
grapefruit meal .97 pounds.
Dried grapefruit pulp, used in these trials, yielded 1.2 per-
cent of digestible crude protein and 76.0 percent of total digesti-
ble nutrients. The proportion of seeds contained and the variety
of grapefruit would affect the composition and digestible nutri-
ents slightly.
Slightly more milk and butterfat were produced while the
cows received dried grapefruit pulp, but feed consumption and
body weights were slightly greater during the periods on dried
beet pulp. Results indicate that these two by-products are prac-
tically equal in feeding value when supplied as bulky carbohy-
drate feeds to dairy cows.
No flavor characteristic of either dried grapefruit pulp or
dried beet pulp was noted in the milk obtained during these
feeding trials.
Dried citrus pulp is a desirable bulky carbohydrate concen-
trate for use in the rations of dairy cattle.
ACKNOWLEDGEMENTS
During these feeding trials the students employed with the dairy
herd aided with the care of the cows and in keeping experimental
records of the milk and feeds. These men included Sidney P. Marshall
M. L. Bishop, and Kenneth A. Clark. Feed samples were analysed in the
Nutrition Laboratory with the help of L. L. Rusoff and I. I. Rusoff. Dr.
L. M. Thurston conducted the tests on the flavor of the milk.
Part of the dried grapefruit and dried orange pulps used in the
earlier phases of investigation were supplied by R. B. Webster, of Jack-
sonville, Florida.
Pictures for Figs. 2 and 3 from Florida Agricultural Extension Ser-
vice.







Florida Agricultural Experiment Station


LITERATURE CITED
1. Archibald, J. G. Dried citrus pulp. The New England Homestead,
March 11, 1939.
2. Forbes, E. B., and H. S. Grindley. On the formulation of methods
of experimentation in animal production. Bul. Nat'l Res. Council,
Vol. 6 Part 2, No. 32: 3-16. 1923.
3. Futch. M. C., L. L. Rusoff, and R. B. Becker. The vitamin A content
of dried citrus pulp. Jour. Dairy Sci. 22: 115-116. 1939.
4. Garrctt, O. F., R. B. Arnold, and G. H. Hartman. A comparison of
the effects of seven different types of roughages on the color and
flavor of milk. Jour. Dairy Sci. 23: 497-498. 1940.
5. Mead, S. W., and H. R. Guilbert. The digestibility of certain fruit
by-products as determined for ruminants. Part I. Dried orange
pulp and raisin pulp. Calif. Agr. Expt. Sta. Bul. 409: 3-11. 1926.
6. Mead, S. W., and H. R. Guilbert. The digestibility of certain fruit
by-products as determined for ruminants. Part II. Dried pineapple
pulp, dried lemon pulp, and dried olive pulp. Calif. Agri. Expt.
Sta. Bul. 439: 3-11. 1927.
7. Morrison, F. B. Feeds and Feeding, 20th edit. The Morrison Publ.
Co. Pages 1001 and 1004. 1936.
8. Neal, W. M., R. B. Becker, and P. T. Dix 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. Expt. Sta. Bul. 275: 3-26. 1935.
9. Regan, W. M., and S. W. Mead. The value of orange pulp for milk
production. Calif. Agr. Expt. Sta. Bul. 427: 3-16. 1927.
10. Scott, J. M. Grapefruit refuse as a dairy feed. Fla. Agr. Expt. Sta.
Ann. Rpt. 1926: 25R-26R. 1926.
11. Walker, S. S. Correspondence of July 30, 1925, to J. M. Scott.
12. Walker. S. S., and F. A. McDermott. The utilization of cull citrus
fruits in Florida. Fla. Agr. Expt. Sta. Bul. 135: 130-144. 1917.




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