TEXAS AGRICULTURAL EXPERIMENT STATION

A B. CONNER, DIRECTOR,
College Station, Texas

BULLETIN NO. 632 OCTOBER 1943

FRODUCTIVE ENERGY OF CERTAIN FEEDS
AS MEASURED BY PRODUCTION OF FAT
AND FLESH BY GROWING RATS

G. S. FRAPS

Division of Chemistry

 

AGRICULTURAL AND MECHANICAL COLLEGE 0F TEXAS
T. O. WALTON, President

B36—543—4M—L180

 

Previous work with chickens showed that the energy values of feeds
were very nearly in proportion to the digestible nutrients. Experiments
were made with a. different kind of animal—white rats-—to see how the
eniergy was utilized by them.

Beans, casein, cottonseed oil, kafir, oatmeal, starch, wheat flour, wheat
bran, wheat gray shorts and yeast were studied. The gains of energy
were ascertained by analysis of thle rats for protein and fat.

Differences in the energy values of different kinds of feeds were due
chiefly to differences in digestibility and to a much less exflent to dif-
ferences in the utilization of the digested nutrients.

Rats gained less than chickens during the period of the experiment,
used larger percentages of the food for maintenance and smaller per-
centages for storage of fat and flesh. In spite of these differences, the
energy values of the digested nutrients as measurled by rats were nearly
the same as when measured by means of chickens. ‘

OONTEN TS

Page
Introduction _--_ 5
Procedure 5
Details and data of the work 8
Productive energy of rations- 14
Productive energy of feeds 20
Net energy determined elsewhere 20
Comparison of rats and chickens 21
Retention of the protein 24
Acknowledgment 24
Summary 24
References 26

 

PRODUCTIVE ENERGY OF CERTAIN FEEDS AS
MEASURED BY PRODUCTION OF FAT
AND FLESH BY GROWING RATS _

By G. S. Maps, Chief, Division of Ohemistry

Comparisons of the energy values of a number of feeds have been
made by measuring the production of fat and flesh by growing chickens
(7, 9, 10). These investigations have shown that while the energy values
of different kinds of feeds may be widely different, the energy value of
equal quantities of digestible nutrients as a rule are fairly uniform.
It is desirable to know whether or not other animals utilize energy of
feed to the same extent as chickens. For this reason comparisons of the
energy values of feeds with corn meal have been made with growing
rats similar to those made with chickens, the results of which are pre-
sented here.

Procedure

The procedure used is similar to that used for chickens (10). The
feeds to be tested were compared with corn meal fed in standard rations.
Rats were selected soon after weaning and distributed in 5 groups
as nearly equal in weight, sex and otherwise as possible. The rats of
one group were analyzed at once and the four others put upon the
experimental rations. The number of rats desired could not all be
secured at the same time, but they were fed in similar groups“ and
except for experiments A, D and B, for the same number of days. The
rats were fed individually in separate cages, weighed weekly, and killed
at the end of the period, usually 28 or 35 days. The intestinal contents
were removed and in most of the tests the rat was placed in a closed
fruit jar, heated at 15 pounds pressure for three hours in an autoclave,
allowed to cool overnight and ground in a food chopper with the addition
of 3% filter paper to absorb the liquids. Protein (N >< 6.25) was deter-
mined on 3.5 gram samples by the Kjeldahl-Gunning method. Fat was
determined on 4 gram portions by extracting with ether after drying
under reduced pressure at 100° C., and grinding in a mortar. The
energy content was calculated by the use of the factor 5.60 calories
per gram for protein and 9.35 for fat (5), which previous work with
chickens has shown to give the same number of calories as combustion
in a bomb calorimeter.

In Experiment A, some of the rats were prepared by drying in a
vacuum desiccator over sulphuric acid, extracting with ether, and drying
the residue. With use of a bomb calorimeter the heaft of combustion
was determined in the ether extract and in the dried ground residue.
The method was found .to be too laborious, s0 that the procedure was
abandoned and analysis made of the rats ground up as described above.
Analyses were made of the rats in some of the first experiments without

TGbIQ 1.

Percentages of Constituents of rations used in Exp. A. 0. and 2B.

Corn
Meal

Exp. A

Kafir
Exp. A

Wheat
Gray
Shorts

Exp. A

Corn
Meal

Exp. O

Wheat
Bran

Exp. O

Oat
Meal

Exp. O

Oorn
Meal

Exp. B

Graham
Flour

Exp. B

Salt mixture ________________ _.1._
Sodium chloride _______________ __
God liver oil __________________ _-
Brewers yeast _________________ __
Irradiated yeast ______________ __
G‘asein____‘_ ____________________ __
Cottonseed 0-il ________________ --
Corn meal ____________________ __
Kaflr __________________________ _-

Wheat gray shorts ___________ __'

Wheat bran and s‘creenings____
Wheat bran (breakfast io-od)-
Starch _________________________ __
Oat meal ______________________ _.
Navy beans, cooked __________ _-
Graham flour _________________ __
Wheat flour ___________________ __

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PRODUCTIVE ENERGY OF‘ CERTAIN FEEDS 7

previous cooking. There isno reason to think the results were difierent
but the cooked rats were more easily prepared for analysis.

Rats in Experiments A and O were fed from 42 to 68 days, those in p

set B from 60 to 68 days, in such a. way as to equalize the rats on each
ration and have the same number of rats on all 4 rations fed the same
number of days. In the other experiments, all the rats in the same
experiment were fed the same number of days, either 28 or 35. Metabo-

‘rable 2. Percentage composition of feeds and their effective 012M110

 

 

constituents
Effec-
Nitro~ tive_
Labora- gen 012M110

tory Ether Crude tree consti-
Number Name oi Feed Protein extract fiber extract Water Ash tuents
43636 Beans‘, navy (cooked)- 24.07 1.70 5.50 61.77 2.93 4.03 89.67
51950 Casein _________ __,_____ 85.83 1.56 .14 1.83 9.42 3.22 89.17
52124 Casein ______________ __ 83.05 .43 .17 3.28 9.01 4.06 * 87-30
59109 Casein ______________ -1 81.31 1.37 .14. 2.2a 10.33 4.57 86-67
60164 Casein _______________ __ 82.2.5 1.95 .19 2.55 9.89 4.07 89-29
60672 Casein- .............. _- 82.45 1.78 .22 2.231 9-20 4-12 88569
62943 Casein _______________ ..- 82.33 1.46 .23 1.92 10.57 3-49 817-54
63630 Casein- ______________ __ 80.94 .14 .14 5.651 8.87 4.26 80-91
43653 Corn meal ........... __ 9.84 8.62 1.34 75.45 8.50 1-25 93-44
51960 10.70 2.81 1.06 74.35 9.79 1.29 91.37
52141 10.50 2.96 1.02 74.28 9.92 1.32 91.44
62938 10.20 4.34 1.48 71.18 11.49 1.31 91.15
63631 10.05 4.20 1.31 72.00 11.22 1.22 91.50
4%.’) 11.08 5.93 1.68 69.21 10.54 1.61 93.63
5%~86 9.50 3.36 1.08 73.39 11.71 .96 90.45
60168 9.92 4.46‘ 1.37 71.4-4 11.47 1.34 91.40
66676 9.81 4.16 1.23 70.71 12.90 1.19 89.88
51% Flour, patent- ______ -- 12.18 .79 .22 74.40 11.90 .56 88.31
44490 Flour, white ......... -- 10.38 .98 .39 75.50 12.27 .48 88-09
44486 Flour, whole wheat_-- 12.59 1.90 2.28 69.50 12.01 1.72 86.37
43057 Kaflr, white- ________ __ 12.04 2.57 1.817 72.42 9.88 1.22 90.24
43609 Oatmeal _____________ __ 15.46 5.81 1.56 65.62 9.78 1.77 94.15
5212a Starch, corn ......... __ . .23 .17 i 28.46 10.45 .11 89.56
51952 Starch, corn _________ __ .64 0 .14 88.28 10.85 .09 88.92
60165 Starch, corn _________ ..- .56 .14 .18 88.36 10.71 .06 89.23
60673 Starch, .65 .05 .23 86.16 12.81 .10 86.92
59687 Starch, .27 .08 .10 87.70 11.76 .09 88.15
62942 Starch, .59 .18 .17 86.20 12.78 .08 87.20
63629 Starch, corn _________ -_ .43 .04 .17 87.08 12.23 .05 87.60
44488’ Wheat bran, Kelloggs- 12.59 2.03 9.10 62.13 6.14 7.95 79.29
43635 Wheat bran, Keiloggs- 12.86 2.21 8.97 68.76 4.30 7.90 81.59
430E Wheat bran___ _______ -- 15.70 4.35 10.79 54.64 7.97 6.55 80.13
51961 Wheat bran- ________ -_ 18.68 4.28 10.17 50.88 9.15 6.84 79.19
59669 Wheat bran _________ __ 18.36 4.17‘ 9.41 50.47 11.73 5286 78.21
62941 Wheat bran _________ __ 19.48 3.25 10.09 49.72 11.04 6.42 76.51
43054 Wheat gray shorts____ 18.16 4.26 5.42 57.98 10.16 4.07 85.68
51962 Wheat gray shorts_-__ 19.15 4.30 7.08 55.74 8.88 4.85 84.57
62999 Wheat graylshorts___'_ 15.21 2.87 5.91 59.05 10.81 6.15 821,72
58608 Yeast, brewers ______ _- 43.92 1.09 4.90 37.69 4.48 7.92 84.06
60166 Yeast, brewers ______ __ 53.50 .50 2.94 27.21 7.35 8.50 81.84
60674 Yeast, brewers- _____ __ 52.43 .69 6.72 27.19 4.93 8.04 81.17
62940 Yeast, brewers- ..... -- 51.19 .97 .37 35.54 4.44 7.49 88.91
63627 Yeast, brewers ______ -_ 51.18 .81 2.80 34.40 3.57 7.24 87.40
51951 Yeast, irradiated ____ __ 47.78 .75 1.02 34.52 7.64 8.29 83.99
59685 Yeast, irradiated .... -_ 47.42 1.22 .65 36.46 7.02 7.23 86.63
60167 Yeast, irradiated ____ -.. 47.70 1.16 1.17 35.89 6.92 7.16 86.20
60675 Yeast, irradiated ____ __ 48.25 1.22 6.37 30.86 6.86 61.94 81.86
62944 Yeast, irradiated ____ __ 48.46 1.37 2.02 35.97 5.28 6.90 87.51
63628 Yeast, irradiated ____ _- 49.47 1.31 3.60 33.90 4.74 6.98 86.32
51954 Yeast, non-irradiated- 47.25 1.19 1.08 34.97 7.57 7.94 84.90

8 BULLETIN NO. 632, TEXAS AGRICULTURAL EXPERIMENT STATION

lizable energy was calculated by use of the factor 4.2 cal. per gram for
the effective digestible nutrients as was done with chickens (10, 11).

Details and Data of the Work

The rations used in Experiments A, O and B are given in Table 1 and
were planned to furnish approximately equal amounts of productive
energy. The standard corn meal ration used in the other experiments
was composed of 50 per cent corn meal, 20 per cent casein, 19.8 per cent
starch, 5.0 per cent brewers yeast, one per cent each of irradiated yeast
and cottonseed oil, tricalcium phosphate, calcium carbonate, and salt,
.02 per cent cod liver oil. The quantities of the test feeds which replaced
the corn meal are shown in Table 7. Chemical analyses were made 0f
all the feeds and also of the mixed rations. The percentage composition
of the feeds and their effective organic constituents are given in Table 2.
As in previous work, the percentage of effective organic constituents is
the percentage of protein plus the percentage of nitrogen-free extract
plus the percentage of fat multiplied by 2.25.

Digestion experiments with rats were made 0n all the rations except
those used in Experiments A, O, and B, usually two digestion experi-
ments being made on each ration. The effective digestible nutrients
of each ration as calculated from the average of the digestion experi-
ments and the chemical analyses of the rations, are g;ven in Table 7.

The average live Weights, percentage of protein and fat, and calories
per 100 grams of rat, as well as other data, are given in Table 3. The
averages are made from the data for each individual rat. Variations
in fat content of the rats are shown in Table 4. Wide variations are
to be seen, especially with wheat gray shorts in Exp. 9, in which the
fat content of the rats ranged from 6.82 to 22.62 per cent. In spite of
these variations the productive energy calculated from the results, as
shown in Table 8, did not vary widely.‘

Calculation of Maintenance Requirements of the Rats

This work is a comparison of the energy values of other feeds as com-
pared with that of corn meal, but it is necessary to calculate the
maintenance requirements in terms of productive energy used for main-
tenance by the rats in the groups compared.

For the purpose of the comparison, the productive energy of corn
meal and of the standard ration was assumed to be 3.00 calories per
gram of effective digestible constituents. The value used for corn meal
is the same as that found to be correct for chickens (9). From the
work reported on chickens (9) the other constituents of the basal ration‘
appeared to have equal values to those cf corn meal. It is recognized
that these values are assumptions which may not be exactly correct,

but some assumption had to be used in order to make the calculations. _

It is reasonable to suppose that the cells of the body of the ‘rat are not
Widely difierent from those of the chicken, so that differences in the

I

Table 3. Average composition, weight: and. calorie; per 100 gm for rats

l

. I WlLfifteI
No. Live wt. Live wt. Emptywt. % empty prepara-
aver- at start at end at end wt. o1 tion Protein Fat Clal. per
aged gm gm gm live wt. gin ‘ % % 100 gm
1
Exp. 0
Preliminary rats
Calories per 100 gm- ___________________________ -. 155.3

Corn meal rationq ....... -4 _______________________ -_ 6 39.9 136.6 183.4 991.26 130.0 19.59 17.00 269,9
Ke1logg’s bran ration- ______________________________ .. s 39.6 169.5 164.4 90.88 162.0 19.34 16,43 203,5
Oatmeal ration _____________________________________ _. s 39.5 172.5 108.7 97.76 165.1 20.15 14,39 248,0
Cooked navy beans ration __________________________ _- s: 33.7 155.7 191.2 7.00 143.1 19.69 12.32 226,0
Exp. B

Preliminary rats

Calories per 100 gm _____________________________ _. 155.3

Corn meal ration ___________________________________ _- s 41.4 177.9 173.8 97.77 177.1 20,11 15.34 261.9
Graham flour ration_ ______________________________ __ 7 41.5 177.8 174.7 93.16 176.5 20,77 14,56. 253,0
Kelloggks bran ration ............................. _- e 40.0 173.3 170.2 98.15 172.5 19,23 17,94 276,5
Patent flour ration __________________________________ _.‘ 8 41.1 177.7 174-9 98.37 175.6 20.11 16.17 265.0 ‘
Exp. 1 a 1

Preliminary rats ____________________________________ --' 6 40.7 38.7 94.97 391.1 191.6214 9.11 191.2

Calories per 100 gm _____________________________ __ 1721.1

Corn meal ration ____________________________________ _- 6 40.4 153.4 148.5 97.03 146.3 20.067 12.91 234,2
Wheat bran ration ____________ _'_ ___________________ _- 6 40.9 126.6 118.9 99.93 118.0 211.065 6.62 181.2
Wheat gray shorts _________________________________ __ 6 39.9 145.4 138-0 95.00 137.2 20.739 7.92 191.4
Patent flour ration _________________________________ -- ,6 40.3 135.0 1311-1 97.16 130.5 201.860 8.39 1961.5
Exp. 2

Preliminary rats ____________________________________ _- 6 38.7 37.8 97.68 38 3 12.379 9,32 195,8

Calories per 100 gm- ____________________________ __ 191.3 ,

Corn meal ration_____t _____________________________ __ 0 38.8 155.5 150.7 97.00 150.7 20,346 31,34 190,0
Starch ration _______________________________________ -_ 6 39.8 145.1 140.1 90.64 137.2 201.032 11,30 224,0
Casein ration _______________________________________ -_ 6 38.9 141.5 1316.7 96.62 135.1  10,00 20914
Cottonseed oil ration- _____________________________ __ 6 38.5 162.1 1517.5 97.17 158.0 20,275 11,53 223,0
Exp. 3‘

Preliminary rats ..... -. _____________________________ _- 6 30.2 34.1 94.03 31.5 19.010 9,33 139,2

Calories per 100 gm _____________________________ __ 177.9

Corn meal ration ____________________________________ __ 6 38.0 183.31 172.8 94.25 165,1 20,119 12,92 234,7
Dbttonseed oil ration-‘ ........ __- ................... -_ 6 37.8 172.3 162.3 94.16 156,9 20.2.26 19.96 244,1
Wheat bran ration __________________________________ __ 6 37.3 148.1 134.6 90,95 130,2 21,457 9,71 212,2
Uasein ration _______________________________________ _- 5 39.9 152.6 141.1 92.34 135.7 21.465 10,30 2104

SGEIEIJ NIViIfHHO JO LBHEINEI HALLOHCEOELI

Table 3. Avorage composition, weight and calories per 100 gm. for rats-Continued

E
Wt. after
No. Live wt. Live wt. Emptywt. % empty prepara-

aver- at start at end at end wt. of tion Protein Fat C‘al. per w
aged gm gm gm live wt. gm % % 100 gm C;
. b‘
t"
H
Exp. 6 fi
Preliminary rats--- ___ 6 35 8 33.3 92.78 31.1 19.3161 7.54 179.8 Z
Calories per 100 gm- ____________________________ __ 166.8 Z
Corn meal ration ___________________________________ -- 6 35.4 158.7 150,0 94.69 144.4. 20.979 11.64 227.6 o

Starch ration 6 35.7 154 3 147.7 95.74 142.1 20.595 11.65 225.5 '
Casein ration .... -. _________________________________ -_ 6 34.8 14.7 7 133.2 90.55 132.5 21.099 - 10 55 217.7 g

Cottonseed oil ratlon- ------------------- u; _______ -- 6 35.7 162.0 154.0 96.14 148.0 20.540 12. 2281.6 -
Exp. 7 g
Preliminary rats ____________________________________ __ 6 45.7 42.5 92.913 40.5 19.500 10.83 211.6 g
Calories per 100 gm _____________________________ -_ 196.7 m
Corn meal ration _._ 6 46.8 164.8 156.4 94.87 148.7 20.741 11.08 221.0 ‘
Starch ration_ 6 44.9 150.2 142.7 95.15 1351.6 20.407 12.03 227.9 g
Casein ration_- 6 45.9 157.2 147.5 93.84 139.5 21.257 9.84 215.3 .3,
Yeast rati0n____- ___- 6 46.3 151.8 140.5 92.62 134.5 21.163 7 69 191.6 v5
Exp. 9 S:
Preliminary rats -_ 6 .6 35.9 95.68 33.3 19.686 8 41 190.0 1%
Calories per 100 gm- ____________________________ -_ 191.8 <3
Corn meal ration 6 38.4 149.5 144.9 96.95 136.5 21.880 12.04 236.4 E
Wheat gray shorts- 6 38.4 144.3 1.37 2 9'5 14 128.0 21.350 12.64 239.1 t‘
Wheat bran ration 6 37.7 134.6 125.6 93 21 118.1 21.749 8.45 202.1 m
Yeast ration- ___ 6 37.9 136.2 127.5 93.60 120.4 21.923 6.83 187.9 N
*6
Exp. 10 Q
Preliminary rats - o 40.1 38.0 9499 36.5 19.424 6.55 171.2 E

Calories per 100 gm- ............................ __ 162 7

Corn meal ration 6 41 1 152.5 143.0 93.68 134.1 20.744 9.91 198.7 H
10% Cottonseed oil ration _________________________ -_ 6 40 7 155.7 146.8 93.65 138.1 20.877 9.12 203.4 Z
20% Cottonseed oil ration _________________________ -- a 40 s 162.3 151.8 93.69 149.8 20.509 10.95 218.5 '5
30% Cottonseed oil ration _________________________ __ 6 40 2 132.1 121-9 92.40‘ 1151.1 20.050 12.12 226.8 a
Corn meal ration average (9) ..................... -- -_- ___ -_- - - - - - - - - - - - - - - - - - - - - ~- 12-41 ___- p:
D-l
5%

 

 

11

PRODUOTIVE ENERGY OF CERTAIN FEEDS

Table 4. Variations in fat as calculated from individual rats

 

Fat Aver-
age
No. Aver- Maxi- Mini- differ-
Experiment number Aver- age mum mum ence Standard
and name of ration aged % % % % 1191711111011

Experiment 1

Corn meal ration---‘ ...... -- e 12.91 15.70 9.96 2.61 2.9a

Wheat bran ration ________ -- 6 6.62 8.07 5.60 .81 .98

Wheat gray shorts ration_- 6 7.92 10.20 5.83 1.50 1.88

Patent flour ration ........ -- 6 8.39 11.80 6.40 1.23 1.83
Experiment 2

Corn meal ration __________ -_ 6 8.34- 10.10 6.9'7 1.05 1 $8

Starch ration ______________ -- 6 11.80 14.81 8-96 l 1-79 Y 35

Oottonseed oil ration ..... -_ 6 11.58 12.78 10.67 .75 90

Casein ration .............. -- 6 10.00 12.96 7.23 1.67 2 15
Experiment 3

Corn meal ration __________ -- 6 12.92 15.63 9.53 1.49 2.08

Cottonseed oil ration _____ __ 6 18.86 16.94 11.61 1.95 2.27

Wheat bran ration ________ __ 6 9.71 11.13 8.08 88 1.14

Casein ration ______________ __ 5 10.36 11.40 8.37 1.19
Experiment 6

Corn meal‘ ration __________ __ 6 11.64 13.11 9.43 1.37 1 61

Starch ration ______________ __ 6 11.65 13.19 10 13 .82 1 05

Oasein ration ______________ -- 6 10.55 12.84 8 15 1.57 1 98

Oottonseed oil ration____--_ 6 12.01 15.49 7 75 2.20 2 88
Experiment 7

Corn meal ration- ________ __ 6 11.08 13.80 9.04 1 58 2.00

Starch ration"--- 6 12.03 13.40 10.59 92 1.13

Casein ration _____________ _- 6 9.84 11 27 8.29 1 08 1.28

Yeast ration _______________ __ 6 7.69 8 90 6.77 71 .84
Experiment 9

Corn meal ration _________ ___ 6 12.04 13.02 9.75 1.04 1.29

Wheat gray shorts ration" 6 12.64 22.62 6.82 5.15 6.30

Wheat bran ration ........ __ 6 8.45 10.82 6.45 1.85 2.08

Yeast ration _______________ -_ 6 6.86 7.67 5.73 .62 .77
Experiment 10

Corn meal ration __________ -- 6 9.91 11 87 8.12 1.30 1.52

Cottonseed oil ration, 10%-- 6 9.12 10.06 7.78 .61 .84

Cottonseed oil ration, 20%-- 6 10.95 13.88 9.32 1.15 1.65

Olottonseed oil ration, 30%-- 6 12.12 13.39 9.34 1.13 .37
Corn meal ration average (7)__ -_- _____ _____ _ _ _ _ _ _ _ _ __ 1,81

utilization of digested energy may not be wide between th-e two. Any
small differences would be eliminated, since the results are comparative,
the energy used from feeds tested being compared with that used from
corn meal.

As shown in Table 5, the initial energy content of each rat is calcu-
lated from the initial live weight and] the initial energy per gram as
found by analysis of similar rats in the same experiment. The final energy
content is calculated from the final empty weight and final energy
content per gram of the rats. The productive energy consumed in the

l
Table 5. Average data and calculation or maintenance requirements for rate

Z1

 

1
For Maintenance / Eflectiye
, Prod. digesti-
Expen- Average Initial Final Gain Prodenergy energy Total Prod. Prod. ble con-
ment Wt. by energy energy of of ration Ration of feed prod. energy per energy per stituents
Number periods content content energy Gal. per eaten eaten energy period per day per of ration
gm. Gal. Gal. Gal. gm. gm. Gal. Gal. 100 gm. Gal. 100 gm. Gal.
I
O 108.8 61.9 498.6 436.4 2.604 39073 10953 66013 602,5 11,24 ___
A 92.2 57.0 301.0 244.0 2.190 4321.8 995.5 751.5 8109.6 15.94 ___
B 111.8 64.2 4521.7‘ 388.5 21.668 545.4 1570.7 1182.2 1069.5 16.42 _-_-
1 99.0 69.5 347.4 277.9 2.368 291.0 745.0 467.1 471.9 16.85 86 1
2 98.4 74.2 2915.7‘ 221.5 2368 2701.4 692.1 470.6 479.2 17.12 86.2
3 110.0 67.6 403.1 335.5 2.307 359.6 895.4 559.9 512.3 14.64 85.3
6 98.4 59.1 3391.6 282.1 2.359 318.0 811.0 530.5 542.9 15.51 86.0
7 109.1 904.1 346.3 256.1 2.309 272.3 678.0 421.9 3910.0 13.93 84.6
9 106.9 69.8 342.0 272.2 2.532 333.7 844.2 572.1 5399 15.43 85.7
10 100.1 66.8 278.4 211.6 2.557 277.5 707.6 496.0 495.8 17.71 86.1
Aver-
age (10) 103.5 292 e 903.6 15.48

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PRODUCTIVE ENERGYTOF‘ CERTAIN FEEDS 13

standard corn meal ration is the grams of the ration eaten, multiplied
by the productive energy per gram. of the ration, as calculated from
its effective digestible nutrients and a value of 3.0 calories per gram of
effective digestible nutrients. By subtracting the gain of energy of each
rat from the productive energy of the total ration eaten, the productive
energy used for maintenance is secured, since, by definition, the pro-
ductive energy of the ration used for the gain is equal to the gain in
energy of the animal. The total calories used for maintenance are
divided by the weight by periods and multiplied by 100 to give the
calories of productive energy used to maintain 100 grams of rat for the
period of the experiment. The latter result divided by the number of
days, gives the calories of productive energy used for maintenance per
day per 100 grams.

The maintenance requirements are calculated with the use of average
weights by weeks. That is to say, the first and last weight for each week
were averaged to secure the average weight for that week, and the sum
of the average weights for all the Weeks was divided by the number of
weeks to secure the average weight by periods. This method has been
shown with chickens (5) to give more consistent results than the use of
the average of the first and last weight of the entire period, and also,
so far as productive energy is concerned, to give more consistent results
than the use of the surface area. The average productive energy used
for maintenance as given in Table 5 ranges from 11.24 to 17.71 calories,
with an average of 15.48 calories per day per 100 grams. In terms of
metabolizable energy, of which the productive energy is apparently
72 percent, 21.6 calories per day per 100 grams would be used for
maintenance. According to the data of Kibler and Brody (12), female
albino rats weighing 112 gms. used 26.7 calories per day measured by
oxygen consumed and male rats weighing 119 gms. used 24.2 calories
per day for maintenance. The female rats apparently had the same
maintenance requirement for weights of from 112 to 185 grams,
regardless of weight or surface area, while that of male rats decreased
with age, either on a weight basis or a surface basis, up to a weight
of about 200 grams.

The results of Kibler and Brody are apparently higher than those
here given when compared at 100 grams weight, but if compared at
greater weights, they would be the same or lower, depending on the
Weight selected. If average weight is 100 grams in the work presented,

tpart of the time the rats weighed more than 100 grams and part of the

time they weighed less, as can be seen from the average live weights at
the start and at the end given in Table 3.

The maximum, minimum and average calories of productive energy
requirements for maintenance are shown in Table 6. The standard devia-
tion is low (less than 5 per cent) except with experiments 7 and 9,
in which it is appreciably higher, being more than 10 per cent.

14 BULLETIN NO. 632, TEXAS AGRICULTURAL EXPERIMENT STATION

Table 6. Average maintenance requirements 1n productive energy, Calorles
per kilogram per day, calculated from individual rats, with
Standard deviation

l Maintenance requirements,

 

' l Calories per kilogram Standard
Series Number Feed N0. 1 _ _ _ devlfitlml
l Average Maximum‘ Minimum l
I
l 1 ‘
l l ‘
28 days l
1 __________________________ __ 51964 l 168.5 1741.61 158.3 5.6
2_ _________________________ __ 52137 \ 171.2 177.4 161.9 7.0
7_ _________________________ __ 00677 . 139.3 163.3 125.1 15.2
1o_ ________________ __, ______ __ 03632 I 177.1 191.3 I 7.3 9.3
Average (4) ...................... _- l 164.0 177.9 1 155 2 9.3
35 days
___________________________ n] 59688 146.4 157.5 136.9 9.7
6- _________________________ --1 60169 155.1 167.4 144.1 8.9
9 __________________________ __ 62946 ' 154.3 194.6 124.1 23.2
Average (s) ______________________ _- ' 15.1.9 173.2 1 135.0 I 13.9
Average (all) (7) ................ -- 158.9 175.9 ( 145.4 f 11.3
l

I

Productive Energy of Rations

The average data and. results of the calculation of the productive
energy of the rations which were compared with corn meal are given
in Table 7. The energy used for maintenance is calculated by multiply-
ing the average weight by periods of each rat by the average calories
required to maintain 1 gram of rat as found with use of the corn meal
ration for the same experiment as calculated in Table 5. The sum of
the calories for maintenance and for gain of energy gives the total pro-
ductive energy of the quantity of the feed eaten. This sum divided by
the quantity of feed eaten gives the calories of productive energy per
gram of the ration. The productive energy of the ration is given in the
next to last column of Table 7. In Experiments A, O, and B, the four
rats in each comparison were fed the same number of days, but all the
rats in a group were not fed the same number of days. The maintenance
requirements of the rats on the corn meal ration were calculated per day
per 100 grams and from this data the maintenance requirements of the
other rats were calculated for the number of days each was fed.

In securing the values given in Tables 5 and 7, the maintenance

 

requirements and productive energy were first calculated from the data.

for each individual rat and then averaged. The results would be slightly
different had the maintenance requirements or the productive energy
been calculated from the average data.

The average differences from the mean of the productive energy of
the rations, and the standard deviations are given in Table 8. The
standard deviations are comparatively small, being less than 6 per cent
in most 0f the experiments, except in Experiment 10, with refined cotton-
seed oil, in which the variations were appreciably larger.

Table 7. Data. and calculations for average productive energy of rations and. eflective digestible nutrients

Eflvictive
. Prod. digestible
Name of ration Aver. ' Used for For energy nutrients
Lab. No. and percentage of No. Wt. by Initial Final Gain of Ration Mainte- Gain and o1 ration of ration
the important feed Aver- period energy energy energy eaten nance Mainte- Cal. per
Gm. Cal. Cal. C‘ . Gm. Cal. nance per Gm. 100 Gm.

43685 Wheat bran (38-75) _________ __ 8 101.6 01.4 434.4 378.0 407.6 658.6 180.0 2.039 ___ w
43000 Oatmeal (82.0) ______________ -- 8 103.5 01.3 417.5 0500 407-8 668.0 102.8 1.949 ___ w
43636 Cooked navy beans (52.46)__ 8 95.5 60.1 349.8 2891.5» 391.5 616.6 184.0 1.543 ___ Q
44490 Graham flour (72.72) ..... -_.__ 7 120.2 54.5 441.1 370.0 481-0 1260.0 1642.0 2.96s ___ t!
44488 Wheat bran (40.29) _________ __ s 112.9 02,0 474,2 412.2 545.9‘ 1199.6 1011-8 2.941 ___ g
44490 Wheat flour (70.03) _________ __ s 117.8 03,3 407,5 406.7 555.8 1249.2 1652.9 3.013 ___ a
51961 Wheat bran (50.5) __________ __ 6 84.2 70,4- 215,0 144.6 292.3 397.6 542.2 1.858 45 7 1-1
51962 Wheat gray shorts (500)---- 6 911.7 68.7 263.8 195-1 W115‘ 432-6 627-7 2-162 62-3 é
51903 Patent 110111- (50.0)_ ________ __ 6 89,5 00,4 256,0 186.6 257.7 422.2 608.8 2.359 82.2 *
5212a Starch (50.0) _____________ __,__ 0 91.0 74,2 311,1 209.9 254.9 428.6» 000.5 2.521 s40 t; .
52124 Casein (2540) _________________ __ 6 90,0 74,4 283,6 209-2 2142-1 423-8 603-0 2-017 80-5 g 1

Cottonseed 011 (15.0) _______ -- 0 99.4 75.7 351.4 277-7 233-0 408-4 740-1 3-802 200-9 w

Cottonseed 011 (20.0) _______ -- e 105.5 57.2 397.1 380-0 287-5 540-3 870-2 3-017 210-0 i}
591660 Wheat bran (50.0) __________ __ 0 92,1 00,3 200.0 220-8‘ 376-3 471-7 692-0 1-834 47-1
591091 Casein (30.0) ________________ __ 5 94,0 09.2 305,7 230-5 3251.8 481-3 717-8 2-191 79-9 O

Cottonseed oil (20.0) _______ -_ 6 98.8 59.6 249.0 2891.4 292.3 523.4 812.8 2.772 208.3 *5
00165 Starch (50.0) ________________ __ 0 02,4 59,5 330,0 273.7 329.5 400.7 763.4 2-817 84-9 O
50104 Casein (50.0) _________________ __ 0 90.0 58.0 300,2 242.2 000.0 471.1 713.0 2.330 77-8 g
6061731 Starch (501.0) ________________ __ 6 95,9 313,4 325,1 23647 252.6 3741.1 610.8 2-4-17 84-0 ,5
60672 Casein (30.0) ________________ __ e 102,0 90,2 315,3 225.6 260.9 39717 623.4 2-390 80-2 p;
50074 Brewers yeast (30.0) ________ __ 0 101.0 91.1 259.5 177-4 260-8 304.1 571-5 2-100 07-4 g
62939 Wheat gray shorts (50.0)_-_- 6 101.9 69.8 32.5.9 256.1 379.7 550.5 806.6 2.113 61.7
02041 Wheat bran (50.0) __________ __ 0 90.5 09.5 252.1 180.5 2.70.5 487.8 671-0 1-812 47-2 ‘Q
62940 Brewers» yeast (30.0) ________ __ 6 80.8 68.8 2318.0 160.2 293.6 468.5 637.7 2.1614 65.0 m

Cottonseed oil (10.0) _______ __ 6 101.6 66.2 296.3‘ 230.2 271.5 504.1 734.3 2.749 219.4 U

Cottonseed oil (20.0) _______ -_ 6 104.0 66.3 330.6 264.2 250.3 515.8 780.1 3.122 2127.8 (I1

Cottonseed oil (30.0) _______ _- 6 84.0 65.5 274.9 209.5 197.7 416.8 6261.3 3.257 218.5

16 BULLETIN NO. 632, TEXAS AGRIQULIUKAL EXPERIMENT STATION

Tab1e_8. ‘Variations in average productive energy pf rations as calculated
from data from individual rats

Productive energy“
‘ of rations
mpeririient number and names Calories per gram Average Standard
of rations difference deviation
Average Maximum Minimum
Experiment 1
Wheat bran ration .................. -_ 1.86 1.91 1.79 .04 .05
Wheat gray shorts ration ......... __ 2.16 2.36 2.031 .08 .12
Patent flour ration-__-_; __________ -- 2.36 2.49 2.21 .08 .10
Experiment 2
Starch ration ........................ -_ 2.52 2.62 2.44 .05 .0’!
Cottonseed oil ration ______________ ..- 3.20 3.25 3.16 .03 .03
Casein ration _______________________ __ 2.62 2.68 2.45 06 .09
Experfmcnt 3' ‘
Cottonseed oil ration ______________ -_ 3.02 3.22 2.76 14 .18
Wheat bran ration _________________ _- 1.83 1.95 1.77 05 .07
Casein ration _______________________ -_ 2.19 2.33 2.04 12 I .14
Experiment 6 i
Starch ration ....................... _- 2.32 2.59 2.09 .15 i .19
Casein ration _______________________ _. 2.33 2.41 2.25 .05 ‘ .06
Cottonseed oil ration ______________ _. 2.77 2.96 2.61 .11 l .14
Experiment 7 .
Starch ration _______________________ __ 2 42 2.52 2.29 .06 V. 08
Casein ratio-n; _____________________ -- 2 39 2.49 2.30 .04 i 06
Yeast ration _________________________ __ 2 17 2.20 2.05 .08 j 10
Experiment 9 '
Wheat gray shorts ration _________ __ 2 11 2.23 1 95 12 J3
Wheat bran ration _________________ -_ 1 81 1.87 1 74 04 ,05
Yeast ration ________________________ _- 2 16 2.30 2 05 0s _10
Experiment 10 ‘
10% Cottonseed oil ration _________ _- 2.75 3.05 2x09 33 i 3,4
20% Cottonseed oil ration _________ -_ 3.12 3.57 2.9a _16 i 13
30% Cottonseed oil ration _________ __ 3.26 4.00 2.71 as i A3
i

Calculation of the Productive Energy of the Feeds

The prcductive energy of the individual feeds compared with corn
meal was calculated by the method previously described (9, 10) except
for Experiments O, A and B. The grams of effective digestible nutrients
of the corn meal ration, multiplied by 3.0 gives its. calories of productive
energy. The effective digestible constituents of the corn meal multiplied
by 3.00 gives its calories of productive energy. The difference between
the productive energy value of 1 gram of sthe corn meal ration-and of
the ration to be compared gives the effect of substitution of the feed
studied. This difference added to the productive energy of the corn
meal replaced gives the productive energy of the quantity of the feed
used. The productive energies of the effective organic constituents and
of the effective digestible constituents were then calculated from the
values for the productive energy

In Experiments A, O and B, however, the calculation was slightly
different, since the rations were made up to What then appeared to be
equal productive energy. Productive energy values per gram of feed

 

 

Table 9. Productive energy in terms of feed, eflective organic constituents, efiective digestible nutrients and
~ metabollzable energy
Productive energy
Effective Efiec< Metabo-
Per organic tive lizable Total Efiec- Efiec- Rankwith In per-
Name and laboratory Exp. cent » con- digestible energy feed tive tive effective centage of
number of feed No. of i stituents nutrients Gal. . organic digestible digestible metaboliz—
ration ; p431‘ cent, p31‘ cent per 100 gm. per 100 gm. consti- nutrients nutrients able
tuents . of corn energy
per 100 gm. per 100 gm. meal as 100
Beans, navy, cooked
43636- ___________________ -- 0 __ 89.7 75.4 317.0 165 184 219 73 52.0
Casein
52124 _____________________ _ _ 2 25» 87 . 3 80 . 5 33S . 1 283 324 352 117 83 . 7
59109 _________ _- 3 30 86.7 79x9 336.0 156 180 195 65 461.0
601644- __________ __ 6 30' 89. 3 77 . 3 325. 0 181 203 2324 78 55. 7
60672- __________________ __ 7 30 88.7 80.2  221 249 276 92 66.0
Average (4)_-__ ______________________ "l 88.0 79.5 334.0 2'10 239 264s 88 62.9
Oorn meal (Standard)

0* __ 93.4 88.0 369.0 260 283 300' 100 71.0

A __ 913.6 88.2 3169.8 265 283 3001 100 71.0

1 50 91.4 86.1 362.0 258 282 300 100 71.0

2 50 91.4 86.2 362.0 259 283 300 100 ‘71.0

3 50 90.5 85.3 358.0 256 283 300 100 72.0

6 50 91.4 86.0 361.0 258 282 300 100' 71.0

‘ 7 50 89. 9 84 .6 355.0 256 277 300 100 70. 0

9 50 91 .2 85 . 7 360. 0 257 282 300' 100 71 .0

62631 _____________________ __ 10 50 _ 87.4‘ 86.1 362.0 258 295 300' 100 71.0
Average (9)---- _______________________ __ 91.1 86.2 362.1 259 283 3100' 10-0 71.0

Cottonseed oil

——-_ ____________________ __ 2 l5 225.0 200.9 843.8 090 307 343 [l4 81.8
*1 ___________________ __ 3 20 225.0 213.0 895.0 520 231 244 81 58.0
i ____________________ _- 6 20 225.0 208.3 875.0 364 162 175 58 41.6
———-_-___-___-_____ . -. l0 ‘ l0 102.9 219.4 921.0 450 2 205 68 49.0

LI S-CIEIELJ NIVLHHO JO LOHEINEI HALLOIICIOHJ

Table 9. Productive energy in terms of feed, effective organic constituents, eifective digestible nutrients

and
metabolizable gnergyw-Continued
Productive energy
Effective Efiec- Metabo- w
Per organic tive lizable Total Eflec- Eflec- Rankwith In per-
Name and laboratory Exp. cent con- digestible 6119183] feed tive tive effective centflglwf
number of feed N0, of stituents nutrients Cal. Oal . organic digestible digestible metab0liz-
ration per can; p91- Qent per 100 gm. per 100 gm. consti- nutrients nutrients able
tuents .i oi corn energy
per 100 gm. per 100 gm. meal as 100
Cottonseed oil (Contfd)
- ................... _- 10 2o 118,0 221,8, 957-0 541 240 237 79 57.0
———- ------------------- -_ 10 30 129.6 2.18.5 913-0 4W 219 225 75 64.0
Average (6)-__- ______________________ __ 170.9 214.7 901-6 510 22!? 238 79 56.9
Kafiir
43057- ................... __ A __ 90,2 e313 350.0 26s 2.9a s19 1oe_ 76.0
Oat meal
43609- ___________________ __ O __ 94,1 83,9 373-0 236 251 265 , 88 66.0
Starch
52141_ ___________________ __ 2 5c sea 84.6 355-3 251 280 29'? 99 70.6
60165- ___________________ __ e 50 89,2 94.9 357-0 218 244 257 86 61.1
6067a ___________________ __ 7 50 86,9 34,0 353-0 239 275 285 95 68.0
Average (e)____ ______________________ _- $8.6 84.5 355.1 23a 20a 280 we 66.6
Wheat flour
44490_ ___________________ _ _ 13 __ 83.1 s6. 7 364.0 252 286 291 9v 69
51962 ___________________ __ 1 88.3 82.2 345-0 219 248 2166 89 63
Average (2) __________________________ __ 88.2 84.5 354.5 236 267 279 93 66
Wheat flour, Graham
44496- -------------------- -- B -- 86-4 80-6 339-0 249 288 309 103 73

8T

NOLLViLS LNQINIHHGIXH TVHfliT/IIIOIHSV SVXELL 'Z99 'OL\T. NLLHTIQH

Table 9. Productive energy in terms of feed, Oflective organic constituents, eflective digestible nutrients and
, a metabolizabie energy-Continued
Productive energy
Efifective Eflec- Metabo-
Per organic tive- lizable Total Efiec- Eifec- Rank with In per-
Name and laboratory Exp. cent con- digestible energy feed tive tive efiective centageiof
number of feed No. of stituents nutrients Cal. Cal . organic digestible digestible metaboliz-
ration per cent per cent per 100 gm. per 1001 gm. consti- nutrients nutrients able
~ ~ tuents . of corn energy
per 10-0 gm. per 100 gm. meal as 100
Wheat bran mixture
(human food)
43635 (Kellogsrs) -------- -_ 0 -_ 81.0 55.7 234.0 144 17s 250 se e2
43066 (Kelloggb) -------- _- A -_ 80.1 49.1 206.0 185 231 s77 120 90
44488 (Kelloggb) ________ __ B -_ 79.3 55.7 234.0 191 241 x4e 114 s2
Average (3)____ ______________________ __ 30,3 53,5 224,7 173 21a 326 109i 78
Wheat bran (commercial)
51901- ___________________ __ 1 50 79.2 45.7 192.0 119 150 2B0 87 62
59669 ____________________ __ s 50 73.2 47.1 198.0 125 160 265 88 63
62941- ___________________ __ 9 50 76,5 47,2 198.0 113 148 W 80 57
Average (3)____ 79,0 46,7 196.0 119 153 255 851 61
Wheat gray shorts
43054; ___________________ __ A __ 85.7 629.9 378.0 250 292 278 93 66
51962 ____________________ -_ 11 50 84.6 62.3 262.0 179 212 287' 96 68
62939 ____________________ __ 9 50 80.7 61 .7 260.0 174' 2161 282 94 67
Average (3)---- ______________________ __ 83.7 64,6 300.0 201 240 282 94 67
Yeast

4 ____________________ __ 7 30 81. 2 67.4 283.0 146 180 217‘ 72i 52'

(512940 ____________________ __ 9 30 88.9 65.0 273.0 101 114 157 5'2 37
Average (2)---- 1 _____________________ __ 85.1 66.2 278-0 124 147 137 62 45

61 SGEIEIJ NIVLHELO J0 LBHHNEI EIAIKLOIIGOHAT

20 BULLETIN NO. 632, TEXAS‘ AGRICULTURAL EXPERIMENT STATION

were used in the final calculations as follows: Wesson oil 5.10, starch
2.34, casein 2.08 and corn meal 2.64 calories. The effective digestible
nutrients of the feeds compared with corn meal were calculated from
the digestion experiments made on the rations by methods similar to
those used for calculating the productive energy, as described above.
That is to say, the quantities of total digestible nutrients of the test
ration were subtracted from those of the standard corn meal ration
and the calculations completed in a way similar to that for productive
energy.
Productive Energy of the Feeds

The productive energy of certain feeds, as found in each test, of their
effective organic constituents, and of their effective digestible nutrients,
when compared with that of corn meal as 100, are given in Table 9.
The work here presented reports 30 comparisons on 11 kinds of feed.

The differences in the Values of the same feed found in different
experiments are greater in some cases than are desirable.‘ The errors
of lthe work on the digestion experiments as well as those which occur
in determining the productive energy have some effect on the results
for the productive energy. The differences may also be due in some
experiments to the amount of energy used for maintenance from the

standard corn meal ration being different from that used for mainte"

nance from Ithe test ration compared with it. It is considered, however,
that the average values are approximately correct. _

The average productive energies of the different feeds range from 124
calories per 100 grams for yeast to 510 for cottonseed oil, compared
with corn meal, which usually had a value of about 259 calories per
100 grams. ‘

Variations are to be seen. with different experiments on the same kind
of feed. If Ithe individual tests are also studied, differences are found
in the ability of individual rats to utilize the ration in the same experi-
ment as shoWn in Tables 6 and 8. Since these differences occur for both
the standard ration and the test rations, the average results from dif-
frent tests of the same feed may be expected to differ. Thus the pro-
ductive energy of different feeds should be calculated from the results of
several experiments, each of which is the average of several individual
tests. Tests made on a few individuals may not be correct. When equal
quantities of digestible nutrients are compared, the productive energy
of the feeds used (Table 9) does not deviate widely from that of corn
meal. Rats, and chickens (10), utilize the nutrients which they digest
to an equal extent. Differences in the foods are due more to differences
in digestibility than to differences in the productive energy of the nutrients
digested.

Net Energy Determined Elsewhere

The net energy for rats of beef muscle protein, dextrin, lard and a
mixture of the three was reported by Forbes‘ et al. (1), in which the
food tested was added to a basal diet. The work was done by respiration

 

PRODUCTIVE ENERGY OF‘ CERTAIN FEEDS‘ 21

Table 10. Net energy in Calories per gm. as calculated by Forbes. et a1-
Compared. with Texas work

  

Beef
muscle Dextrin Lard Mixture
protein Cal. Cal. C‘
Cal.
Forbes et al.:
Exp. 1——rats about 100 gm ___________________ -- 1.19 1.72 6.59 4.41
Exp. 1—-rats about 240 gm._ 1.38 1.99 6.06 4.83
Exp. 2—rats about 100 gm._ 1.24 2.15 6.28 4.89
Exp. 2-rats about 2004 gm ___________________ -_ 1.85 2.25 6.12 5.07
Average (4) _________________________________ __ 1.42 2.03 6.26 4.810
Average, 1.72 excluded _____________________ __ 2.13
Calculated net energy of mixture ______________________________________________ -- 4-56
Productive energy Texas experiments:
Casein, rats ___________________________________ _- 2.10 ____ ___- ___-
Casein, chickens_ _____________________________ -- 2.24 ____ _-__ -_--
Starch, rats _______________________________ _,___-_ ____ 2.36 _-__ ____
Starch, chickens_ _____________________________ __ ____ 2.17 ____ ____
Cottonseed oil, rats __________________________ __ ____ ___- 5.10 __-_
Cottonseed oil, chickens- ____________________ __ ____ _-__ 4.67 _-_-

methods. The values for net energy are summarized in Table 10. The
mixture consisted of 62.5% of lard and 18.75% each of dextrin and beef
muscle. The net energy value of the mixture calculated from the average
net energy value of its constituents as shown in Table 10, would be
4.56 calories per gram. The average value found of 4.80 was not far
from this. The results do notjustify the claim that the net energy of
a. mixture must be different from “the net energy of the ingredients.

Texas experiments were not made on the same kinds of feeds as used
by Forbes et al. but the results for foods of similar classes with rats
and with chickens are given in Table 10. The net energy value of beef
protein of 1.42 calories per gram was much lower than the 2.10 calories
for casein with rats and 2.24 calories with chickens. The value of
2.03 calories per gram for dextrin was lower than the 2.36 calories for
starch by rats and 2.17 calories for chickens. These values would be
closer if the low value of 1.72 calories per gram obtained in one of the
Forbes experiments is excluded, then the average for dextrin would
become 2.13 calories per gram. The average value of 6.20‘ calories per
gram with lard is appreciably higher (than 5.10 calories per gram for
cottonseed oil with rats and 4.67 calories for chickens obtained in the
Texas work.

Comparison of Rats and Chickens

Some comparisons of rats and chickens on the corn meal ration are
given in Table 11. The chickens on experiment gained more weight in
21 days than the rats gained in 28 to 35 days. The chickens also stored
up a much greater proportion of the energy of feed, 57.9 per cent, than
the rats, 32.4 per cent, so that the rats used a much greater proportion

22’ BULLETIN NO. 632, TEXAS AGRICULTURAL EXPERIMENT STATION

Table 11. Comparison of rats with chickens (Bulletin 600) on the
corn meal rations

Rats Chickens

Period of experiment _____ 28or35 days 2.1 days
Average weight: by periods, gm _ 1014 121
Energy used for gain, per omit 32.4 57.9
Average fat content 12.4 9.7
Standard deviation of fat content 1 8 1.6
Used for maintenance per day per 100 grams,

productive energy, Calories 15.5 13.2
Standard deviation for maintenance- ____ 1 1 0.9
Used for maintenance per day per 100 grams,

metabolizable energy, Calories 21.8 18.2
Standard deviation of productive energy .......................... -- _--_ 19.6

of rations——wheat bran _ .06 .08

Wheat gray shorts ration .13 .09

Patent flour ration .10 .09

Starch ration .11 .12

Cottonseed oil ration .23 .24

Casein ration .09 .12

Yeast ration .10 .12

of their rations for maintenance purposes. The average fat content of
the rats was greater, 12.4 per cenlt, that of the chickens 9.7 per cent,
and the fat content was slightly more variable in the rats, the standard
deviation being 1.8 compared with 1.6 for the chickens. The average
calories of productive energy used for maintenance by the rats per
100 grams was 15.5 calories compared with an average of 13.2 for
chickens in one series (5) and 14.2 in another (10), while the metabo-
lizable energy used for maintenance was 21.8 calories compared with 18.2
and 1.9.6 for the chickens. The average difierence in energy used for
maintenance was not Wide, but seems to be real and not due to varia-
tions. The productive energy values of the rations seem to vary a little
more with chickens than with rats.

On account of the greater percentage of the ration stored by chickens
and the greater gains in weight as well as the fact that a desired number
of chickens can be secured at one time more readily than is the case
with ra-‘ts, the chickens seem to be the preferable animal to use in this
kind of work. ~

Comparisons of the average productive energy values secured by use
of rats and of chickens are given in Table 12. The productive energy
of the total feed and of the effective organic constituents is as a rule
higher for rats than for chickens. The utilization of the digested material
is best compared on the basis of the productive energy of the digested

materials compared with those of corn meal taken as 100. The energy .

of the digested constituents from cottonseed oil, kafir, wheat flour, wheat
gray shorts and yeast is used practically the same by rats and chickens.
The differences are not large with starch and wheat bran. The greatest
differences are with casein, oat meal, wheat flour and wheat bran mixture
(human food). On account of the limited number of experiments with
these feeds, no great emphasis can be placed on these differences, with
thepossible exception of-casein. For casein the standard deviation of

PRODUCTIVE ENERGY OF CERTAIN FEEDS’ 23

Table 12. Comparative productive energy of feeds for; rats and chickens

Total Effective Effective Rankwith In
feed organic digestible effective per- Num-
Gal. consti- nutrients digestible centage ber
Name of feed per tuents Gal. nutrients of metab- 0'1
100 Gal. per per of corn olizable sam-
gm. 100 gm. 100 gm. meal as 100 energy ples
Beans, navy, cooked, rates--- 165 184 219 73 52 _-
Casein, rats ................... -_ 210 239 264i 88 63 E 4
Casein, chickens .............. -- 224 256 317 105 76 6
Corn meal (standard), rats--- 259 283 300 100 71 --
Corn meal (standard),
chickens 241 264 300 100 72 --
Cottonseed oil, rats __________ __ 510 22.7 238 79 57 0
Cottonseed oil. chickens ..... -- 467 208 2317 79' 57 6
Kaflr, rats- ................... -_ 256 295 s19 106 7e 1
Kaflr. chickens ................ -- 231 254 ace 102 7s 2
Oatmeal, rats _________________ __ 23a 25-1 265 gs as 1
Oatmeal, chickens ............ -- 235 24s 297 9e 71 6
Starch, rats ___________________ __ 236 25c 280 93 61 3
Starch, chickens _____________ __ 217 245 252 3v 6.2 7
Wheat flour, rats _____________ ,_ 236 257 279 93 6g 2
Wheat flour, chickens _______ __ 214 243 2&9 941 68 6
Wheat flour, Graham, rats--- 249 288 309 103 73 1
Wheat flour, chickens _______ -_ 176 203 276 9'2 66 2
Wheat bran mixture (Human
100d)» Pats ----------------- -- 173 216 3% 109 7e 3
Wheat bran mixture (Human
food), chickens _____________ __ 145 134. 270 9O 64 2
Wheat bran, commercial,
rats- ------------------------ -- 119 15s 255 e5 e1 3
Wheat bran, commercial,
chickens _____________________ __ 100 125 27g 91 65, 6
Wheat gray shorts,
rats- ________________________ __ 201 240 282 94 67 3
Wheat gray shorts,
chickens _____________________ __ 144 171 2,83 94 67 7
Yeast, rats ___________________ __ 124 147 137 e2 475 2
Yeast, chickens- _____________ __ 86 100 188 63 45 2

the 88 calories of the productive energy found for- the rats is 22, and for
the 76 calories found with chickens is 18. Statistical analysis show that
T required for significance is 2.3, while T found is 1.3, so that the
difierence is not significant. '

The digestible nutrients of foods are in general utilized for energy by
rats to the same extent as those of cornf meal, and as a rule do not
deviate Widely from that of corn meal. There are some differences, but
most of them are not far from ‘the value for corn meal. The digestible
nutrients of yeast have a value of 62 for rats and 63 for chickens, com-
pared with corn meal as 100. This 10w value is probably due to the poor
quality of the amino acids present.

24 BULLETIN NO. 632, TEXAS‘ AGRICULTURAL EXPERIMENT‘ STATION

The energy value 0f the effective digestible nutrienrts of cottonseed oil
is 79 compared with those of corn meal as 100 for both rats and chickens,
showing that oils are not utilized as well for storage of energy as protein
or starch, and that the relative value of fats to carbohydrates is 1.8 in-
stead of 2.25 generally used.

Retention of the Protein

Analyses of the rats, of the rations, and the digestion experiments,
furnished datav- as to the retention of the digestible protein by the rats.
These data are summarized in Table 13. The calculations were made
from the average data, not for each individual as in the other work here
presented, the method of calculation has been described (9). The diges-
tible protein retained by chickens averaged 42.5 per cent as reported
in Bulletin 571 (5), and 50 to 56 per cent of the corn meal ration con-
taining about 20 per cent protein in (9) Bulletin 600. With the rats
on the corn meal ration, Table 13, it ranged from 32 to 40 per cent.
The chickens, therefore, stored higher percentages of the protein than
did the rats. This is in accordance with the storage of lower percentages
of productive energy by the rats.

Acknowledgment

Credit is due Mr. S. M. Greenberg, Dr. R. Reiser, Mr. E. C. Carlyle,
Dr. F. J. McClure, Dr. J. F. Fudge, S. E. Asbury and other members of
the staff for care and feeding of rats, analyses and other work necessary
to the calculation of the data here presented.

Sununary

The productive value of the energy of 11 kinds of feeds in 30 com-
parisons with corn meal was studied by means of the gain of protein
and fat by growing rats. The feeds studied include beans, casein, cotton-
seed oil, kafir, oatmeal, starch, wheat flour, wheat bran, Wheat gray
shorts and yeast..

The growing rats used for maintenance an average of 15.5 calories of
productive energy or 21.5 calories of metabolizable energy per day
per 100 grams.

The average productive energy of the feeds tested ranged from 124 cal-
ories per 100 grams for yeast to 510 calories for cottonseed oil. Dif-
ferences in the energy values of different feeds are due chiefly to
difierences in digestibility and to much less extent to differences in utiliza-
tion of the digested nutrients.

Rats gained less weight in 28 to 35 days" than chickens in 21 days,
stored a smaller percentage of the energy of the food, used a larger
percentage of the food for maintenance and contained a higher per-
centage of fat. The rats used more calories for maintenance per 100
grams than the chickens and stored smaller percentages of the digestible
protein. In spite of these differences, the energy values of the digested

Table 13. Protein gained by rat and eaten 1n ration

 

Avenprotein In Rats In Ration Digestible
Laboratory Name of Ration in live wt. of Retained
Number V rats in begin- A_t begin- At end Gain Average Digestible by rats
- ning % mng gm. gm. gm. gm. gm. %
51960 Corn meal (50.0) Exp. 1 __________________ __ l I 7.15 29.80 22.65 74.06 67.52 33.55
51961 Wheat bran (50.0)- _______________________ -- 1 7.24 25.05 17.81 86.05 73.37 24.27
51962 Wheat gray shorts (50.0) _________________ __ 17.69 7.06 28.62 21.56 86.69 75,43 23.53
51963 Patent flour (50.0) ________________________ __ 7.13 27.35 20.22 67.52 61.95 32,64
52141 Corn meal (50.0) Exp. 2 __________________ __ 6.96 31.41 241.45 68.33 62.03 39.42
521% Starch (50.0) ______________________________ __ 6.96 28.13 21.17 54.8.9 501.05 ' 42.34
52124 Casein (25.0)- _____________________________ __ 17.95 6.98 28.06 21.08 106.52 98.01 21,51
_____ Cottonseed oil (15.0) ______________________ __ 6.91 31.93 25.02 54.20 48.87 51.201
59686 Corn meal (50.0) Exp. 3 __________________ __ 1 f 6.43 34.77 28.34 84.47 75.76 37.41
__--- Cottonseed oil (200)---- l j 6.40 32.83 26.43 63.2.2 56-65 .65
59669 Wheat bran (50.0)- _______________________ __ J 16.93 I 6-31 28-92 22.61 106.27 89.85 25.16
59109 Casein (30.0) ______________________________ -_ 6.59 30-29 23.70 147.91 137.19 17.28
6016s Corn meal (50.0) Exp. 6 .................. -- 1 I 6.34 31.47 25.13 73.39 70.72 35.53
_-__- Cottonseed oil (20.0) ...................... _- J 6.40 31.63 25.23 68.08 60.95 41.39
60165 Starch (50.0)- _____________________________ -_ 17.92 l 6.40 30.42 24.02 66.35 59.97 40.015»
60164 Casein (30.0) ______________________________ _- t 6.214 29.07 22.83 142.78 132.24 17 26
60676 Corn meal (50.0) Exp. 7 __________________ __ I 8.30 312.44 24.14 66.06 60.21 40.09
60673 Starch (50.0) ______________________________ __ 8.14 29.12 20.98 501.72 45.48 46.13
60072 Casein (W0) ______________________________ __ 18.13 1 8.32 31.35 23.03 120.54 111.38 20.681
60674 Brewers yeast (mo) ______________________ __ 8.39 29.73 21.34 99.56 87.39 24.42
62938 Olorn meal (50.0) Exp. 9 __________________ __ 71.23 31.70 24.47 84.36 76.51 .98
62939 Wheat gray shorts» (50.0) _______________ __ 7.23 29.29 %.06 103.16 90.02 24.51
62941 Wheat bran (50.0)- _______________________ __ 18.84 7.10 27.32 20.22 111.16 94.89 21.31
62940 Brewers‘ yeast (30.0)- _____________________ __ 7.14 27.95 20.81 107.60 92.85 22.41
63631 Oorn meal (50.0) Exp. 10 _________________ _- 7.57 29.66 22.09 68.10 62.42 35.39
_____ Cottonseed oil (10.0) ______________________ __ 7.50 30.44 22.914 64.75 58.94 38,92:
_____ Cottonseed oil (20.0) ______________________ _- 18.43 7.52 31.13 23.61 60.29 54.90 43.01
_____ Cottonseed oil (30.0) ______________________ __ 7.41 24.44 17.03 42.47 38.54 44.19

SCIEIHJ-NIVLHEIO JO LOHEINEI HALLOIIGOHJ

26 BULLETIN NO. 632, TEXAS AGRICULTURAL EXPERIMENT STATION

nutrients as measured by means of rats was nearly the same as when
measured by means of chickens.

The productive energy of oil as measured by both rats and chickens
was 79 compared with 100 for corn meal. Oil has a value of 1.8 times
that of carbohydrates instead of the 2.25 times it is usually supposed
to have.

REFERENCES

1. Forbes, E. B., Bratzler, J. W., Thacker, E. J. and Marcy, L. F., 1939.
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2. Fraps, G. S. 1928. Digestion and production coefficients of poultry feeds.
Tex. Agr. Exp. Sta. Bul. 372. 24 pages.

3. Fraps, G. S. 1931. Digestibility by chickens of the constituents of the
nitrogen-free extract of feeds Tex. Agr. Exp. Sta. Bul. 437.

4. Fraps, G. S. 1937. Practical applications of productive energy values to
DTObIBIIZIS Zconcerning feeds and feeding. Proc. Am. Soc. An. Production.
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5. Fraps, G. S. and Carlyle, E. C. 1939. The -utilization of the energy of feed
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6. Fraps, G. S. and Carlyle, E. C. 1939. Utilization of the energy of wheat
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7. Fraps, G. S. and Carlyle, E. C. 1939-. Energy values of corn bran, rice
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8. Fraps, G. S. and Carlyle, E. C. 1939. Relation of gain in weight to gain
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9. Fraps, G. S. and Carlyle, E. C. 1941. Productive energy of corn meal,
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10. Fraps, G. S. and Carlyle, E. C. 1943. Productive energy of some feeds
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11. Fraps, G. S., Carlyle, E. C., and Fudge, J. F. 1940. Metabolizable energy
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12. Kibler, H. H. and Brody, Samuel. 1942. Metabolism and growth rate. of
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