CHAPTER IV 

 THE DIGESTIBILITY OF FEEDINGSTUFFS 



From a nutritive standpoint, only those portions of the 

 nutrients whicli are digested and absorbed are of value to 

 the animal body. In a sense, food is not within th^ body 

 until it enters the l)lood. The undigested portion of the 

 ration, although it may })e of value in distending the digestive 

 tract and for other purposes, has no value as a means of 

 support to the animal. Hence a knowledge of the amounts 

 of the nutrients digested, and of the factors affecting the 

 digestibility of the nutrients of the various feedingstuffs, is 

 of considerable practical importance. 



Coefficients of Digestibility. — The process of digestion 

 in the farm animals usually is quite incomplete, the un- 

 digested portions of the ration being excreted in the feces. 

 Thus the amount of a nutrient digested is equal to the 

 amount of that nutrient consumed, less the amount of it 

 excreted in the feces. The percentage of the nutrient that 

 is digested is known as the " coefficient of digestibiUty." 

 The coefficient of digestibility is obtained by di\dcUng the 

 amount of the nutrient digested by the total amount of the 

 nutrient consumed, and multipl3dng the result by 100. 



Determination of Coefficients of Digestibility. — The 

 coefficients of digestibihty of the different nutrients of many 

 feeds have been determined by what are known as digestion 



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