70 



GROWTH 



cereals are low in protein, and that is true. The proteins them- 

 selves, however, are also of poor quality. The example we have 

 chosen is adapted from data published 1 a few years ago on the 

 nutritional requirements of swine. 



Table I 



THE BIOLOGICAL VALUE OF THE PROTEINS OF CORN AS 

 COMPARED WITH CASEIN 



Lot no 31 



Nutritive ratio 1 :8.8 



Corn 97.5 



Casein 



Starch 



Salt mixture . . . . 2.5 



Ration 



_. . \ Corn 

 Protein < c . 



I Supplement 



Ether extract 

 N-Free extract . 

 Ash 



Avg. initial wt. 7-3-' 15 

 Avg. final wt. i2-30-'i5 . 



Gain 



Total dry matter consumed 



Per cent 

 10.88 



4.58 

 80.30 



4.27 



Lbs. 

 25.3 

 37.6 

 12.3 

 114. 6 



34 



1:8.8 

 25.00 



3.00 

 21.40 



1.24 



Per cent 

 5.64 

 4.87 

 3.02 

 82.80 

 3-73 



Lbs. 



24.0 

 164.7 

 140.7 

 433-6 



36 

 1:6 

 50.00 

 2.82 



1.32 



Per cent 

 10.29 



4.21 



4-97 

 76.15 



4-33 



Lbs. 



20.3 



200.0 



179.7 

 5I3-2 



35 

 1:3 



50.00 

 11.68 



i-54 



Per cent 

 8.77 



14.91 

 5.92 



65.80 

 4.51 



Lbs. 



19.7 

 200.7 

 181. o 

 530.2 



You will note that the ration of corn alone barely sufficed for 

 maintenance. The ration of the second group was approximately 

 the same as that of the first, if we suppose that about one-half 

 of the corn protein had been replaced by casein. The gains made 

 by this group were not rapid, but the total weight gained was 

 about twenty times more than that of the first group. This chart 

 also brings out another point — the supplementing value of un- 

 balanced proteins. We may say from previous experience that if 

 the only protein in this diet had been 4.78 per cent casein, there 

 would have been no gain. It is obvious that 5.64 per cent of 

 corn protein is ineffective, but the combination of the two is far 



