Experiments on the digestibility of prickly pear by cattle

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Title:
Experiments on the digestibility of prickly pear by cattle
Series Title:
Bulletin / United States. Dept. of Agriculture. Bureau of Animal Industry ;
Physical Description:
38 p., 1 leaf of plates : ill. ; 23 cm.
Language:
English
Creator:
Hare, R. F ( Raleigh Frederick ), b. 1870
Publisher:
U.S. Dept. of Agriculture, Bureau of Animal Industry
Place of Publication:
Washington, D.C
Publication Date:

Subjects

Subjects / Keywords:
Prickly pears   ( lcsh )
Cattle -- Feeding and feeds   ( lcsh )
Genre:
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

Statement of Responsibility:
by R.F. Hare.
General Note:
"May 28, 1908."

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 029613612
oclc - 22301933
System ID:
AA00018910:00001

Full Text







.. ,. R :: .UREAU'QF ANIMAL INDUSTRY.-BULLETIN 106.
; ': ", -A ., 0. MELVIN, CHIEF 0f ,UREAU.
..... ...





..ENTS ON THE DIGESTIBILITY OF


..pk PRICKLY PEAR BY CATTLE.
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i^l^R" ''. ,ENTS' O -TH DIGESTIILITYO








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Issued May 28, 1i8.

U. S. DEPARTMENT OF AGRICULTURE,
BUREAU OF ANIMAL. INDUSTRY.-BULLETIN 106.
TI) MI- I VIN, CIEF OF BUREAU.





EXPERIMENTS ON THE DIGESTIBILITY OF

PRICKLY PEAR BY CATTLE.





BY

R. F. HARE,
Profe'ssor of CliJmis/h rI in tl.'r" Coiihi',"t of A,,riciil i/re and .l)/li/.1/t"
.-i Is of the, 7i'ritory of New .1 r ico.


WASHINGTON:
GOVERNMENT PRINTING OFFICE.
1908.















































Ligiozed Dy he iI-m.rilei Archiwe
in 2012 jII I lhOIuCI.,II OlOn
University of Florida, George A. Sinmaihers Libr iri- 'Ir, SuLJpporl irom L'RASIS a'd he SIoan FoLndalion


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LETTER OF TRANSMITTAL.


U. S. DEPARTMENT OF AGRICULTURE,
BUREAU OF ANIMAL INDUSTRY,
t'l..li7i;gtnl, D. C., March 13, 1908.
Si it: I have the honor to transmit herewith and to recommend for
publication as Bulletin 106 of this Bureau a manuscript entitled
"Experiments on the Digestibility of -Prickly Pear by Cattle," by
R. F. IIare, Professor of Chemistry in the College of Agriculture and
Mechanic. Arts of the Territory of New Mexico.
While the experiments reported in this paper were conducted by
Professor Hare in cooperation with the Bureau of Plant Industry, it
has beeri thought advisable to publish the paper as a bulletin of the
BuLreau of Animal Industry, inasmuch as it deals primarily with the
animal side of the subject.
Very respectfully, A. D. MELVIN,
Chief of Bureau.
Hon. JAMES WII.SON,
Secretary of Agi i'ulfuri'.
















LETTER OF SUBMITTAL.


U. S. DEPARTMENT OF AGRICULTURE,
BUREAU OF PLANT INDUSTRY,
l\u.shitgtui, D. C., February 1. 1,908.
SIR: I have the honor to transmit herewith and to recommend for
publication as a bulletin of the Bureau of Animal Industry thle accom-
panying manuscript entitled "Experiments on the Digestibility of
Prickly Pear by Cattle."
This paper was prepared by Prof. R. F. Hare, chemist, College of
Agriculture and Mechanic Arts of the Territory of New Mexico, under
cooperative arraingemeniits with this Bureau, and was submitted for
the purpose of publication by Prof. W. J. Spillmnan, in charge of Farm
Manngenient Invcst'ii.. atiuns.
In previous bulletins of the Bureau of Plant Industry and the Agri-
cultural Experiment Station of New Mexico much information has
been published upon the.practical use and the chemical composition
of a large number of prickly pears and other cacti. The value of a
feed, however, is not determined by the chemical composition alone;
it is also necessary to know the percentage of digestibility of the nutri-
ents found by the chemist. This information is s-upplied in the
accompanying manuscript.
Respectfully, B. T. GALLOWAY,
Utif' ol Bureau.
Dr. A. D. MELVIN,
Chief, Bureau of I n i i a I Industry.




















CONTENTS.

Page
Introduction ............................. .............. .................... 7
Met hod ,f conducting digestion experiments...------------------------------...................... 7
Definition of some technical terms and discussion of the functions of foods .... 8
"'iiipsi w i , f feeding stuffs ................................ .......... 9
Fu nv't i n of the nutrients ....... .........-------- . .............. ......... 11
Method of determining the di .Eesl iblW nutrients of prickly pear from the com-
position and il ig,,t iin coefficient.---....-------...-.- -------..............- 11i
Preparation of standard rations ............................................. ---------------12
Plan of the experiments--------- .................................................... 14
The animals used......--------------......--....- --- -.. --------------- ... ............. 14
The different rations used ............................................... --- 15
Description of the stalls .................... ........... .............. 15
Tie fveiling .................................... .................--- .-... -------- ------- 16
Collecting the feces ............................ ....................... 17
S',Jllectingi the urine----- .........-------- ...................... ..............------------------ 17
Preparation of the samples .............................................. --------------------------18
Repi rt of the experiments------------------------ ................................................ 18
Exp-riment No. 1. Digestibility of prickly pear (Opiintia lindheimeri)... 18
Experiment Ni, 2. Di ti ihility. of prickly pear (Opuntia v'is?) ..---......--. 21
Experiment No. 3. Dig>-til1ilil,. of prickly pear (Opuntia . g,,io;
Sy1, li,,h'.. and( alfalfa- ........................ .. .........--------........ -------------- --- 23
Experiment No. 4. Dig-'ilility of prickly pear (Opuntia i",,ii.i,,i
cycloides) and cotton-seed meal ....................................... 25
Experin-nt X.. 5. Digestibility of a fair quality of second-cut alfalfa..... 29
Effe. t of prickly pear on the di-ililii -y of other feeding -*tnf-;f .. ........ 31
Income and outgo of nitrogen .......................................... 35
Conclusions ..........-- ............. .... .... ------------ ..-.-.. ........... ....... 37































ILLUSTRATIONS.


PLATE.


PLATE I. Fig. 1.-Opunlia lindheimeri. Two-year-old .-c,,nd growth of -'pecies
fed in the first experiment. Fig. 2.-Opuntia ,ufgflorfil'ii i1-
cloides. Old plants of species fed in the third experiment........

TEXT FIGURE.

FIG. 1. The stalls used in'experiments Nos. 2 to 5 --.....-...--................


Pege.


8








EXPERIMENTS ON THE DIGESTIBILITY OF PRICKLY
PEAR BY CATTLE.


INTRODUCTION.
Many chemical analyses have been made of a number of different
members of the cactus family to determine their value as a feeding
stuff for animals.a With this data we are enabled to judge with a
fair degree of accuracy the amount of the various nutrients con-
tained by many different species of this group of plants, as well as by
different parts of the same plant. However, as no record of diges-
tion experiments with any of the cacti has been founil, it was impos-
sible to say what proportion of the different nutrients were available
to the animals. Tihe increased use of the prickly-pear (the flat-
jointedl members of the genus Opuntia) as a feed for all classes of
ruminants, especially for range and dairy cattle, makes it important
for the proper preparation of a ration that the feeder know how much
digestible nutrients to expect from feeding a given quantity of the
plant either alone or mixed with other feeding stuffs. The following
experiments have therefore been conducted to determine the digesti-
bility of prickly pear and thus guide the feeder in the preparation of
rations from this plant.
The investigations have been conducted in cooperation with the
Office of Farm Management Investigations, Bureau of Plant Industry,
United States Department of Agriculture. The author acknowl-
edges the assistance of Dr. David Griffiths, of that Office, who has
spared neither time nor pains in an effort to make the experiments
successful. Acknowledgment is made of the careful and painstaking
analytical chemical work of Messrs. S. R. Mitchell and R. B. Deemer.
METHOD OF CONDUCTING DIGESTION EXPERIMENTS.
The principle of conducting a digestion experiment is very simple.
First, the animal is fed on the feedii.g stuff the digestibility of which
is to be determined until all other feeds have been removed from the
alimentary canal, when the animal is said to be in a condition of equi-
librium with this feed. The animal is then placed in a stall specially
designed for feeding and for collecting refuse and excreta without
waste. It is then fed a weighed amount of the feeding stuff, the com-
position of which is determined by analysis. All the refuse is col-
lected, weighed, analyzed, and the amount of the several nutrients
a See Bulletin 60 of the New Mexico Experiment Station.






DIGESTIBILITY OF PRICKLY PEAR BY CATTLE.


which it is found to contain is subtracted from the amount of the''
corresp.oiling nutrients fed. As nearly as possible that portion of :
the feces which corresponds to the weighed feed eaten is carefully
collected, weighed, and analyzed. The amount of the different
nutrients found in the feces subtracted from the amount eaten gives
the amount of each nutrient digested. This result, multiplied by 100
and divided by the amount eaten, gives the percentage of digestible
nutrients, which is called the "coefficient of digestibility."

DEFINITION OF SOME TECHNICAL TERMS AND DISCUSSION OF
THE FUNCTIONS OF FOODS.

Most of the readers of these pages will doubtless be familiar with
the technical terms that are used throughout this bulletin and under-
stand how the value of a feeding -,tuff is determined from its analysis
and from the digestion coefficient of the several nutrients, but it may
not be amiiss briefly tot, define and discuss them here for the benefit
of thle few who may not be thoroughly familiar with them. For this
reason there are given below definitions of some of the terms used,
with the names of the constituents that are usually determined in
fixing thle value of a feeding stuff, and a brief discussion of the func-
tions of each in the animal body.
It should be remembered that in the feeding of animals the amount
of nourishment obtained from any feed by an animal does not alto-
gether depend upon the weight if the feed taken into the body.
Green matter, for instance, with 60 to 9.5 per cent of water will not,
of course, furnish as much substance as will cured fodders and grains.
The scientific feeder must. not only prepare the rations for his animals
on the basis of the amount of dqlry matter present, but it is also neces-
sary that lie should know how much nourishment a given amount of
this dry matter can furnish them. The dry matter of the different
feeds hlias been found to vary greatly in the amount of nutrients which
it contains as well as in its digestibility. A feed which has been
adulterated with cotton-seed hulls, chaff, sawdust, or other fibrous
and insoluble or difficultlv soluble matter would not, for instance,
be as digestible, and consequently could not furnish as much nourish-
ment pound for pounds, as some feed in which the nutrients were in a
form more readily available to the animal. It is, therefore, not only
necessary that the amount of dry matter in a feed be known, but it is
equally important to know the character and composition of this dry
matter.
The animal body is made up of water, mineral matter (or ash),
nitrogenous matter (or proteids), and fat. The function of the feed
which animals eat is to maintain the supply of this material so that
they may grow, perform work, and maintain a healthy condition.







BUL. 106, BUREAU OF ANIMAL INDUSTRY, U. S. DEPT. OF AGRICULTURE.


FIG. 1.-OPUNTIA LINDHEIMERI. TWO-YEAR-OLD SECOND GROWTH OF SPECIES FED IN
THE FIRST EXPERIMENT.


FIG. 2.-OPUNTIA ENGELMANNII CYCLOIDES. OLD PLANTS OF SPECIES FED IN THE THIRD
EXPERIMENT.


PLATE I.








DEFINITION OF TECHNICAI. TERMS.


It is a well-establislhetl fact that all feil., have certain .grorips of
substances that. perform dieir peculiar functi,,ns in building the dif-
ferent parts of the animal ibod y, and the object f a ichemnical analysis
of any feeding stuff is to separate and determine these gr'mips. They
are usually separated into the following: Water, ash, cther extract,
crude fiber, protein, nitrtogen-free extract, and organic matter. The
last named represents a stium of the preceding foiir, atnd together
with the mineral matter they are all called nutrient.-s,. The value
and function of each of these classes of nutrients are briellyv discussed
below.
OPPOSITIONON (F FEEDINGt S'TUF'FS.

Water.-All foods, however dry they may appear, (cintain .-oLme
moisture. Air-dry corn meal or wheat hlour, for example, which
may appear perfectly dry will, on thlie conlhete removal if their
water, be found to have containetl from ,5 to 15 per cent. Some root
crops and vegetables may contain as inuich as 5.'i pter cent, tor even
more, of water. The water naturally present in feeling stiil',, may
cause them to he more succulent anti thus douobtles.s aids their diges-
tion, but an increase in the water means a necessary decrease in ihe
actual amount of flood material present, henm e its presence instead
of adding to merely detracts that much from the value of any feed;
especially is this true of thle concentrated feeds.
Mineral inatfr, or asih, is that portion which i., left after ctniplete
combustion of the plant. While a certain allmounllt of ashI i. neesary
for supplying mineral matter to animals andI in bImildlin Iones in the
young, there is usually an abundan(ce present in all foodIs: andI for
this reason no commercial value is placed on the amount of asl c,)n-
tained in the food, as is the case within proteids, carlbohyvdrates, and
fats.
Protein is a name given to a group of very complex co,,il)tpoiunids
which are characterized by thle fact that they all contain the element
nitrogen combined with carbon, hydrogen, oxygen, and small amounts
of sulphur anti sometimes phosphorus. Albumen of eggs, casein of
milk, and fibrin of blood are examples of protein 'coipoutnds. Pro-
tein is that material in the fond which serve.-, as a flesh former, and
is the only substance of thle food that can be used to bIuild muscular
tissue, skin, hair, horns, blood, and connective tissue. It may also,
when in abundance, serve the function of the carbohydv rates and fats
of the food. Alfalfa, cotton-seed meal, all the clovers, and wheat
bran are examples of feeds rich in this nutrient; while prickly pear.
straw, roots, and tubers contain it in very small amounts. Because
of its importance in the dietary, anti the faet that it is not present
in sufficient amounts in all feeds to supply tlie needs of animals, it is
usually the most expensive of all the nutrients. In one State having
34749-Bull. 106-08----2





DI.F.STIHILITY OF PRICKLY PEAR BY CATTLE.


a feeding-stu nil' law a value of 2.3 cents a pound was placed upon the
protein which the f-odI (containetld, while the carbohydrates (nitrogen-
free extract and crudle tiber. and fats were priced at 0.94 and 1.14
cents, respectively. This is about an average of the prices usually
placed Iin these nutrients.
In the Southwest, where alfalfa, wheat bran, and cotton-seed meal
are three of thlie principal feedl, animals usually get an excess of
protein over tihe amniunt %which they require, and this excess is
undoubtedly ulcdI ti serve the function of the fats and carbohy-
dirates--that is, to furnish heat and either forms of energy and to
produce fat. Because oif thlie fact that the feeds mentioned above
are the inmo'4 a1buinldlln ones for thi., section, if a commercial value
were placed on their various, nutrients tlie l)roteids should be cheaper
than thle cirb, yhd.IraLtes and fat-;, ant stuch is often the case. Wheat
bran, iot ton-seed meal, and alfalfa are usually found to be cheaper
than corn and other starchiv grains and hays.
While thlie v'arilous gTroups o lf protcil cominpounds are alike in that
the element nitrogen i-, ci.niiiini to tliel all, thev vary greatly in
thle proportional amaiunt oif nitrogen which they contain as well as in
their value ftir building llesli and itiuscle. Strange to say, it is not
those groups which contain thle most nitrogen that are the most
valuable lor this purpose. Those if most value as flesh former are
tlie -.t-called true proIteids, or albunin-like substances that contain
about 16 per cent f nitrogen. These are most abundant in grains
anld matutire foddler... There are .-impler groups of protein compounds
which thle lheillit calls, ainiis andI ailins, ir better, nonproteid
nitro.geln iomIIpoUIndls. They may contain 21) per cent or more of
nitrogen. 'The are the fir-,t products formed by the plant in the
svnthesis oif nilrogein conipiundls from the anmmnionia of the soil.
They ma V be found inII thle viyoull and tender parts of the plant or in
the fruits, anti in riots and tubers. It has been shown that these
nonproteids(. can prevent tile was-,te of tissue hlien used as a sub-
stitulte fi)r alhnumin in food, but they\- are unable to replace the latter
in building llesli.
'adt is the portion that is dissolved when the dried powdered food
is treated Il with ether. This treatment theoretically dissolves fats
only, buit practically small amotunt- o(f gtuis, resins, chlorophyll,
and oiither substances gto into slolution with this reagent, and the
material thus dis-,olvedl i often and perhaps better termed ether
extract. The fats, like thle carbohydrates, are used as heat and
energy prtoducers-, and they are about two and one-fourth times as
valuable a- the latter for that purpose. One pound of fat yields
4,220) calories."
"Uine .ialorie i- the ainimint if heat; required it raise the temperature of 1 kilogram
Of wal-r I degre-e i';iii igrade, ,r 1 piind ifo water 4 degrees Fnahlrenheit.






DETERMINING THE DIOE.TIBLE NIJUTRIENTS.


('ru'de fiber is the portion of the food that constitutes the frame-
work of the plant. In the analysis it is the part remaining after the
finely ground food has been thoroughly treated successively with
ether and hot dilute acid and alkali.
.\irogtui-free extract is represented by the -ugyars and -t rclirs., and
includes all of those compounds of carbon, hydrogen, and oxygen
that are dissolved by boiling the fat-free material consecutively for
thirt- minutes each in dilute acid and alkali of definite strengths.
All of til.s group of 1,odies, together with that part of the crude fiber
\h Iicli is digested by the animal, are collectively called carbohydrates.
They serve the same function as the fats in the animal system, but
are not so concentrated a food. One pound of carbohydrates yields
about i ,,s(i) calories, hence we sa> that fats which yield 4,220 calories
per pound have two and one-fourth times the value of carbohydrates
as liheat producers.
FUNCTION OF THE NUTRIENTS.

The two main functions of food are to produce tissue and to fur-
nish energy. Proteids alone are used for the former purpose, while
fats, carbohydrates, and excess of proteins can all be used for the
latter. 'The amount of food used for building tissue is comparatively
small, hence the ratio of protein to nonproteid nutrients may be
quite wide, especially for grown animals that are diiiwg hard work.
Since the important functions of any food are performed by the
proteids and nitrogcn-free nutrients (fats and carbohydrates) they
contain, the amount of these present and in a form available to the
animal is a measure of the value of that food.
METHOD OF DETERMINING THE DIGESTIBLE NUTRIENTS OF
PRICKLY PEAR FROM THE COMPOSITION AND DIGESTION
COEFFICIENT.
An average of several analyses of a certain variety of prickly
pear (Opuntia lindheimeri) shows it to have the follm ing composi-
tion: Water, S3.41 per cent; ash, 3.48 per cent; protein, 0.75 per
cent; ether extract, 0.31 percent; crude fiber, 2.64 percent; nit rogen-
free extract, 9.41 per cent; total organic matter, 13.11 per cent.
By feeding this plant to steers we find the following coefficient
of digestion of the nutrients present for this class of animals: Pro-
tein, 5S.25 per cent; fat (ether extract), 67.90 per cent; crude fiber,
41.32 per cent; nitrogen-free extract, 82.59 per cent. With these
figures we calculate the following digestible nutrients from the above
analyses by multiplying each nutrient by its coefficient: Proteids,
0.45; fat, 0.21; carbohydrates, 7.77. The nutritive ratio, or the
ratio between digestible proteids and nitrogen-free material, i. e.,
fat x 2.25 + total carbohydrates, in this sample of the plant, is 1
to 18.3.






DIGESTIBILITY "F PRICKLY PEAR BY CATTLE.


PREPARATION OF STANDARD RATIONS.

.As before stated, thle value of a feed does not necessarily depend
upon tihe amount of proteids. carbohydrates, and fats which it. con-
tains, but rather ui)pon thle amount of these contained in the feed
that is available to animals. If digestion experiments show that
a comparatively large aniount of thlie nutrients pass into the feces,
then in order that tlie animal may secure sufficient nutrients to
supply tlie purpose sought there must be a corresponding increase
of tlie ration. For the guidance of thle feeder in tlie proper prepa-
ra tiion if lIis ration, tlie digestion coefficient has been determined
for liWactically all ordinary feeds and for the several kinds of farm
aninials. Experience has proven that thlie best results are obtained
in feed ing %lhen (lie ,igestible nutrients are fed to the animal in
certain definite amounts. Tables of feeding standards have been
compiled by G ernman and Ame rican scientists in which are given the
daily animounts of each Inut rient required )by our common farm animals
of a given w eight and for a specific purpose. In the feeding of nlilch
cows, for example, thlie standard lixedl by tlie German scientist Wolff
is thie one probably miot used in thi- country at present. It is
based iin o-servation of tlie feeding practices of the best German
feeders. i,'getlhr with feeding experiments by trained specialists.
There i, a pirevahlen )pinion in tih united States that the Wolff
standard fI'r m il'l cows is somewhliat liigher in proteids than is
necessarv fo'r tlie bIe-t American ration. Several attempts have
been made by .cieentists in tlie UL'nited States to determine what the
proper standlardl is for this country. Below is given a table taken
from the Connecticut ,Sttorr-i Experiment Station report for 1894, in
which is given the Germian standard, together with four rations
which have been proposed by different authorities for the United
States.
T1 i 1 -I-r,'iii' u., II /f' imnd'rd rmlion, utip thrr i ith arrirt'ms of soime Americanl
r ilijtjl and a h ,. il 'lirtIl .Mru/'iv t'c I ration per I <0 O pou nds liic irteight

I'gestiich nut rinentsl..
Ia ?rganit a ----- Nutri-
P rotein Fat. hydrates valuje.

Poundriis P'ound, iound,. Pounds (nloris
',lff .-t r ] .Tii nd .iprd .. . .. 1.11 1 4ij 114 I 12.50 29 ,bo0) 1:5.4
A.vtrdgj -if I2_1 A\ni'rluun rltionr- roluni-
pit1kt Iy tlit 'l,''0i l_1i 'i xpIrtuItICDI
Stati',n ..... .... ...... .... 21 2 13 74 13.27 31,250 1:6.9
cragr i i.'1 I r.l tinnh il _l'd ILtn I.'1nnl" T l- I
t 1 i [ '1 -' 1 ...6 . 2en.4 2. 1h .14 14.09 34.800 1:6.5
SAverpt. .I .-.'j: ralinn i -.ftdl in n'nrinniii-
ti in lfi2-11 . .. .. .... 2.. .Qfl I 2 34,350 1:fi.3
'r-.nlt il'lv 'iig.p i lr.J ralion ... ... ". 11 2.11 .5 t 13 i 13t I 2 3l 1. 01.1I 1.5.6

SIn r hii iuppg -ie.i rm tn ion Ihp IiirJ %.i hii ,,ill lie supplied by about f 5 pound of digestible fat and 13
pound% oi dige-.tirle earbobydratles by u 4, pound ol digestible fat and 12.5 pounds of digestible carbo-
hydrates, or by 0 8 pound of digestible fat and 12 pounds of digestible carbohydrates.





PREPARATION OF STANDARD RATIONS.


It will Ibe -seen from the table that about the only material change
recommeiinhdedl by American scientists consists in an increase of the
fats and( carbohydrates. It would appear that this much difference
might almost result from individuality, and the feeder would be safe
in using any of these rations that common sense, good juiiIlgieint, and
his experience with the individual animals would indicate to him to
be best. In New Mexico, where proteid feeds are cheap, the nutri-
tive ratio of the Wolfl' standard would probably not be too narrow.
In fact. namrrower rations than those proposed by him are used here
constantly with splendid results.
By the use of the above table a balanced ration can be prepared
from prickly pear when its dig,,est iblc nutrients are known, by so
mixing it w ith1 other feeds as to obtain the nutrients in the right pro-
)portimi. Sulpolev, for example, we desire to prepare a ration corn-.
posed in part of prickly pear for a 1,000-pound milch cow yielding
22 poutndis of milk per day. Using the Wolff ftaiulard of 2.5 pounds
protein, (J..5 pound fat. and 13 pounds carbohydrates as our basis,
and feeding 100 pounds of prickly pear per d(lay, the cow would get
the following nutrients, as calculated above from the species Opuntia
limihfliitui: Proteids, 0.45 pound; fats, 0.21 pound; carbohydrates,
7.77 pounds. This leaves a balance of 2.05 pounds protein, 0.29
pound fat, and 5.23 pounds carbohydrates to be supplied by some
other feed. Since the ratio of proteids to nonproteids (nutrittivt-
ratio) in this variety of pear is 1 to 21.7, and a ratio of. 1 to 5.7 is
the Wolff standard for such a cow, it is evident that some feed rich
in protein should be mixed with the prickly pear to narrow it down
to this ratio. Cotton-seed meal, wheat bran, or alfalfa could be used
for this pnirpose, but cotton-seed meal, if fed in quantity, contains
so mueli protein that it makes, perhaps, too narrow a ration for the
best results: besides, animals scour when fed cotton-seed meal and
prickly pear alone, and if possible these should be fed in connection
with some cured fodder.
In Bulletin 60 of the New Mexico Experiment Station a balanced
ration of prickly pear is discussed and rations containing this feed
are suggested. At the time the bulletin was written the coefficient
of digestion for prickly pear had not been determined, and in calcu-
lating the rations its digestibility was assumed to be the same as that
of green corn fodder.a That the digestion coefficient of prickly pear,
calculated from the coefficient of gre-en corn fodder, is very similar to
that obtained from actual digestion experiments may be seen from
the table foIlowring.
SSePe Bulliin 77, Office of Experiment Sijiin-. United .Siji-. Department of
Agri'ulture-. p. 82.






14 DIGESTIBILITY OP PRICKLY PEAR BY CATTLE.

TABLE. 2.- Tr1,l nutrients of prickly pa Oi, Opn i l ,i;. r .fri b, d Ji..itiible iitdri-
ents as obtained by experiment, and the i nhli t'li sihbI nnir; ni. ,bninid by tsinq
the digestion coejfficient of green corn fo, il, r
Nltr,,gpn- turbo
Name of nutrient. Protein. Fjat irep FilIer. C yrato-
extrurt. h ydrates.
I rn kl Io a r, i o rt r P r,.nt. f, r irnt. Per crnt. Percent.
Composition............................... ij i 41 2.t.l i 2.01
Digestible nutrients as determined......... 44 21 7 77 I. 1' ,. 86
Digestible nutrients as calculated from d( i
obtained with green corn fodder.......... .4 7 I 7, 8. 63

Fromn the for-going table it may he seen thatI the- coefficients of
digestion of green corn fodder that were used for valeulating the
digestibility of prickly pear in the preparation of a balanced ration
in Bulletin 60 are sufficiently close to allow the ration there given to
remain nc 'h ange d.
The proteids of the prickly pear do not appear to he quite as
digestible as those of green corn fodder, the fats are about the
same in both, while the nitrogen-free extract is more for the prickly
pear, the crude fiber is less, but the total dligestihle nutrients are
about the same, being slightly in favor of prickly pear.

PLAN OF THE EXPERIMENTS.

THE ANIMALS I'SED.

Five different digestion experiments are inclile(I in this study.
In all cases wild range steers from 2 to 3 years (,1ld were the animals
selected. Tlie steers being ve-ry wild were quite difficult to handle
properly, but it seemed impossible to get tame steers and at the same
time those accustomed to eating prickly pear. In fact, a gentle
steer is practically unknown on tlhe ranges. Plenty of milch cows
were available, but were not used because of thlie difficulty of keeping
separate the liquid and solid excreta. Both sheep an(di goats eat
prickly pear, but none that could be used in this work were found
convenient; besides, steers were preferred, it being deemed more
desirable to get the data for cattih, since they are fe(l this plant
more extensively than are any omher animals. Experience hlias shown
that there may be a slight difference between the digestion coeffi-
cient obtained from sheep, goats, and cattle, yet for all practical
purposes this factor may be assumed to be the same for all ruminants.
Two steers were used in each of thle experiments so as to minimize
anym difference due to individual animals; or. slight errors ldue to
manipulation. It is usually customiary to use two animals in this
work; sometimes more are used. anid of course the larger thle number
the more triustv worthy should be tlhe result.





PLAN OF Tl F EXPERIMENTS.


THE DIFFERENT RATIONS USED.

The first experiment was conducted at San Antonio, Tex., in
January, 19(16. In this experiment the steers were fed prickly pear
alone for about three weeks. During the last four days they were
confined in stalls and all their feed and refuse were carefully weighed,
the feces and urine bein- collected in a manner described later.
Experiment- Nos. 2, 3, 4, and 5 were all conducted in the -;priin
o(f 1907 at the Agricultural Clhuv.r, of New\ Mexic,. Grade Hereford
steers were used in each experiment.
In experiment No. 2 prickly p,.ir was fed alone, as in experiment
No. 1 conducted at San Antonio the previous year.
In experiments Nos. 3 and 4 prickly pear was mixed with other
feeding stuffs (alfalfa in experiment No. 3, cotton-seed meal in No.
4), to determine what effect, if any, these feeds might have on the
digestibility of the prickly pear, or vice versa.
In experiment No. 5 the digestibility of the alfalfa, which was fed
with prickly pear in experiment No. 3, was determined.
The digestibility of the cotton-seed meal when fed alone was not
determined as was d(lone with alfalfa, it being decided to accept the
digestion c'>eiliients secured lb\ other experiments for this feed.
Summarized, the experiments were made to determine-
(1) Digestibility of prickly pear (Opuntia lidlieimeri).
(2) Digestibility of prickly pear (0. .eis?).
(3) Digestibility of prickly pear (0. ,i'i1, iiiii';; clcloides) and
alfalfa.
(4) Digestibility of prickly pear (0. ,wiib i.i. iiii,;;nlidfs) and
cotton-seed meal.
(5) Digestibility of a fair quality of second-cut alfalfa.
DESCRIPTION OF THE STALLS.
A good idea of the stalls used in these experiments may be obtained
from figure 1. They were made of proper length and breadth so that
the steers could lie down comfortably, but not wide enough to permit
them to turn around. The stalls used at the college were about 81
feet long and 4 feet wide. Most of the floor, which had a slight inclina-
tion from both front and rear to vard the center and to one side of the
stall, was covered with thick rubber cloth. The inclination of the
floor allowed all the urine to run to the middle of the stall, where it
was caught in a galvanized iron trough and conducted to vessels out-
side the stall, as shown in the illustration. The urine trough ran the
entire width of the stall near the center and just beneath the floor.
A narrow 1-inch strip was nailed across the floor of the stall in such a
manner as to prevent any liquid feces from running into the urine






DI-iESTIHILITY fIF PRICKLY PEAR BY CATTLE.


tro uglI. The' side and back walls (of the stalls were lined with gal-
vanized irn %i hrever there was anyl danger from spattering of feces.
Thle feed trough was iuade perfectly tight, and so placed that the
animals Ciuld eat with c,nifort and not waste their feed. The stalls
were c)v-ereil and placed in a position ti, make the animals as coim-
f ,rtaihic ;,s p,,,-ililc


-C-

*~~~'** -y~


FIG. 1.-The stalls used in experiments Nos. 2 to 5.


THE -FEEDING.

The preliminary feeding period which preceded the experiment
proper was never less than seven days, usually more. In this time
there was little possibility of any other food being left uiindigested in
the animals' systems. The steers were then placed in the stalls and a
weighed amount of the feed was given them twice each day, a sample
being reserved for analysis each time before weighing. The prickly
pear was first prepared by singeing the spines by means of a brush
fire and chloppinz the singed stems into small pieces with a large knife
or root chopper. A quantity of this feed was kept before the animals
most of the time for a period of five days, the refuse being removed
and weighed twice each day.





METHOD OF COLLECTING THE EXCRETA.


COLLECTING THE FECES.

After the preliminary period of a week or more the steers, which
during this time had the run of a small inclosure, were placed in their
stalls,but the feces were not collct t(d for twenty-four hours afterwards.
This was assumed to be the feces from the first feed that was weighed
to them the day before. While this is an unsatisfactory method of
determining the first weighed feed, it seemed the best that could be
done, and it is believed that the error re-ulting, if any, was not large
when the sum of the feces for the five d]a%.s was taken. It is a difficult,
matter to mark the hbgiing of a digestion experiment with steers.
In experiments of this kind with man or animals other than ruminants
it is customary to use charcoal or some indigeltil1e material of a dif-
ferent color from the feces. which will give a distinct line of separation
between feces from weihlied and unweighed food, but with the steers
the marking of the weighed feed was not so simple. The experi-
ment was tried of giving a small handful of weighed uncrushed corn
as recommended in Minne.,,ita Experiment Station Bulletin 99, but
the method was found unsatisfactory in this instance because at times
the corn did not appear for three or four days, and then it did not all
come t oget ier.
UVtially in digestion experiments with animals it is customary to
fasten rubber bags to them by means of a harness to catch the excreta,
but this was wholly impracticable with any ra nge steers that could be
obtained. Hence it was necessary to arrange the stalls as well as
we could for the separation of feces and urine, and to keep an attend-
ant constantly with the steers during the entire experiment. The
work was made unusually difficult because the steers were wild and
somewhat nervous all the time. Then, too, as the prickly pear
caused diarrhea or "scouring" in the animals, extra care had to he
exercised to prevent loss of feces from spat tevrig and otherwise; but
it is believed that with the precautions taken the method used was
quite as satisfactory as the method of collecting in bags.

COLLECTING TIHE URINE.

Since the digestibility of a food is shown by the difference between
the amount eaten and the amount undige-4std, all of which is found
in the feces, there can be no object in collecting the urine when the
digestibility of the food is all that is sought. This is therefore
collected only when it is desired to know something of the metab-
olism of the nitrogen of the food. The solid matter of urine other
than the inorgnic salts is principally urea and other highly nitroge-
nous compounds resulting from awaste of muscular and other nitrog-
enous tissue, the kidneys being the principal organs through which
3474q-Bull 106-08--3






DIGESTIBILITY ')F PRICKLY PEAR BY CATTLE.


this waste is excreted from the body. Thle excess of nitrogenous
matter from the dige-te'l proteids of the food may also be found in
the urine.
In the experiments the urine was collected, weighed, and analyzed
for the purpose of -tudying the income und outgo of nitrogen with
the different feedIs, in some of which the proteids were present in
very vnmall amoiiunts, while in other., the nutritive ratio was much
narrower than that given by Wolff for oxen at rest in stalls. The
results of this study of nitrogen metabolism are given in Table 17,
;mnd are discussed under "Income and outgo of nitrogen" in another
part of this btilletin,.

PREPARATION OF THE SAMPLES.

Saimple of the feed .,nd refus-e were collected twice daily, and of
feces and urine once each laiv. After n moisture determination
had been made on the sanimples of feed and refuse for each day the
dry matter from them all was mixed for one composite sample.
The daiilVY samples of feces and urine were analyzed separately
in all experiments except for the urine in experiment No. 1. In
this instance one composite sample was made of all daily samples.
In collecting the samples of feed, refuse, and feces about 200
grraims of the fresh material were taken in a large porcelain dish and
placed in the hot New Mexico sun where it soon reached an air-dry
condition. The dry material was then pulverized and was ready
for the unlyve-;, which were made according to the methods of the
Association of Official Agricultural Chemi-.ts.

REPORT OF THE EXPERIMENTS.
EXPERIMENT NO. 1.-DIGESTIBUTrrY OF PRIt KLY PEAR 10/)",int lindhIt'imeri'.
This experiment was conducted at the ranch of Mr. Alexander Sin-
clair, near San Antonio. Tex. This locality was selected because in
that section the prickly pear grows much more luxuriantly than it
does in the vicinity of the New Mexico Agricultural College, and cat-
tle there are more accustome'l to eating the plant than are the cattle
of New Mexico; in fact, the steers that were fed at the college had to
ihe trained to eat prickly pear, and in consequence ate not more than
half the amount eaten by the Texas steers. Moreover, during part
of the time. at least, what they did eat was little relished, except
when fed in connection with some other feed.
In this experiment two 3-year-old range steers, weighing about 800
pounds each, were used. They were fed for a preliminary period of
ten days before being placed in the stalls. The experiment began at
noon January 2, 1906. and continued until noon of January 6. The






DIGESTIBILITY oF 1'RIKLY PEAR A )NE.:.


steers were placed in a barn with plenty of light and air, and were
well protected from the cold. They remained in good condition dur-
ing tlthe entire experiment, except that they scoured quite badly, as
animals always do on an exclusive prickly pear diet. The fact that
these animals scoured is not suirpri-ing when one considers that in
eating 100 pounds of prickly pear. the ivcragc daily ration during the
live days, they consumed 2.')5 pounds of in,,rgpnic matter or ash,
which doubtless means more than twice this amount of salts more or
less purgative in their character. The steers also obtained ,i.4
pounds (or over 10 gillniis) of water from 100 pounds of prickly pear,
and this would doubtless aid the salts in their puirgitive action. The
water ol)tained from the feed was more than was drunk by the steers
in experiment No. 5 *where alfalfa alone was fed and in which an
average of only 48 pounds a day was drunk. The steers in experi-
ment No. 1 took no water during the experiment except that obtained
from the feed.
In Table 3 is given the composition of the composite sample made
up of daily samples of the pear fed and refused during the four days
the animals were in the stalls. There are also given analyses of daily
samples of the feces from both steers. From these figures with*the
weights of the dry matter in feed and feces have been calculated the
data given in Table 4.

T.ABLE 3.-Ef Ji ruIr,tiW No. 1--'rri ip,,in p of thw prickly pecr fed. oJ the f,. and
qi ii,, J.ces.
[Nutrients reported water free.]

Water. Ash. Protein.a Fat.a Crude Ntrogt Organic
fib extract ELt* r.

Per cent. Per cent. Per cent. Per cent. Per cent. Per cent. Per cent.
Prickly pear, as fed............ 86.38 2.95 0.72 0.19 1.77 8.02 10.70
Prickly pear, water free .................. 21.69 5.27 1 42 13.00 58.62 78.31
Refuse water free-
Steer No. 1 .......................... 21.69 5.27 1.42 13.00 58.62 78.31
Steer No. 2 .......................... 21.69 5.27 1.42 13.00 58.62 78.31
Feces steer No. I-
First day ..... . 85.76 36.91 6.28 1.51 22.94 32.36 63.09
Second day................ 85.59 42.64 6.28 1.30 21.73 28.05 57.36
Third day...... ....... 88.63 42.79 7.79 1.57 19.38 28.47 57.21
Fourth day ...... 86.65 42.34 5.97 1.27 21.06 29.36 57.66
Feces steer No. 2-
First day ...... .... 82.83 45.93 5.85 1.24 21.46 25.52 54.07
Secondeday................ 81.39 45.33 6.40 1.31 20.91 26.05 54.67
Third day................. 88.89 36.74 7.79 1.36 19.82 34.29 63.26
Fourth day................ 87.62 35.32 5.58 1.18 23.47 34.45 64.68


elsewhere in this bulletin to 1-note, respee-


aThe words protein" and "fat" are used here and
Stively, etrude protein and ether extract.








210 DIGESTIBILITY OF PRICKLY PEAR BY CATTLE.


TABLE 4 i'ciffiht of /thtjl.e, rtsfu> .,, awl fl'ies in 1 ,, 1,,? .Vo. 1, ii i'M te ca l'ItUed
slp qi vtl n o ,)ijlii' i l,.

STEER N'' I


SIPFv' Crude Nitrogen- Organic
I~ni r x ji crr .. Li ifil' |r irc r mianer.
eXtract.


Gram, F Gru',4. Gl
*t.5. A. .3-51 7 i 5-.541) 0 1


lo'.Al pi',rkly r rJr rITi-l . 441
Tol.Il rrit kl. prir v.lvI'in 2".. 1111 4


P7r'. t-.
Fir-s hy
-' r 'i .i . .. .. .
frf,..'t1.J l.r. .. . . .

T h rI r . . .
Foin h .1 ... .


I'gL it-t' i .

( r'il lTl I' i ll I l ,r
St'[ lI . . . . .


1 ,'ll .1 .
1. 4r. 2
2,0,.. 7
..,: sn,, I




,,4 11


O) 7
! :,, 4 4 ;** I,.


70i.. 2
n..5's I
"".$ I

1 1 '4

4,, 4(14 ,


',:. 46


'ra in Gr irm Gram, GroIms..
i4 1 3Q2 7 :, T20 C. 14.973 1
2 6 :3 57 4 25, f,
r02 J .0" 4 .3,2t. 2 14.714 7


121'i 2 2_ 4 i. j 119 1
9.7 I 2U 1 336 ( 433 7
I'0 C .1'2 1 'fl 9 3'. 5
In. 0 .s4 Z 5.i5 0 .l. 5

541.1 lit.. 1 1,7419 2,441 .8
7,. ; 240 1,?11 4 P2.272. '


,'1 0. 1-. 2 U 41. 31 $>3. 4!l


STEER N-,,. 2


' iti.l Frr'klI p, ir f,, . 2 1, 122.1,

T, .lI pr l|.. kl t.r r ,l' il. 2-',', 42
'f.,.iui ;'rzs l. LI ,,.,-r tI' nt'l 21,5.1,$ 2


F r-i. 1 ....... .. ,'7. A
S.'. on I.'. .I ....... '2, 5s10. 5
I h i r.l ........... .... 1,7 4
Fi. rT h 1. ....... ........ 5

I '.i I '-'... l .... '.3-'.27 4

( ,,'Ti, no Il if ,ll'r'_ I I, i [,>r
f, Ml[ I Ill el
A.\\ ro.'f 1.,.r ceiril 'digi'-le-I I'-
I A oi t.-Frr... r' )^


u,-"'7 :;
1;.," ',

". 1114 4


7 ;,j
l,0".1 6
,'i2 9



';, 5l7, '



75 .7


I,."7 I

1,24. 2
1,24ll 2


346 '. 3,174 )
I 1 6 i 115 i ;

,S 2 3,5IJ9. .4


1''. .1 21 I
15.; U .11 .1
1.16 .; *24 4


_527 1 ln,
717 V 7 '2 .> 6

57 47 64. 3'


I. 90


:<64. 3.1
41"I' 'I
3146. "
51 4 .1

1,7'. 3
I ,:2?,4. rn


14, 116 5 19,125.3
5)21 i 696.7

13,71.9 18t,428.6i


4 2 91i7.9
622. 7 j 1.306 9


rDUi U
','. 6

2,513..5
II ,2_l. 4


41. 2 SI 7A


41 32


1.106 9
1,10.2

4,191.9
14,236 7


77 03

74 12


N'.TF \',' 4 gir iit- 1 ']1 1 1 ,' rid

Thei figures given above speak fairly well for the digestibility of

the prickly pear. The (co)efficient for dry matter is equal to an
average of that obtainedl from our best feeds

Thii experiment shows that the digestion coefficient for thle ash

of p)rickly pear is low, but this was to be expected because of the

large ainmount of ash always l)resent in these plants. Animals assinm-
ilate more ash from prickly pear within the low digestion coefficient

of this nutrient than they obtain from other feeds. For example,

tlhe ash assimilated from 100 pounds of prickly pear by steer No. 1

of this experiment amounts to 1.11 pounds: while steer No. 1 in

experiment No. 5, where alfalfa alone was fed, assimilated only 0.63

pound from 15 pounds uf alfalfa.


Totl irir'1 i:. pear It


Gram s.
20,002.7
3.145.6

19,657 I


1,207. 1
886. 9
1,180.6
1,574.2

4,848.8
14,808.3

71.21


%






DIGESTIBILITY OF PRICKLY PEAR ALONE.


The digestibility of the other nutrients is found to compare very
favorably with other standard feed-, the coefficient for nitrogen-free
extract being unusually high.

EXPERI'!E1 N.) 2.-DIGESTIBILITY OF PRICKLY PEAR (Opuntia lxvis?).
This experiment and the three following were all conducted with
the same two steers. They were grade Herefords that had been
grain fed and were ready for the market at the time the experiment
was begun. This fact rendered them less satisfactory for feeling
on prickly pear alone; and to make the matter worse the feeding
was done in the spring, when many of the joints were yVoung and
least palatable to animals. In view of this fact the daily ration,
amounting to only 53.52 pounds for steer No. 1, and 72.18 pounds
for steer No. 2, was considerably short of enough for maintenance.
The animals lost flesh rapidly on this ration, but unfortunately we
can not say just how much, since they were not weighed after the
experiment. However, by.reference to Table 17, it may be seen
that the excreted nitrogen during the five days was in excess of the
nitrogen of the feed by 46.9 grams for steer No. 1 and 63.2 grams
for steer No. 2, making a daily loss of 58.6 grams of proteids for
steer No. 1 and of 79 grams for steer No. 2.
By referring to Table 5 it will be seen that both steers received
much less than a maintenance ration. Steer No. 1 ate only 6.64
pounds of dry matter, when for maintenance he should have had
15.1 pounds. Steer No. 2 ate 9.36 pounds out of 16.7 pounds required,
and the nutritive ratio of the dry matter was 1 to 33 for both steers.
The results of this experiment agree fairly well with those obtained
at San Antonio in experiment No. 1, the greatest difference being
in the amount of protein and fiber digested. The increased amount
of fiber digested in this experiment might be explained by the fact
that the plants were mostly young and succulent joints in which the
fiber had not developed to such an extent from the more digestible
hydrated cellulose. Steer No. 1 obtained 46.3 pounds of water from
the prickly pear eaten. He drank in addition an average of 7.6
pounds daily. Steer No. 2 obtained 62.4 pounds of \vwnter from his
feed and drank in addition 5.4 pounds.
TABLE 5.-Experiment No. 2-Composition of the pri'-lJi pear fed, of the r. .. and of
the feces.
[Nutrients reported water free.]
vv,.'r. .\-h Pr.'I, vi. F-t lrll- N i N r.rng e n-r r .mr.
fih~r. In (a~trp.
extract.
PeTr cent. Per nr irn r r Fnf P(r 'ent Prenlt I',r nj I'r f, 'ii
Prickly pedr fed. ...... 86.45 2.85 0.57 0.23 2.25 7.65 10.70
Priekly pear. water fre ................. 21.05 4.22 1.71 16.61 56.41 78.95
Reus..e. watr-r fr,,,-St r NoI 21.82 4.64 1.46 17.14 54.94 78.18
Steer No 2. J4' 781








22 DIE;ESTIBILITY OF PRICKLY PEAR BY CATTLE.


T\BLL "').-Ec,(,;,ient No. 2-Crojpto ition oif the prickliy pij,-Jftd, of the refuse, and of
tht'',f.t s-- ",inIinued.


l'a'tes tif ;t,' r N'. I
First dJay ...... ...
Scc nd 'Jay .......
Third day....... ..
Fourth dla. ....
Fifth day . . .
rtFois of st'- ..r N.. -
Firlt da. ....
Sc-roiid da. .
Third liy. ..
Fourth ,].y.
F ifth d ....


\ t,'1 .A .1]


Pr'rri Ptr, ri
.t.* .,2
: i. 44 1.j
7 i 74,i
7-4..Y5 II 7c
72' ,ll jl u.'


1011 rid.N t rogen- Organic




1! 1.3. 311. 313.90 1G. 15
Iro ,,7 1.28 1...22 ?8 14 5&.7. 51
7 42 1. 1 .fl.4 30. 8 61.-
.. 4 1.77 .0. 37. i 6 26
.! 49 i. 77 20. 07 7. 931 6.2
1%.6l 1I.9 24 52 35.30 68.58

;.," 1. 41 21.38 '2.78 62.93
1. 71 1 if. .07 ;10. 24 58.25
5 '*1 1. 4A 1,..J(2 32. 86 59.99
3 I .1 .4 1' 56 41.67 68.68
* il 1.':6 -4 ,7 29. 65 61. 14


TABLE i.- lW i't(/i II, ", I/ii, rj'. om ,I J(t s i n ( ( r i it . wiu'lth Me calculated
iSr'it' STEER NO. 3.


liot Il pritkly [.-,, r ,I L . .
'. I i |ri M y pi'c r r-tI' .,J .
rr.t it pri, kl. pea.ir e.,tpn
.I-et e-
Fir-. i ....
,.. on,]l y v .. . .
T hird ,IJ.y . . ..

F,oit h do
Flb .1 1. . j
1 ,,t ,i I l'r -< >* dj rn"'pp'i.

T .i I .ii;-- l .l .i.-
i ,-lhi in ,I' lgt'i-lti.n ,i,(r
il i .


[Ivcrude INi,,trrogen-I Orai
Dry ..:h. l'rotein. Fat. Cue Nete rgani
i t.e, fiber., tract. Ma ter.


GCrm,. Grami. Grami. Gram. Grams. Gramr. Grams.
1 74'i 3 3.94L. 7 79H1.2 320. 'j 3,114.3 10,376.5 J4,802.6
1 .94 I S ,t, 13 171 4 33.9 t,33 2 2.029.9 2, &.. 4

.1 3 0 111.1 t, hl]i._,- .h,.. 7 _'2.4?l. ', 8.546. t 11.914.2


"912 i; .31..3 ,3: 12 0 172 j 309.5 558. 1
] 27., 3572.9 S.5 16.5 247.5 362.4 714.9
t.1O u 2rlt. 3 31 2 10.4 119.3 212.6 423.5
'17 3 291.2 77.9 Il. 2 114. 1 34M. 1 ,26f. 3
1.,'_2 1 4.34 3 94. 1 2 0 339.0 4S7.7 947.8

I. 1 1) .'19 4 37.. 1 k2 2 1.09 7 1,720.3 3.270.6

.,i,.4.1 1 "' 2- 244 14 I 5 1,310t.4 t,82.3 8, b43.6

'.7 5-2 3 Sti 30 43 i.7 I 1 5.3 i9 79.87 72.55


STEER NO. 2.


I ,Ini ,rl k ,i ,r l e,] .. .... ..
r' I pri, klI". pe.ar reli-.tie ..

tlotal prii kly pre.,r e.iteln.
I eta.rI l

F ir-,t d.i.y ........ ...
?<:toi d.ar vl'i .. .. . . .:.
T ru i r 'l, Y........... .1
Fourth day .. .. .. .
F ift h j. ............... I

r-ral itfr';" drnpIH .r

Twail pitkly p, r diger-tl.. ,
CoetlC h.-it ,, 'd ga.ti,',n i per |
fD It ..... .... ... .. .I. .
Av,-ra-co.'rfic, r ntni thgai- ion


2.5.'. 0

3 1 _-,2 3 j_


1.5351
1, 764. 1
1,2 -'," 0
1,431..1i
A%!. 4


.OuijO 2
-32 0

4 148 2


3.1i. 3
;44.9
491 3
149'. 2
730 3


7 ',42..3 .. 2.0

1.3, 241 T 1 4.',t; 2

,.2. 40 12.74
t1. ',i, .:.',. i


I.,l.2 4 40i 2 3,.i 43. 5 13.I 9 .3 18,753.6
117.4 ji. 9 433 6 1.39L1 0 I 1.978.0
_') 0 .3-9.3 3.511.9 f 12.O9.5 16,675.6


113.2 23 2 ,12. 3 .509.5 978 2
103.1 21 7 375.9 539.5 1.039.2
72. t. 17 2 243.4 403.5 736.7
84 8 22. 1 280.5 597.7 985. 1
I W; 9 31. 2 496;.& 5 2 1,251. 1
.)10.6 122.4 1.718.9 2, ;3N. 4 4,990.3

374.4 21b.i 9 1,792.0 9,371.1 11, 7,S5.3

12..>1 I0. N "1.02 S.0J 70.12

40. K tLA.(12 'J3.99 .S. 7.5 71.39





DIGESTIBILITY OF PRICKLY PEAR AND ALFALFA.


EXPLRI M% 1\T No 3.-DIGESTIBILITY OF PRICKLY PEAR (Opuntia wmiIm iif ; ,1, i,. .I,
AND ALFALFA.
Since prickly pear will not furnish a balanced ration when fed
alone, but requires some feed of a relatively high protein content
as a supplement, the effect of alfalfa on the digestibility of the prickly
pear has here been tried. Steer No. 1 was given an average of 4.5
pounds of alfalfa daily, while 4.72 pounds was given to steer No. 2.
In addition they were given all the prickly pear they would eat,
which was 42.16 pounds for steer No. 1, and 57.18 pounds for steer
No. 2. The prickly pear used was Opuntia engelmannii cycloides,
which is a larger stemmed plant than most of the native prickly
pears, and the animals seemed to relish it better than they did
0. la vi,.', the variety used in the preceding experiment.
Tlhe results obtained in feeding this ration to steer No. 1 were
for some unaccountable reason very unsatisfactory. The dry mat-
ter digested amounted to only 56.81 per cent and the ash to 16.S7
per cent, while the protein coefficient 'was minus 16.54 per cent.
This negative value for protein means that the protein of the feces
amounted to more than that of the feed, which, of course, is an
error. Whether this was due to blood or cleavage products in the
feces, we can not say. Tlie percentage of nitrogen in the feces
was unusually high, but duplicate analyses of these were made that
cliecked within reasonable limits of working error. Only 29.92
per cenit of the fiber was digested by this .iniinal, but the amounts of
fat, nitrogen-free extract, and organic matter seemed to compare
favorablylv with the o)efficients of these nutrients from the feed of
steer No. 2. Assuming the digestiblility of prickly pear fed in this
experiment to be an average of the coefficients for the two varieties
determined in (experiments NXo0. 1 and 2, we have by the use of this
factor calculated the digestion coefficient of the alfalfa that consti-
tuted the other portion of the ration. The coefficients obtained
for alfalfa with steer No. 1 are quite as unsatisfactory as were those
obtained from this steer for prickly pear. They were all far below
the normal digestion coefficients for this feeding stuff, the results
for ash beiling minus 38.9 per cent. While the results obtained from
steer No. 1 with this ration are all recorded in the fil',\wing tables,
it is very evident that the coefficients found can not be used in the
calculation of rations of either prickly pear or alfalfa. We have
therefore omitted them from all averages.
With steer No. 2 the results show an increase in the digestibility
of the nutrients of both feeds, and this is just what might be expected
with this ration.
For a comparison of the dige-ti, n coefficients of prickly pear and
alfalfa obtained in the following table with those of prickly pear
obtained in the other experiments and of alfalfa obtained both here
and at the other experiment stations, see Table 14.







:4 DIGESTIBILITY O(F PRICKLY PEAR BY CATTLE.


TABLL 7 .---. E pu jniml No. .3-(oi' post oilt 4 hf tit rrkill pfir oil alulJ'ija fed, of the
re/l'isr., and orf eh0: lt.t.r
[Nu[rt'.nt': ri ert.'d water ir..e ]


Siter. Ash. TFrotein. Fat.


Crude Nit rogen-I
Crude N'ree e- Orgnnc
tlher. treee- matter.
truck .


P'r ,tI P'c:rm rti I':.r .-ng. Pt' trl. I'tr rlnt. Pt r ceint.


I'r kl'' |r e r i ,T-r 1 ', r .
\If Ili. ., ,,er tr '
H ri14t- ti prt kl'. .F. r. r reers
N ,".; I [i.i ."..
H e -l ,-e f ill .1l N-r- I' 1
". l 2. .
'etLe- ,,I -tPor N,.. I
F ir-t . . . . . .
`-ut* ori-I dlu ''
Third! Ii

1 ',r 1, i ... ...

IFt-Le. -4 .steer N.. -2
i' t ...
? l ,,T n .i ,1 ,,'. . .... ...
'hrn .rj ,I.n . . .
F',,i rth ,I iy .. . .. .
Fi'if] ,i .1 .


N r, ep. 1a ,. 7, 2.9q
\Niinp. 10 Ul 1. i.'.


i". 75 2 -4


Nn'lip N.mne. Noti-. '


71 .Sr l'.. it!
a .it. 1.. -
-. 27. .
"0 s'i 2'i. 4'.
0it. h) .. 2


>*-. i i -i-" 4 .l


3. 7 't 27. 40
%, 1. S 2N'-.71
3. 13 S42 I
4' 4, I')


*I. M~l

*'42


*i 10


7 4n
',. 20
24
7.13
;. ('1


I 4.S 12.22 u4.57
21.)7 32. 2$.i 41. 47


1.4'N 12.1'2 C .4.57


2. Is

l ",0

I.'''
I. '-,)

l. Ma

| ',4


Ni-e. .None.



12. '.S 27.72
20. '.2 3;. 32
I.ItU L 31.27
Itt. U "4.4


Jr...--u '24.04
27. 1 34..q
2-,.0U 3',j.'23
2'9 IS :i; 09
il.' 3 11 34


ST.\V L : i Ib ,,l, i h, .I ; i 1. 1 .'" a 'I," ti eht i r v ip i titlet i .No. 3. ii lit cu fl'ul ez'ld
l ,i., 1t ,1 r, ''I i 11, ,' , t 1 r! i tid htf t'. ,., p ir. ta, cly.
rEr-1 N'' 1


II r. \I i 1'rtt. i. 1 it
if.n i[ t,,r


Sru-1- N ro,' n- Organic
vi1..T ; rtro maiti-r.
I. I ran


I.Oriir., dGra inir'.
I',.,.it lIrr.hll ,p i *I !.ry i4 7 t.. '7 l4 i
r.,l l L,, I. [. r r. Ii1 . 4 I., 2 ia 4

I .-.t id l r, I '. ir l.n I', :.-.'., I 3 4


7,i, r h"
I nl 1.1
4-'.
'",. 7


1, 14 7
I,,trl ,i ill h ii.......... ..... .l' + a >, n N l 1.* tn
1 ,"t il m l i ll r. Iu I .1 . . i _N orn, N ni, N '.,rii

Total alfalfa eaten....... a a' 7 I 0,,4 7

Fre(es:


First day .................
Second day ................
SThird (lay...- .............
Fourth day...............
Filth day................

Total feces roli i..l
Coefficient of digestion of
prickly pear and alfalfa (per
cent) ........................
Total alfalfa ulihlg, 1. .....
Total feces from prickly pear..
Total prickly pear .iii -ti .i
Coefficient of .,igi 'tin .il
prickly pear (pert i iI ...
Coefficient of .lit,. -tonr of al-
falfa (percent) a.............


2- 11.1 '



2 ',iM I)
2 I1'; 0


1-, i'7. l,


4 -.
1,2.
1 1. ;


771 I

0.17. 3

,'.11) 1
S76. 2

. .77. 3


t. 4 21 4"
,7-1 ,t 17 r.
il1. 1 ,t 7'. 7
'2-. 1. -24 a7


Vt .V,1 -l."i ta7

9. .i") .l.S 90"


i It-, 5
?i.0.

1',4 2


27 .,

1. 175.0'



40 '-4
470. I
'1.4 '3



-In' .1
2- 176


2,. 76


ri, ri It 'rr i irv
.A i 4 1.4 1
210 7 I 7 ;4' 7
2-2' 4 *2 414 4

2vJ 5 .1 l .'.
N ori-. N ,, ,i'-.

n-'1 i 5 l 12'


4.: I


'.11 ] I
4"l 0

4; .






51 4I
li;. 4
7t. 1


I.,


f<; rjm, (; ro rtl .
21 '-.C 4 27,620.7
9 I12 h 11 567.2

I-2 :,7.7 15 (, .15

4.'111 u 8.708 3.
Nun-' None.

4 'il'. .71-S .3


<.'3 i '27 t
4.1 715 7
12., 2 7'r1 1
t'44 1 021.2
'1. h I U21.4






..rl U l 211.4
6i12 L 2.f 67. 41
722 4 it. 7'90. 4


2- 92 7- 74


2,.. "-4 26 t5


57 04 42 24


a Calculated on iii It ,- sirtipt1,l1i t h.t i tf" Ca,, -tii'i.'tt a I dtig'Qt in i-.l fthi prickly pear used in this expert-
ment was andl-rqgi- 01 o ,-w twto V nr-ite i,',d in experiments Nos I and 2.


Per cent.
A1. 25
S9.91


M. 25


Nne.


b4.38
72.13
70.54
73.15
74.20


70.35
72.. bO0
71.29
76.16
71.90


1. :i9';. 8
1,869.8
1.454 5
2,179.9
2, 232.3

9. 130.3



i. 57
3.,675. S
5,454.5
9,599. 0


63.09







PRICKLY PEAR AND COTTON-SEED MEAL.


TAHI r. A.-'177iq1t o1f it *f,.t l. i ',".,'. and feces in experiment A,,. 3, with calculated
digestion coel)liii n'. of bol, jit/Is used and of each separately-- ',iinul I.

STEER NO. 2.


Dry Ash. Protein.
matter.


Gr,*i, Grl n. G, ril in
Tolal prickly pear fed......... 39,146.1 7,339.9 1,166.6
rotal prickli- pear refused..... 12,033.3 2,256.2 358.6
'l'otal prickly pear eaten. 27,112.8 I 5,083.7 808.0
Total alfalfj fed.............. l15 ~ 1,024.9 1,431.2
Total alfalfa. refused........... None. None. None.
'"1 ota alfalfa eaten ....... 10.1 i7.3: 1 i'4 1.411 2


FrCeS:
Firs[ day .................. 1,948.5 577.7
Second day ................ 2 ,il C. 713.7
Thirdday................ 2,820.2 809.7


Fourth day .............
Fifth ,lay... ...........
Toal feces drupp[il .
Coeflicient of digestion of
prickl y pri r and alfalfa (per
,_- iD t ') .. .. .. .--- -. -. .. .
Total alfall' unnliig-st,- .. ...
Totial f-cert from prickly pear.
Total pri: kly pear thgest,-d
Coefficj-nt. of digestion of
prickly, pear (percent) .....
Coefficient of dig,-st.n of al-
fal[a I per cent) ............


3 1]. 4
2,160.1
12 721.8


65.87
4,481.3
8,240.5
I, 872.3

69.61

68.41


760.1
607.0
3,468.2


43.22
626.7
!11 i
24221
2t2- 2


44.11

80.59


144.2
213.6
232.4
2297.3
153.2
970.7


56.65
493.0
477.7
189.3

40.8S


Fat.


Grai -.
579.4
178.1
401.3
210.2
None.
.'11 2


37.2
46.9
51.3
56.1
35.4


226.9


62.89
147.2
79.7
321.6

80.14

52.28


Nitrogen- i
Crude free ex- Organic
fiber. tract matter.

Gramr, Gr G i f Griam,
4,783.7 25,276.4 31,806.2
1,470.5 7,769.9 9,777.1
3,313.2 17,506.5 22,029.1
3,278.8 4,212.2 9,132.4
None. None. I None.
i. 2;s % 4 : 1. 1 2 l 2 4


717.0
721.7
733.3
930.4
687.6
3,790.0


1,9

1,'


472.4
908.7
993.5
1,214.5
676.9
4.266.0


42. 51 802. 6
)55.8 1,270.4
&34.2 2,995.6
179.0 14,510.9

44.63 82.88

37.29 78.65


1,370.7
1,890.9
2,010.5
2,428.3
1,553.1
9,253.5


70.34
3,854.8
5,398.7
16,630.4

75.49

64.38


EXPERIMP'NT No. 4.-DIGESTIBILITY OF PRICKLY PEAR (Opitn/I 'ralriTlmt ,iriq Jbhis} n
AND COTTON-SEED MEAL.

In the prickly-pear regi, i of Texas a ration consisting of this feed-
ing stuff with cotton-seed meal is very common. It is customary and
better to give the cattle either the run of a dry grass pasture or some
coarse feed in connection with this ration, as it will serve the double
purpose of widening the too narrow ration produced from too much
cotton-seed meal and tend to check the sctourilg which results from
the use of these two feeds alone. Bulletin 74 of the Bureau of Plant
Industry, United States Department of Agriculture, gives a num-
ber of rations as used by Texas stockmen and dairymen made up of
prickly pear and cotton-seed meal in varying amounts that were
usually fed together with other feeds. However, in the ration used
in this digestion experiment prickly pear and cotton-seed meal alone
were used, because it was desired not only to determine the coefficient
of digestion.of the ration of the two when fed together but also to
use the weights obtained for. a calculation of the coefficient of diges-
tion of cotton-seed meal, and these would have been complicated by
the addition of other feeds to the ration.






DIGESTIBILITY OF PRICKLY PEAR BY CATTLE.


Steer No. 1 ate an average of 4.7S pounds of cotton-seed meal and
37.28 pounds of prickly pear daily. This made only 14.14 pounds of
dry niatter, which was about 1 pound short of a maintenance ration
of dry matter; but the proteids were in excess of the amount required
for maintenance by more than a pound, and while the carbohydrates
were a trifle short the excess of both proteids and fat made the total
nutrients more than the amount required for maintenance. The
nutritive ratio of the feed for this steer was 1 to 4.49, and he gained
1,551.9 grams of proteids in the five (lays.
Steer No. 2 ate a daily average of 4.99 pounds of cotton-seed meal
and 47.04 pounds of prickly pear. This gave him 17.35 pounds, or
nearly 1 pound more than a maintenance ration, of dry matter
which contained a slight excess of all the nutrients. The nutritive
ratio of his feed was 1 to 5.52. He gained for the five days 1,262.5
grams of protein.
The digestion coefficient for the two steers agreed very closely,
but while the coefficient for the protein of cotton-seed meal and of
cotton-seed meal with prickly pear was about what might be expected,
the coefficient for the protein in the prickly pear was a minus quan-
tity to about the same degree for both steers. This error might be
attributed to several causes. It may have been because the composite
sample of pear used for analysis did not contain sufficient proteids
to be representative of the prickly pear fed. It had only 2.59 per
cent of protein, while an average of the five samples of this species
recorded in Bulletin 60 of the New Mexico Experiment Station had
3.99 per cent, and an average of all prickly pears contained 4.47
per cent protein in the air-dry material. It is barely possible also
that some error may have been introduced here by chairs from the
.shliedding animal getting into the feces. It is also possible that it
resulted from a larger amount of metabolic products formed from a
feed like cotton-seed meal with its high protein content. Steer
Nc. 1, for example, got hardly 1 pound of protein from the prickly
pear during the five days, but obtained nearly 10.5 pounds from
the cotton-seed meal; and the large amount of protein from the
latter source may have increased the metabolic nitrogen in the feces
and thus made it appear that the feces from the prickly pear con-
tained more protein than did the feed, when in reality it may have
been due in part at least to cleavage products resulting from the
protein of the cotton-seed meal fed.
As a further attempt to explain these negative results Professor
Spillman has suggested the very probable theory that it resulted
from the reduced digestibility of the protein of the cotton-seed meal,
due to the laxative action of the prickly pear forcing the other feed
from the digestive tract before its protein, which digests slowly,
had been thoroughly acted upon, but not before the easily digested






COMPOSITION OF PRICKLY PEAR AND COTTiN-SEED MEAL. 27

carbohyvdrntes had been more completely assimilated. Since cotton-
seed m]eal is a substance rich in protein and the prickly pear is very
poor in this ingredient, a very slight reduction of the digestion coef-
ficient of the former would and did result in an apparent negative
result for the latter.
The average of three digestion coefficients for cotton-seed meal
as given in Bulletin 77 of the Office of Experiment Stations, United
States Department of A-griculture, was used in calculating these
coefficients. Since the cotton-seed meal used in this experiment was
adulterated with hulls, as may be seen from the crude-fiber analysis,
it may be that the figures from the above bulletin did not represent
the coefficients for the meal used in the experiment. If, however,
we assume the digestibility of prickly pear fed to be the same as that
obtained in previous experiments, and calculate the coefficients of
digestion for the nutrients of cotton-seed meal accordingly, we find
them somewhat similar to those given in Bulletin 77. It is inter-
esting to note that both of our calculations show over 100 per cent
of the fat digested, which agrees with some of the results recorded
in the above bulletin, and substantiates also the statement made
by Jordan in his work on "The Feeding of Animals" that "pure
vegetable fats and oils are quite completely emulsified and absorbed"
by animals.

TABLE No. 9.-Experiment No. 4-Composition of the prickly pear and cotton-seed
'meal fed, of the rtft.._,, and of the feces.
I Nut rpnis reported water free.]
Crude Nitrogen- Organic
,ter Ash. Protein. Fat. fiber free ex- matter.
tract. matter.
Ptrra I'rr cent. Percent. Percent. Percent. Percent. Percent.
'riekly pear, later iree .. ... 2.9l7 21.74 2.59 2.03 11.44 62.20 78.26
Cotton-sed nimel ....... UO) 6.68 44.25 10.02 11.02 28.03 93.32
Refuse or priekl., pear -.ier
No. I. .. .... .. 21.89 2.85 1.25 12.26 61.75 78.11
Refuse or prickly pear slepr
No. 2. 24.87 2.85 1.51 11.38 59.39 75.13
Reluse of eotton-sped iniul.
steer< No, I nod ?... ........ 6.68 44.25 10.02 11.02 28.03 93.32
Feces of tleer No I:
First day. .......... .;7. i 30.45 13.09 1.28 19.13 36.05 69.55
Second day ....... ? 51i 30.85 12.85 1.55 18.00 36.75 69.15
Third, day. ... ..... I? 0. 31.76 12.92 1.18 18.12 36.02 68.24
Fourth lay .... .. ,? t.3 34.82 12.14 1.13 20.14 31.77 65.18
Filth day ...... 71 ',. 35.09 11.38 1.03 19.83 32.67 64.91
Feces of teer No. ".
Firs t day.............. S1.6.t 26.21 14.76 1.71 21.62 35.70 73.79
Second lay............. 194 30.69 13.38 1.29 19.93 34.71 69.31
Third day .............. l. 13 31.78 14.22 .97 16.93 36.10 68.22
Fourth day .......... .... 2.73 36.10 9.95 1.05 22.04 30.86 63.90
Filth day........... R5 15 34.70 9.86 1.06 19.45 34.93 65.30








215 DIGESTIBILITY OF PRICKLY PEAR BY CATTLE.


'T\m.r \. 10 --li II fj/l fi niIn 1/,Ii. ,1 l',.'r, u i.C'n .s ;,11 u',ei' niil .\o. 'iih nlrulatrd
l,./i ,I nil i ,"f.ll. n //.< (.I" l ERll .'. Ii/& ,1t. l t'l" 11h .'I I iril lil.

STEl(f~l NO. 1


Dry
d I. ti er


Gra m
T'oltui prickl., pOe r I-,t.. .. ... 129.7.. '2
Total prickly pe.ir ra-,lI. . 7.",I "

rut~ii prickl, I,.H pien. !I..-;,7 7
1 01 i r, p cl l I IIl i- I I IP I .... I. ~, I"

ToI.I tIl .',' h- P-a I iivI. I rp i|'r-.l 41h1 s

J o[,1 tril lL/', -<'eil jlhe~ U.


Feet? I ri r< 1 ', ... . . .


'r I, rd dLo
"F.W r ,] d,y.
F LIrf h -11 .% . ... .
Ffth ,iii .. .....
Fi fth 'I i \........


I.,iA IPtr- dIriopple .
Coefficient ,1 *i1irP'ln-'noI rl f I.-
IV pei r., i 'ntii, --in-F .I' I ii I
I i r (t ni i. .
"I'litl trillnn-si-er inp.,l iindl.-
g -steSl d .......... .
l'otiI Ivee" frnni prickly, Ii,.,r,
TotJI pricklN prear ii t'll- ..

('nerlicient of .JigPq ii i A.,, prtrk-
1' l r'iei r i[ lir Ig'ni i .
('l-rfficient of p.] i option *.f tl-
I.>i, ; I l ie .I i I |Pr i tn r i, n . .


2I li
.. 2 1 .
. 1 I 7
1. 544 2
1 .'l .7.


Ash. I'rotelin. Fat.


(Grtnz,. Gram i Gra o n.
I.. 4t'l. Iu 7fI. R I).l 4
1.74 4 227 1 I q ,

I 4.. I 2 -.1 :41..4 -

71% LU ilgJ 4 Il.I' II
31 4 2079 47 I


i ',7 _2 4,.52 1, .O01u i


1,11.2 "Ut.,
7-1..S "'13 1
5.Il. m 210. S

,3.. 7 I 1 3
','1-5 fi n in 2

I, $'.: t, 1. l.-1. 2


Ill 42N 7

I 1.

I1; I'.


:!S 4
24 I
.2. :j
21 .5


Crude
. _her.

Gram.

I1. 1400 2
,1716 -1

2423

I i3S 5
-.1 %


'12 2 72'..; 4, 104. i
2 07'. 1 l 2Q 4

721 7 1,IS 4 I .. 27u 1

4. 7i0. 4 1,U> II 1, 18. 5
'1. 2 2 1 ? 3
I ____.1 __I__'-'. r Ia n., -


I, I Nil .-

2.0 2
5i93 0
421 2
.77. S
522. 2


Ni I rocen-
i ree ex-
tract.

Grams.
IS. 4S7. 2


I.. l .1%W
A. 0 15. 5
SIU. 6


S1. .'13 2,,9.3 9


A.. )u -.iN IU 733. 1
37. A .;K I, 1,5.5
22.1. .317 7 671.3
17 4 '.11.0 490. b
26,. 3 A05 S-3 2

I -r4.' I. S-, 1 .I t,23.7


2.71"'. 52.-. '52k 1 i. 1 '0.1.31
7.722. 2. ,71 .I 701. 7 4t1. 4 1,477..,
I 1.11A'l 1.XI. 1 -2`' .iii 414. 4 '141.. S


1.4 ,': "'e. ll -41. ,. I'S 3'9. M3

72 %,4 47.42 77 ."1 1112 7 17. 04


77 97


1, I :i. 3.
2,487.4
l.flMl.7
1. (IS 1. 7


SI1.67


f.4. S3


- r .F. I N,' -,


I ol I1 lrtk y i P ir I . . . .
Fril pr kh" I 'fit, r p rm iikPI ...
1 1.l'll pr.'rl nl'|.ri lli-iI

'I'll i l tol l hri-sepi.I i l ii l ...

Total cotton-seed meal TePf I <'". I

Total cotton-seed meal
eaten..................

Feces-First day..............
Second day............
Third day.............
Fourth day............
Fifth day..............

Total fc>-'s drnpi-.l
Coefficient of hligeiion (ifi prick-
ly pear and cotton-seed meal
(per cent)...................


l;,-7.1 .7, :'i9 ;
.'77 ') I I. I, 0 ..
. .... LN' I


2l1 'I





'2. : 4
2'. 4 ; I
', Ii;'s 1
2.01111 1


7 IN I.,
1 4


I l 1 1 =" -
.11'i 7 I'ili ;
0'1.3. 2 3It I
790. '15.1 7
1. 109 4 I "iO. .4
"* 3 ',. 2


12.'..'2L .1 4, |.lti. 4 1. 514 I


IS 17 ,


..I. 03


22, 3111. 4
4.323 n

17,93 4

.!. 1t15. U
5.9


3.00q 7

4112. 7
I. 012. 7
s'lS 0
q4& 3
93.11 7


145 .'. 2. 494." 4, ?2,1.4



'.11.41 41.u" 77.97


aCalculated on the assumpti.-n lhl t the lihLy of this variety of cactus was the average of
the two fed in experiments Nos I ainI 2
bCoefficient of digestion for cttlll'-si-l meal u'el inl thew talculationis %a_ taken from Bulletin 77.
Office of Experiment Stations, 1 iii el Siities lieparrtment ol Ngricullure.


Organic
matter.


Grams.
23,260. 0
6,221 I

17. 0.19 5

10,039.4
438.4


9,601.0

1,414.3
1,685 0
1,271.8
1,006.5
1,655.5

7.033 I



73 b0


2. 294.6
4.738.5
12,301.0


72. 19

75.09






28,078.4
5,4ti6. 8

22.609.6

10,039.5
19.5


10.020. 0

956. 4
2,062 2
1. b97 0
1,9 3 7
1,756 6

43& 5.9



74. 15


:' 1. 1 74 '0,1 'II ;l ,I 44 *?.


I






I)G EST, SIITII.ITY OF' SECOND-CUITT ALFALFA.


T w i. N', 10O.-Weight of din fl. (,fi. I,,i.i feces in experiment .\%, 4, with calculated
dluiq i r/h ciioi, ti a l, of bothfeeds used and *" each .,, ii,.I, hi --Continued.
ST E E R NO. 2-Conltinued.


l) ry
latter. :

Grams.
.\\ er.igp .-'i/iet|'llr 11 rl ,lI, '-Ii,1.11
ol prickly pear and cotton-
bed mneal .................... 6i7. K2
'T'oitail cotton-seed meal undili-
gested ....................... 2, 823.9
Total feces from prickly peara. 9,698.4
Total prickly pear digested... -. 18,9 00.8
Coefficient of digestion of prick-
ly pear (per ceint,.. 66. 08
.\ .eri1 ct<,iefi cieil! n. lfh' P- i i,. '
of pri"kly pear (per cent).... 65.29
Coefficient of digestion of cot-
ton-seed meal (per cent). ..b 76. S88


Ash.


Grams.


39. 04

547. 2
3,5539.2
2,449. 4

40. 90


1 i- I,
lroti. Fat. Crude Nr- Organic
ifibr. ir. matter.
Si tract.

Gr mnS. Grams. Grams. I Grams. Gramis.


73. 43 91. 49 44.17 77.97


551,1
963.0
-241.3


39.6I -30.3 :

67. 22 1j9. ,9


72.1
73.4 1,
545.0 1,

88.13


88. 11

104. 6


526.5 1,185.8
9)8. 4 3,095.6
307.7 14 Y' ,

i39. 92 82.79

3". 48 K 2.23

:V. ()i 72.71


73.88

;..11
6, 041.1
16,568.5

73.28

72.74

77.28


a Calculated on the assumption that t1i digestibility of this variety of cactus was the average of
the two fed in xp'ri mnent' Nn< I -Ind 2
bCoefficient ii ,h '-t i, i 1i ir,, nI-- meal used in these calculations was taken from Bulletin 77,
Office of F..Xp,.rl ,int St ii ii,- I itI. I ates Department of Agriculturc.

EXPERIMENT Nil. 5.-D)IGESTIBILrTY OF A FAIR QUALITY OF S.C,,NI-t't T ALFALFA.

This experiment was made to determine the dliiestiwi c,,eflihients
-of the alfalfa that was used in experiment No. 3. The results are
given in Table 12, from flicli it will be seen that the coefficients
obtained in this experiment are about the same as those determined
by other experiment stations. For some of the nutrients the coeffi-
cient is somewhat less than was obtained elsewhere. This may be
accounted for by the fact that the hay used had lost a considerable
propirtiin of its leaves in curing, and the Colorado Experiment Sta-
tion has shown that these are the most digestible portions of the
plant.
The dry matter eaten per duv was somewhat less than a mainte-
nance ration. The proteids were far in excess of the amount required,
yet steer No. 2 lost, and steer NX,. 1 giinel only a small amount of
this nutrient, which shows that the excess, of proteids was evidently
used to serve the function of carbohydrates.

TABLE 11.-- E.i',i r,,I iit No. 5-o(bmt posit ion of the alfalfa f, 'I. of the n.fi.,% and of ih'.
feces.
[Nutrients 11 i.r I water free.]


Water. Ash.


Pr,' lti. P'tr , t
Alfalfa as fed................. 5.09 9.58
Alfalfa, water free...-............ -..... 10. 09
Refuse, water Itree, steer No. 1........... 10.09
Refuse, water free, steer No. 2........... 10.09


(rlA NiILr.-.p'h-
Protein. Fat. 'rude rgame
fiber. r matter.

P', r it it. [e rr it. P. r r int. Per cent. Per cent.
13.37 1.96( 30. 64 39.36 85.33
14.09 2.07 32.28 41.47 89.91
14.09 2.07 32.28 41.47 89.91
14.09 2.07 32.28 41.47 89.91







oU DIG(ESTIBILITY OF PRICKLY PEAR BY CATTLE.


TABLE ]l.-Eiperimnnt No. 5-Compositt.on of lJ'h alfalfa fid, of the refuse, and of Ihe
fetcs--('on t inued


Feces of steer No. 1:
First day.-------..- .......
Second day ................
Third day ... .--
Fourth day................
Fifth day.................
Feces of steer No. 2:
First day -........ .......
Second d a -........----.-...
Th:rd day................
Fourth day ..............
Fifth day.................


alcr. .\?.h Proteir.


P, r(nl Per ,cnl. Per iora!


79. 27


7'p. 7 S

7. 24
77.24'I

X4. N7
W. H1,
81. 97
4.99 i
;4.9A


13.31
11.3;

14 II
l.i. 10 I
15I. 5 0
10.65,


lh 15i
1.3. 19
1 'j. 5i6
S15.41
13. li


Fat


Per ctntl.
2.17
2.11
2 '2.





2.26
3. 11
3 37
3. 3I
.I. 3I


Crude N i irogprn-
rudt ex- Organic
fir. minatter.
trt I .

Per ccnf. PI r c ni Per cent.
44 52 2. 50 86.B9
4 73 33 2S 88.65
45.13t; 27.63 85.89
41. N -9.31 84.20
42 02 32.53 89.45


43. t.
46 67
42.56
41.37
4ti. 7


21. 34
2b. 24
27.S8
2t.. 14
2I k6


83. 8
86.81
84.44
84. 59
86.39


TABLE 12.-Weight o ith, f, tI., .fu ws. and fI; 's in t i i rimarnt N\o. .35, with Ih calculated
Shrt st iont u.ofhi. Ifli.

STEER NO. I


mDat r. .%.h. 'rntemn.


Gram.,. Griali.
Total alfalfa fed ................J2, 2-,74. I 3. 25b 5
Total refused .................. 121 I 12 2

Total eaten....--........... i'153 0 3 .24.1 3

Feces:
First A- 2 D,2 I I,% %


Second day .............
Third day...-.............
Fourth day ..............
Fifth day-.................


2. IC2 1

2,9.1 3
2.H7'' t.
-.: .lI1 b


Total Iirces i ropped. 14,0111 0
T.,tal ipe ted .... . ...... I'l, 143 (1
(.'(Peffi'ient if lige.tion i per' i
tent I .I .. .. ... ... . . 'il-. 43 i


335. 1
414.0
470 .'
311 t;

1,'22.3
1. 422 u


Gram .
1. .7,17 4


4. 3l3u 3


2'4'. .h

13 10
NA) 0
3.|7 'I


I 40.
2.9S3.5


ST43.%3 NK. 4.

STEER NI). 2.


Fat Crude Nitrogen- Oranic
fiher, free e mat ter.
tract.

Gnrnmi. Grams. Gram,. Gram .
6I. I In, 4US. I 13,3R4.U 9, 017. r
2.i 3'.I 29 I 87.8

tfi'.5 fi 10.479.0 13,;B4.9 289,92. 8


46 9
41- 'l
Q2.3
73. q
W9).4
134 *

Jib. 7
**-l.s. 9


962. 6 6l1fi.2 I,.s74.3
1,21,l.h '.l'"2.5 2,617.3
1,322.2 %10.I 2.?0. J
1,227.3 f74.2 2, 5g. 8
1.2-12 9 909.q 2, 667.0

h,0?t, 6 4,2!3.6 12., 187.7
4,432. 4 9. 101 3 I 16,742.1


41.)1 42. 4') t 1. 1 57. 7


T r.t I fall fed .. .. ..
Trtal rpfii- d .l .. .. ..

Tolnl peatien.

Feces.
First d y .
Setiond day ....
Third da .. .. .. .. .
Fourth diy.....
F fifth l. . .. ..

Tolal Weces dropped
Total dipested .. ...
r'-efficient ..f dipgetinn per
eent).
A erape c oefficient of rJdigestionn
iper cent i .. .


3'2,274.I J,25b. 5 4. ,47.4 6tM. 1 10,41U. 13,3M4.0
None. Nine. N.'rne None. None. None.

.12.274 I .1. ?" 5 [ 4. ,547.4 titS. 1 10.41., 1 13,384.0


J,2.5,'. 2 3C.4. 7 ,261 3 1 0 13J. 4 A94..S
I '47 I 2 '.1-.. 2U),. 7 1,1 90', 7 311.0
2., Mt.. 4 41S.2 2'19. 4 9'1 1, 19iK 7 7S5.2
3.245. I 0. I I 375.5 1..9 1 1,4017. 4 1S.2
4. 11 4 5t,4 Q 441 2 139.5 1.931.f 1.073.2

14,417.2 2,124.7 15._6. 1 461.2 6,432.1 3,S.12.4
17, 0,,..I l 11. 31.q 2,1nl.3 206 9 3 9A:, 3 9. 571.6


"',. 33


34 75- 63. 12 30 97


1,V, 29 63). rt; 37.94


29,017.6
None.

29,017.6


1,893.5
1, .90.3
?. 378.2
2,745.0
3,585.5

12,292.5
16,725.1


38.2N TI7 .52 57.63


40. 35 6A. 84 57.75
I






AVERAGE DIGESTIBILITY OF RATIONS U'ED.


EFFECT OF PRICKLY PEAR ON THE DIGESTIBILITY OF OTHER FEEDING
STUFFS.

From Table 13 it may be seen that in feeding a mixed ration of
prickly pear and alfalfa, or prickly pear and cotton-seed meal, the
general effect is to increase the digestibility of all three feeds. This
table shows an increase in the digestible dry matter of all three, and
with some exception there is an increase in the digestibility of the
nutrients in them all.
If the ration of prickly pear will increase the digestibility of all
feeding stuffs, as it apparently has that of alfalfa and cotton-seed
meal, then this feet has a greater value than is shown by its own
digestible nutrients. The probabilities are that the addition of this
green and succulent feed to any dry feeding stuff will increase the
digestibility of both.

TABLE 13.-ti.ruqv iht/,0i/hili"q of prickly pear, alfalfa, and cotton-seed ,iail, and of
a mired ration or" alfjala and prickly pear, and cotton-seed meal and prickly pear.


1-t'r.% ; Ash.
ml~atterr.


P r i e t. Per cent.
Prickly pear ah.ne. .. .. i4.91 35.69
Alfalfa alone 55 S8 39.29
Cotton-seed meal alone. 7.70 23.70
Alfalfa and prickly pear. 'x. 41 80.59
Cotton-seed meal and prickly i
pear .... .. . . . 71.86 57.32


Protein.


Per cent.
49.56
65.56
88.40
60.65

73.70


Fat.


Per cent.
68.46
37.94
93.30
52.28

103.70


Crude
fiber.

Per cent.
47.66
40.35
55.50
37.27

35.55


Nitrogen-
free ex-
tract.

Per cent.
80.77
69.84
60.60
78.65

68.77


ina i ler.

Per cent.
72.76
57.75
76.10
64.38

76.19


TABLE 14.-Siinmarnr of all diyi'stion coefficients obtained in these experiments, together
irtlh loj mio, r irf'iertle i).f alfalfa and cotton-seed meal as determined elsewhere.


Feed.



Prickly Pear t\puntin lindh.tnrri i
D o . . . . .. .. ..
A verage... .. .. ...
Prickly pear 10. Lsin .....
D o ..... ....... ....
Average .....
Averages of both above average .
Prickly pear, calculated from Ieed ol
prickly pear and alfalfa ....
D o . . . .. .. .
Prickly pear, calculated from leed ol
prickly pear and cotton-seed meal .
D o . . . . . . . . .


Steer DrN -
No. matter.I Ash.


Per ct. Per ct.
1 67.12 37.46
2 64.61 33.67
------ 65.86 35.57
1 65.52 38.88
2 62.40 32.74
.... 3o J5. '.l
-64.91 35.69


al 56.81
2 69.61

1 64.50
2 65.29


-16.87
44.11

39.01
39.96


SNitro- or
Pro Fat crude gen- eanie
tein, fiber. freer maic.
__ I ~~~~tract. ..

Peret. Per ct. Per ct. l Per ct. Per ct.
59.03 67.42 41.31 83.40 71.21
57.47 68.38 41.32 81.78 77.03
58.25 67.90 41.32 82.59 74.12
39.43 69.18 55. 96 79.87 72.55
42.31 68.86 51.02 78.03 70.12
I0. x7 ( .102 :3. 91 I 7S 9. | 71..1'
49.56 68.46 47.66 80.77 72.76


-16.54 73.97 29.92 76.74 63.09
40.88 80.14 44.63 82.88 75.49

-41.89 88.08 39.03 81.67 72.19
-38.31 88.11 39.48 82.23 72.74


Average ... ....... .. . 4 90 V.1. 4 1-40.t0 ks. 10 39.21, 81 95 7'. 4C

a The digestion coefficients obtained from steer No. 1 that was fed a ration of prickly pear and alfalfa
are all evidently too lo and should not beusedin thepreparation ol rations from either prickly pear.
alfalfa, or the mixed ieed.







3 DIGESTIBII.ITY OF PRICKLY PEAR BY CATTLE.


TABLE 14.-Summary of all digestion 'ocfiliciintis obta Iiird in Ihcse trperimnent., together
with Some ri

Privkly l ., r iil Aill.if.i .
D o ........ ...... ..........

Average .............-.-------

Prickly pear and cotton-seed meal -...
D o........ ........-. ........ .

Average .......................

Alfalfa .il'-ne ......
lh i . . .
,i pr' i',


Alfalfa lien f, 't tlh i.-riklv pear. .
l i, .- . . .

.\ pr pe

A liiifl, I ..'lr.ial., t % .eriinenl li
[ ion
A lol jI.,
Aliolf.,
Ma \iniunr
Minimum rn.

.\Ieracep..

A.'ilta. Minne nt,t I"xiperiiinPi l e "t.
linn .
Allilfa, Kausai, 1\[heriimei]t lta
lion:
Firstm eatl
beyond Cut.
Thiritut
.Alialfa, IUtali LxlcrirnetL 'taIioii..

(_',lt,(n-ePtd ientl h
Mnnimuni
Minimum
v ra .'e. .

'i'tton--eel meal [r'rni fe'e1 i crIton-
eepid meal %ith ;.ri-klv -c. r...
r- o . . . . . .
.\ra rlpn .


Stirr
No





2




2


I


'it


Nilt ro-
mrv Pro- Fat. ;C(rude gIn-
icr t.in. fiber. frecex-
Pr r I tracl.

Per it. Per i'( Prr (t Perrl. Pf'r cl Per ct.


Or-
ganie
matter.


Per ct.


;,l.. 4 21. 46 40. 1' 5A. 1t 35.0SO 75.00 61.57
.I, Z7 41 "? '. 5 ., (5..'. i 42.51 80.36 70.34

. 1. 311 J-2.31 4%. 7. 1 :i. 16 77.73 65.96

u. 4#, J'l. (3 71 3. 9 1.;. 44.28 77.97 73.60
C'. 17 3'l.0 ;0 2. .t 1 1 I 44.05 77.97 74. 15

2.', 39.04 73 4. '1.4-1i I 44.17 77.97 73.88

,. 4.43 4-3 K3 t.99 44.91 42.49 b8.15 57.87
3-.33 31.75 t5. 12 30 '17 3IS 20 71.52 57.63
*- 2 3, u. 5.t,. ) :37. '44 40 35 1i9. S4 57.75

3'1. j.] 3k.9u0 -9.76 21'. 54 26. 5 57 04 42.24
PM. 41 O. .t9 0iu. f5 5,3 2.28 37. 29 7S.65 64.38

I ".SA '9.75 1;.21 '1.41 .31.97 7. R5 53.31


i 1. J. .',7.67


I 0. -'.1
;57 U0
*i.'. 90


:2.h4 'J9 16 4".93


11].'40 77.00 .4. 00
.SA 001 I S. '10 4%. 11)

3'.."0 72. () 51 010


l.'. h4 51 4b 7..3.



1. 441 ihl. 49 1 7'..52
."k. 12". Cf. II ..1
".,5 6..41 i 75.l4
W' 03 4. 950 7t.. 70
t6jj i1; 41). '- 7(. i (


3.i. 'll 3s. UO 96. 10)
-"' 00 *.I00 L ,,.3. -5

7.. 70 -'.. 70 S. 40


72 A4 47.42 77 51
7r,. A. 7 b7. 2"2 fV ',9

74 HI. 57. 32 73.70


49 l.J
43 30

46 00


72. S9 ... ..


71.80 ....
64.00

9. 20'.


35. NS .57 57 71.86 ........
i

'l). 00 46. lut 75.31 1 ......
31j.3 39 )0.44 71.99 .
31.65 50.63 75.24 .......
.%0.57 5. 67 71.S0.


10l3.20 1In. (0t 71.00 87.00
S.. m 190.50 43. ) 69.10

9.1 .30 55 50 60.60 76.10


102.7 37.04 61.8 3 75.09
104.h 34.0b 72.71 77.28

103.7 35.55 6S. 77 76. 19


*i ThX digptinon c'i-fTit-ieil < or.t,iinl.'i from steer No I that wa ferd a ration of prnikly pear and alfalfa
ar- all P id'ently t0o in \I\ nrit. hoilil not be usel in Ih(- prepare tion of rations ironm i trier prickly pea r.
allalfa. or the nmixerd fipit
b Bulletin 77, OUfficeol fxieriment Stations.. Invited States Department of Agriculture.


I








SUMMARY OF THE FIVE DIGESTION EXPERIMENTS.


TABLE 15.- Daily ration.s' fed d,,rinq the fl di;,e.-tion 1erioWd. and a maintenance ration
for ea'h steer ralchltited from IIvf/f'sft'Iieg stidarId for oxen at rest in stalls.
STEER NO. I.


[ 1igi-I 0 l4 organic matter.


, ry Protein.I Carbo- Fat.


Nutri-
Total tive
nutri- ratio.
ents.


1........ Prickly pear iOpf uttint lind- l'uu t,
cmern ..... ....... 13.84
2. ...... Prickly pear (0. Lju i ........ 6.64
3. .. Prickly pear anl alfalIfai ....... 12.99
4........ Prickly pear aiitl r'-trini-seed
meal ...... 14. 14
5 ......... A lfalfa ..... .. . 14. I1
Maintenance ration ........ 15.1(


I' raild, I'ua ndJ
0.42 7.44
.11 3.57
35 6.48


/ 'o nil ,.
0.13
.08
.11


1.(68 6. 13 .62
1.31 5.98 .11
. 60 6.90 .13


Pkound].,
8.00
3.76
6.94


1:18.23
1:33.50
1:19.13


STEER NO. 2.


Prickly pr-ar ,0.punin lind-
tfamt r ..... .. .....
Prickly pear tO Ia, ,;' ....
Prickly pearan.l aItil .......f
Prickly pear an-n i otirtn-seed


meal ......
A llalfit ....... .
Mainrteni nap ration.


12.98
9.36
16.44


...... 17.35
.... 14.23
16.70


0.40 6.98
.16 5.02
. 56 8.93


0.13 7.50
.11 5.29
.17 9.66


1.75 8.09 .68 10.52
1.32 5.98 .11 7.40
.67 7. 5 .14 8.43


TABLE 16 IW'ight ,f .'f;td 'erten,feces and urine excreted, and water drunk ',i,,;rii the five
digestion periods.


\\cighlt of lr'.e1 for \i' vr,ca %%eight of
iedilvy'. it el per day.

Grams. Pounds. Grams. Pounds.

Prickly prLjriOpInnt h' ind-
heimrrir ........ ... 'l.i 413.63 46,884.75. 103.41
Prick I, ptrk0.1, ad, aiit, ri) 17',.tl4 395.48 44,828.5 98.87
Prickly pearO l.is"') ..... 121,322 267.58 2,426.44 53.52
Prickly pear (0. I-f .. w th 360.89 32,726 72.18


Prickly pear.
Alfalfa .
Total ..


Prickly pear ...
2 1 Alfalfa . ....
S Total...
Pncidy pear.... .
Cotton-seed meal ..
Total ..
'(Prickly pear.. ..
2 JCotton-seed meal....


. !5, 5U 21i0. I', 1 i',
10,205 1 2" l 2.041
105,l .i 2I .l 2 1 ,1".


Weight of feces for
five days.

Grams. Pounds.


62,766 138.43
58,591 129.23
20,293 44.75
38,896 85.79


42. If .
I 4 5A

41;. htj |, i,..!5"


13') 71


.. ... I_ _- _. I ...- - - -- - -- - -
129,Y2i7 '07' W;i,." 4 57 IN
I 10,702 23.60 2,1i1 4 4.72 .......... ...........
140, 32 309.49 28,065.8 61.90 73,415 162.07
TI
54, VA18 l6; 3t, Itr.,.'; 5 17.' A.4. .6. .C.
'10,845 23.92 2,169.0 4.78...................
.. 210.2s 'I 1,1.t. 42' 05 54,605 120.43
106. 4 235. 21 ,21,329 0 47 4.......
11,31S 24.96 2,263.6 4.99 .......... ..........


S Total..... .... 117,963 I 260 17 12.3,592 6 52.03 75,155 165.76

1 Alfalfa. .... .... .... '339 9 2 4 .44.72 t79'J4 5 l4:l.,1l4 62,SK) 138 51
2 Alfala ... .. .. .'.140,050 750.0 68,010.0 150.0 81,190 179.07


a This experiment lasted for a period of four days only.


Experi- I
meant
No. I


8.43 1: 4.49
7.40 1: 4.75
7.66 1:12


I..



3.
4.

5.


1:18.23
1:33.04
1:16.65

1: 5.52
1: 4.74
1:12


Ex-
pert- Sleer
meant No
No.






I i"i
l


I
4

4

9
0







34 DIGESTIBILITY OF PRICKLY PEAR BY CATTLE.

TABLE 16.-Weight of feed eatin, feecs and urine ercretled, and water drunk during the five
digestion periods-Continued.


Feed.


PrieLly pear i Opuntia
hirmenr i ..... .
Pncldy pear O.i;ndht
Prickly pear 0 1mv:
lPrirkly pear O lzr'i


Average weight of Weight of urine for
leces per day. five days.

Grams. Pounds. Grams Pounds.

ilind-
....... 15,691 5 34.61 51,9S1 114. 65
rimeri) 14,647.75 32.31 3%,915 85.83
?0 .... 4,058.6 8.95 26,874 59.27
0... 7,779.2 17. 16 50.84S 112 15


Average weight of
urine per day.

Grams. Pounds.


12,995.2
9,728.75
5,374.8
10,160. 6


28.66
21.46
11.85
22.43


i ['n c k ly p ea r .... ..... . ... ..... .........
A lfa lfa . . . . . . .. . I I..... ...
Total 2,67; 27.94 31,7u 69.92 I 6,340 13.98
Prickli pear ....... ..... .. .. ... . .. . . . ....... ...
2 A lfa lfa . . .. . . . . . . . . . . . . . . .
Total .. 14.697 J.T 41, 422,22 93.12 8,444.4 18.62
Pric k pa r . ........ ...................... ....... .................


Total .... ...... 10.921 24 09' 2 75 63.91 i 5,795 12.78

tnP ric kl v pe r .... .... .......... ..........
C o t t . a ... .. . ..... .. I T e .
Total.............15.0.11 I 33 15 37,525 82.76 7,505 16.55
I Allalfd ....... .. ..... 25 27.70 44,7M5 98.,77 8,959 19.75
l2 .flfa .... .. .. ....... 116,2.38 3.81 43,910 !) .84 8,792 19.37
I


Ex-
peri- Steer
meant No,
No.

SI Pr.i'kl pear O0pu
2 Prickly pear iO. I
I 1 Pricklv pear O. 1
2 Prickly ptar .O.1
Prickly pear....
SAlfalfa .....
Total. .


I,


7I


SPrickly pear.
2 Alfalfa ... ....
STotal..

Pricklv pear.. .
SCott-tin- sed meal. .
I Total..
J Prickly pear ..
2 Cotton-seed meal. .
S Total. .
I Alfalfa..
2 Alfalfa ...


Weight of water Average weight of
drunk for five days. water per day.
ed. ______________
SGrams. Pounds. Grami Pounds.

ni, lhrdhfimeri... None. None. None. None.
dhri mfrn.......... None None. None. None.
i.. 17.225 i 37.99 ; 3.445 7.60
S..... ...... .... 12,275 27.07 i 2,4.55 5.41



41,263 91 01 8,252 6 I 18.2



43,240 95.37 8,648 1 19 07
-- ,,,
... ... .. ..... '.... . .. . .

S 66,700 147.11 13,340 29.42
. . . . . . . . . .. . . . . . . . . . . . . . .
... .. . . . . . . . . . . . . . . I . . . . . .

.. ........ ..... 83.475 I 184.11 16.695 36.82
...... 106,480 234.86 1 21,296 46.97
110,980 244.77 22,196 48.95


a This experiment lasted for a period of four days only.


Ex-
peri- Steer
ment No.
No.






GAIN OR LOSS OF NITROGEN.


INCOME AND OUTGO OF NITROGEN.
In Table 17 is given the income and outgo of nitrogen for both
steers during the five digestion periods. The gain or loss of nitrogen
is the difference between the amount taken into the animal as food
and the sum of that which is excreted in the feces and urine.
It is interesting to note that in the first digestion period, when the
steers were fed prickly pear (Opuntia lindheimeri) alone which had a
nutritive ratio of 1 to 18.23, they each gained nearly 1 pound of pro-
teids in the four days. Steer No. 1, for example, ate 1,322.S grams
(2.9 pounds) of protein and gained 453.1 grams (1 pound) or 34.26
per cent.
Prickly pear alone was the ration also for the second period, but in
this expert iment a different species was used, as well as different steers,
and the latter were fat from a previous grain ration and not accus-
tomed to eating prickly pear. Analysis shows that the feed from
this species of prickly pear has about 1 per cent less protein than the
species fed in the first period. The steers ate only about half the
ration eaten by the steers for the first period and digested about 18
per cent less of the protein. As a consequence the nutritive ratio in
this feed was 1 to 33 for both steers, and each lost over one-half pound
of protein, or nearly 50 per cent of that eaten during their five-day
digestion period. Steer No. 1, for example, consumed 99.2 grams
and excreted 146.1 grams of nitrogen in the five (lays, making a loss
of 293.1 grams (0.65 pound) of protein, or 47.28 per cent. In the
third digestion period steer No. 1 ate 42.16 pounds of prickly pear and
4.5 pounds of alfalfa daily, while steer No. 2 ate 57.18 pounds and
4.72 pounds of alfalfa. Something went wrong in this experiment
with either steer No. 1 or our analyses, we can not say which, although
fairly closely agreeing duplicate determinations were secured in all
the analyses. Table 17 shows a low'digestion coefficient by this steer
for all the nutrients. This animal consumed 312.4 grams of nitrogen
for the five days, and excreted 346.5 grams, making a loss of 213.1
grams of protein, or 10.9 per cent of the nitrogen consumed. There
was excreted in the urine 51.76 per cent, hbile with steer No. 2, on
practically the same ration, only 28.16 per cent of the nitrogen was in
the urine.
The results obtained with steer No. 2 were more satisfactory
throughout. lie showed a normal digestion coefficient for all the
nutrients, but it was hardly enough for the proteids to make a theo-
retical maintenance ration for him; yet we find a daily gain in Table
17 of 127.6 grams of this nutrient.
There was a quite uniform gain of nitrogen for both steers during
the fourth digestion period in which prickly pear and cotton-seed
meal composed the ration. The gain for steer No. 1 amounted to
30.46 per cent, and for steer No. 2, 23.07 per cent.







DIGESTIBILITY OF PRICKLY PEAR BY CATTLE.


Fifteen poUnds cif alfalfa per dlay was the ration for both steers
during the fifth period. The digestion coefficient for the two was
close enough to make a nutritive ratio for both (of I to 4.75.
From Table 15 it may be seen that steer No. 1 digested or retained
in his system 1.31 pounds, and No. 2, 1.32 pounds of protein during
this period. According to Wolff's standard for oxen at rest in stalls
these figures are 0.71 pound for steer No. 1 and 0.65 pound for steer
No. 2 in excess of the amount required for maintenance; yet we find
that during the five days steer No. I gained only 302.5 grams (0.66
pound) of protein, andi steer No,. 2 actually lost 222.5 grams (0.5
pound). Why there should he such a slight gain of protein for steer
No. 1 and a loss for No. 2 when the proteins actually digested by
both were far in excess o-f the estimatedil amount required we are at
a loss to say. It may be explained, however, by the supposition
that because uof the narrow nutritive ratio of the feed neither steer
hadl a maintenance ration of nonpriteids, and to supply the necessary
energ- their bodies broke (Iown the proteins andti used the nonni-
trogenous part of the molecule, excreting the nitrogenous portion
produced from the cleavage through the kidneys. That such is the
case would seem to be shown by the fact that steer No. 2, for exam-
ple, in consuming 727.13 gramins (1.6 pounds) f nitrogen excreted
509.4 grams (1.1 poutnd.s,) or 70.)1 per cent in the urine.

T HliE 17.-ln'unir, and oliqo of nutroqf'n ririn.i the .I, dliqrgstion periods.

Ex- irr Nrgn Nirng Ttal Tial Nitrogen
men[ n'trurgen nrirogen igain. +
men No. iii iiriii n inx eIr i nxtrried. Palen. loss. -)
Nt, I


I I'rrklyv Iriair I O.iuritii hinIlhfni i, . .
.2J l'ritklv p'air 0.fr. ,r i
I 1'rickly ppar (0. en.ilmniinnii nr urlo- I
d .ia anl alfalla ......
1 Prickly p.ar i I frntI rinijnn, ryilo,- I.
d ia tl idi (ii ii -'-"J rilral . ..
Alfalfi . .


Ex-]
pern.
Nor I
NO


1 F'rickly pear i Opinrdu It'ndhimntri,..
F Pri kly pear I. Ix is ... ..
3 Prickly pear I(0. cnqulmannii rycloidt I
and alfalfa . .......... . 1
4 Pnckly pear 1tO ngoeluiannnu citloidfa i
i and ol lrjon-seed n'raL ..... ..........
5 AIaLfa .a.......... ...... .......


Gnu n.e
47 I
N. 0
121 ",
lill 7
It' ll
4,111
4.'I .7-
4.'Y) 0
.Ip 4


Gra
S,



24.
24
Y.


l, erI l'rI-AlPli
NP i 1,i. +-
No ain. +
NoI


Gram.
+ 453 1
+ 41. I
- 2.'43
- i5 0
- J.lcs
213. I
+ b3S1
+1.551 9
+ 1. 2t2 5
+ 30-2.5
- 222.5


Msi. Gramrn Grams Grams.
St; I :IQ I 21?1.6 + 72.5
4.4 1:11 .) 19S.4 + 66.9
03 I 141 I [t.2 46.9
1 7 21M.2 140 0 63.2
'4 :t4; | .412.4 34.1
..1 I.5t. 2 35&.3 +102.1
; 7 J; M 1, 3.1 +248.3
12 2 07.1.7 S75 7 +202.0
Ii, 7 71, ;24.9 I + 48.4
,." 7;t.6 7'. .I 35.6


N Irogen Excreted Excreted
igin. +; nitrogen nitrogen
lu.m.s. I. in fetes. in urine.

Per cinl. Petr ment. Per cent.
+34. ?t, 40 43 24.82
+33 72 42.54 23.74
-47 228 f0 58 86.69
-45 14 ,58 35 8679
I0 92 59.15 51.76
+28.50 4334 28.16
+30 46 25.47 54.09
+23 07 ..... .. 49.16
+ i68 34.00 59.32
4.89 34.88 70.01
II






SITMMARY OF RESI'LTS.


CONCLUSIONS.
(1) The average digestibility of the nutrients of prickly pear as
determined in the first experiment where Ompuntia lindheimeri was
used were: Dry matter, 6,5.S6 per cent; ash, 33.6, per cent; pro-
tein, 57.47 per cent; fat, 6S.3S per cent; crude fiber, 41.32 per cent;
nitrogen-free extract, 81.78 per cent.
In the second experiment where the variety 0. 1:>ri.? was used
the coefficient., of digestion were: Dry matter, 63.96 per cent; ash,
35.81 per cent; protein, 40.87 per cent; fat, 69.02 per cent; crude
fiber, 53.A9 per cent; nitrogen-free extract, 78.95 per cent.
In general these results would perhaps show a somewhat low
coefficient for protein, a decidedly low coefficient for ash, but a
very high coefficient for the nitrogen-free extract. The total digest-
ible nutrients are about equal to those of immature green corn fodder.
(2) Our experiments seem to show that when prickly pear is fed
with cured fodders or grains the digestibility of both is increased.
For this reason prickly pear has a gn- iater food value than is shown
by its analysis and digestion coefficients.
(3) The nutritive ratio, i. e., the ratio of proteins to carbohy-
drates, is very wide for this feed, and in feeding it to all classes of
animals, for whatever purpose, much better results should be obtained
when it is fed with some substance of a high protein content.
(4) While the digestibility of the ash was apparently small, as
noted above, yet the large amount of ash contained in these plants
caused more ash to be assimilated from a ration equivalent to 15
pounds of dry matter than is ordinarily assimilated from an equal
ration of alfalfa, which has a higher coefficient of digestion for its ash.
(5) The steers seldom drank water when fed prickly pear alone.
In fact, in feeding a ration of 100 pounds of this feed per day the
animals obtained from the feed over 8 gallons of water, which is
more than was usually drunk by them when fed cured fodders alone.
(6) While no digestion experiments were made with any of the
cacti other than prickly pear, the digestion coefficients of the latter
could probably be safely used for all oithlir members of this family,
since their composition and other characteristics are similar.
(7) It may be seen that both steers gained proteids during the
first experiment, although both ate a smaller quantity of dry matter
which contained less proteids than are required according to Wolff's
standard ration for oxen of their weight at rest in stalls.
In the second experiment both animals lost proteids, but here
steer No. I ate less than half of what was eaten by steer No. 1 in
the first experiment, and steer No. 2 ate over 3 pounds less than
steer No. 2 of experiment XNo. 1.






3S DIGESTIBILITY OF PRICKLY PEAR BY CATTLE.

(8) Animals scour quite badly when fed prickly pear alone; besides,
other feeds are needed to supply the proper amount of proteids;
and for these reasons it is better not to feed it alone.
A ration for a 1,000-pound milch cow of 50 pounds of prickly
pear, 10 pounds of wheat bran. and 10 pounds of alfalfa would
fur'ish about the correct theoretical amount of nutrients, in which
the ratio of proteids to carbohydrates would be I to 5.46.

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