THE NUTRIENTS AND DIGESTION 329 



besides the chicken, however, and it is not possible to draw 

 general conclusions on the meager data available. 



Nutritive Ratio. — In order to quickly and conveniently 

 see the relation between the protein that is digestible for 

 poultry and the digestible carbohydrate and fat, what is 

 termed the " nutritive ratio" is made use of. The nutritive 

 ratio is an arithmetical proportion stating the amount of 

 digestible carbohydrate and fat (estimated as carbohydrate) 

 that fall to one part or one pound of digestible protein. 



It will be seen by referring to Table XL VI, that 100 

 pounds of corn contains 8.4 pounds of protein that can be 

 digested by chickens, 64.29 pounds of carbohydrate and 4.4 

 pounds of fat. As previously noted, fat has a feeding value 2.25 

 times that of carbohydrates. It is possible to estimate the 

 fat as carbohydrate by multiplying its weight by the factor 

 2.25. For the purpose of securing a simple proportion, the 

 equivalent of the fat in carbohydrates may be added to the 

 amount of carbohydrate found in the corn, giving the pro- 

 •portion of 8.4 pounds of protein to 74.19. pounds of 

 carbohydrate. In order to simplify this proportion and 

 make it comparable with all other similar proportions, both 

 amounts are divided by the amount of protein, giving the 

 porportion of one to eight and eight-tenths, and expressed 

 thus: 1: 8.8. This is called the nutritive ratio of corn for 

 chickens. Expressed arithmetically, the process is as follows : 



Digest, fat Digest, carbohydrate 



(4.4 X 2.25) + 64.29 ^ ^ ^ Second factor of 



8.4 ' nutritive ratio. 



Digestible protein 



The nutritive ratio of corn for ruminants is 1: 9.7. 



In calculating the nutritive ratio, care should be taken 

 to distinguish between the amounts of the nutrients consumed 

 and the amounts digested. Brown^ found 100 pounds of 

 hens fed on the exclusive diet of corn consumed 4.83 pounds 

 of organic matter daily, but they digested only 4.19 pounds. 

 The nutritive ratio for corn, as may be seen from Table 



' Bureau of Animal Industry, Bulletin No. 56. 



