every 100 parts of corn meal the animal can use .84. These are 

 called digestihle nutrients.'^ 



You hear mucli about tlie " nutritive ration " in stock feeding, 

 and, perhaps, have been puzzled to lind out just what it means. I 

 liave told you that most feeding-stuffs contain both muscle-making 

 and fat-making food, but in different proportions. The '^nutritive 

 ratio " of the cheniist is simply the py^oportion or ratio between the 

 "protein and the carbohydrates. Take your corn meal, for instance. 

 It has 7 parts of muscle-making food and 76 parts of fat-making 

 food. Tliis would be the same as 1 part of muscle-making food to 

 about 9 of fat-making food. In the last column of the table, there- 

 fore, you will find 1 : 9.7, which is simply the comparative amounts 

 of the two kinds of foods. The two dots between the 1 and the 9 

 show tiiat one food is being compared with the other. It is very 

 important that you should know what the nutritive ratio is, for you 

 will need to use it when selecting materials for making a balanced 

 ration. 



One I'eason why John's cows gave more milk than David's was 

 because he fed them with wheat bran instead of corn meal. Let us 

 see how much protein and how much carbohydrates the chemist finds 

 in one pound of wheat bran. I have put his figures under those for 

 corn meal so you can compare the two easily. Do you not see that 

 the bran has 12 parts of muscle-making food, or nearly twice as 

 much as the meal ? Also, that it has over a third less of fat- making 

 food ? The proportion, or nutritive ratio, for wheat bran is, there- 

 fore, 1 : 3.7, since it contains 1 part of muscle-making food for every 

 3^^ parts of fat-making food. 



Here, then, is my argument : The wheat bran which John fed his 

 cows was nearly two times richer in muscle-making food than the 

 corn meal which David fed. Most muscle-making food is also 



* As a matter of fact, the column headed " Carbohydrates" is made up of both 

 carbohydrates and fats in food, the fat having been multiplied by 2^. This is 

 done solely as a matter of convenience in computation. The function of carbo- 

 hydrates and fats is identical, but fats will evolve 2i times as much heat as carbo- 

 hydrates; therefore, the percentage of fats has been raaltiplied by 3^ and added 

 to the carbohydrates. 



553 



