976 
Journal of Agricultural Research 
Vol. XXIV. No. II 
cent by the com. McCollum (lo) has shown that a supplementary re¬ 
lationship exists between corn and soy-bean proteins in the ratio of 6 per 
cent of the former to 3 per cent of the latter. 
When the protein level of the com-soy-bean mixture was reduced to 
7.2 per cent, so that the com furnished 2.6 per cent and soy bean 4.6 per 
cent of the protein of the diet, decidedly better growth resulted than 
when com at the same protein level in an otherwise adequate diet was 
used. Rat 926 of this lot showed even a better than normal rate of 
growth at the end of about 95 days (Chart 7). 
During an eleven-week period, the rats of this lot (excluding rat 1041^ 
which for some reason other than a deficiency in the diet made practically 
Chart 7.—Curves showing the supplementary value of soy-bean proteins when fed with corn proteins, at a 
low protein intake levd. 
no growth) made an average gain of 1.48 gm. per gram of protein con¬ 
sumed. 
Table I .—Gain of body weight per gram of ingested protein 
Protein in— 
Gain per 
Diet.i 
Com. 
Concen¬ 
trate. 
Total. 
gram 
(11 weeks). 
Ck>m. 
Per cent. 
7. 2 
3 - I 
Per cent. 
Per cent. 
7.2 
7. 2 
Gm. 
0.73 
.94 
Com-}-tomato-seed press cake. 
4. I 
Com-}-peanut meal. 
2. 5 
4. 7 
7.2 
I. 23 
CornH-soy-bean meal. 
2. 6 
4. 6 
7. 2 
I. 48 
1 These diets were made adequate with respect to the nutritionally essential factors other than proteins. 
(See charts.) 
Although the ratio of the percentage of concentrate protein to corn 
protein is not exactly the same in these diets (Table i), it can safely be 
concluded that the growth-promoting value of the proteins of these con¬ 
centrates, as supplements to the proteins of com, is in the following order: 
Soy bean, peanut, and tomato seed. In the experiments with the coco- 
