6 N. H. EXPERIMENT STATION. [Bulletin 200 



are necessary. The latter substances, however, are usually present in 

 sufficient quantites in our regular feeding-stuffs and we need con- 

 sider them no further. Our feeding stuffs usually contain mineral 

 matter sufficient for the needs of an animal with a few exceptions, 

 such as calcium carbonate, which we furnish, as oyster shells for 

 hens, so we need not consider the mineral matter further. 



The protein, fat and carbohydrates must be furnished in the 

 feed and it is their content which largely determines the value of 

 the feed. 



DIGESTIBILITY IMPORTANT IN DETERMINING 

 THE VALUE OF FEED. 



Not all of the protein, carbohydrates and fat in the different 

 feedstuffs are digested. In comparing the value of different 

 feedstuff s, especially when they are of different types, we must take 

 into consideration the digestibility of these food nutrients. The 

 coefficient of digestibility is a term v/hich expresses the percentage 

 amount of the food nutrients which are digested and absorbed by 

 the animal. These coefficients are determined by careful feeding 

 experiments which are conducted by the various experiment sta- 

 tions. Table number 3 gives a summary of the average results 

 for some of our common feedstuffs. 



