62 



PniNCIPLES OF FEEDING FARM ANIMALS 



consumed, and the percentage of it which is digestible, one 

 obtains the amount of each digestible nutrient in the corn 

 by multiplying the total amount of each nutrient of the corn 

 by its coefficient of digestibihty and dividing the result by 

 100. Obviousl}^, subtracting the amount of digestible nu- 

 trients of the corn from the digestible nutrients of the total 

 ration leaves the amount of nutrients digested from the 

 tankage. Then dividing the amount of each nutrient di- 

 gested from the tankage by the amount of the correspond- 

 ing nutrient consumed from the tankage, and multiplying 

 the result by 100 gives the coefficients of digestibility of the 

 nutrients of the tankage. 



Returning to the example cited, the coefficients of diges- 

 tibihty of tankage are calculated as follows : 



Digested from total ra- 

 tion 



Digested from corn . . 



Digested from tankage . 



Coefficient of digesti- 

 bility of tankage (per- 

 cent) 



Fat 



Lb. 



1.75 

 0.65 

 1.10 



114.59 



This indirect method of calculating the coefficients of 

 digestibihty is open to criticism because all of the difference 

 between the values for the single feed and the corresponding 

 values for the combined feeds is credited to the single feed, 

 whereas it is probable that in the combined feeds each feed 

 exerts an influence upon the digestibihty of the other. Also 



