2 BULLETIN 637, U. S. DEPARTMENT OF AGRICULTURE. 
Uy 
based only on chemical composition is to be taken merely as a guide, 
to be followed in the light of all the knowledge obtainable about 
animal nutrition. 
NEW METHOD OF BALANCING RATIONS. 
The method of balancing rations commonly used might well be 
called the ‘“‘Cut and Try Method.” It is faulty for the reason that 
it usually necessitates several trials to secure the desired result. By 
using the method described in these pages, balancing a ration is a 
caus matter of multiplication and division.t. ~ 
Table I gives the excess protein per pound for different protein 
feeds when used in rations of various nutritive ratios. ‘To illustrate: 
A hundred pounds of dried brewer’s grains contains 21.5 pounds 
digestible protein and 44.2 pounds digestible carbohydrates. A 
ration with a nutritive ratio of 1:4, requires only 11.05 pounds pro- 
tein to balance 44.2 pounds of carbohydrates. Hence, in such a 
ration, 100 pounds of this feed contains 21.5—11.05, or 10.45 pounds 
of excess protein. The excess protein in a single pound is thus 
0.1045 pound. (See Table I, column headed “Ratio 1 to 4,” oppo- 
site brewer’s grains, dried.) In rations having wider ratios the 
excess protein is proportionally greater. 
Some of the figures in Table I are printed in italics. These repre- 
sent deficiency instead of excess in protein. Thus, in a ration of 
ratio 1:4, a pound of rye is deficient in protein by 0.0798 pound, 
while in a ration of ratio 1:10, it has an excess of protein amounting 
to 0.0279 pound. 
In like manner Table If shows the protein deficiency per pound 
for various carbohydrate feeds as compared with rations of specified 
nutritive ratios. The italic figures in this table represent excess 
protein. Thus, in a ration of ratio 1:4, a pound of buckwheat is 
deficient in protein by 0.0572 pound, while in a ration with ratio 1:10 
it has an excess of 0.0257 pound of protein. 
1 The tables used in this bulletin are based upon Table III, Digestible nutrients and fertilizing constit- 
uents, in Henry’s “Feeds and Feeding.’’ It was necessary to include the digestible fat, with its equivalent 
fuel value (21 xcarbohydrate) with the carbohydrate in order to prepare the tables. In proposing a mathe- 
matical method for balancing rations different from the one commonly employed, the same assumptions 
are made as in the case of the usual method, viz, that fats have two and one-fourth times the feeding 
value of the carbohydrates and that a pound of carbohydrates or protein has a uniform value whatever its 
source. The latter assumption is, of course, not strictly true. Proteins differ somewhat in their nutri- 
tive value, and sugars have nutritive and physiological effects somewhat different from those of starches. 
Nevertheless, the assumption of the equality of value of these nutritive elements in various feed stufis 
introduces a no greater source of error in the method proposed in this bulletin than in the usual method 
of balancing rations. 
The method of balancing rations described in this bulletin is based on the principle (alligation) proposed 
by Prof. J. T. Willard in Kansas Experiment Station Bulletin 115, but the method of applying this 
principle is different, and is believed to be simpler and more convenient, especially when several feeding 
stufis are to be used in the ration. 
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