6 N. H. EXPERIMENT STATION. [Bulletin 195 



water and mineral constituents. In addition there are other 

 things, known as ^'vitamines/' "growth promoting substances," 

 or "food accessories," the chemical nature of which is not well 

 understood, which are necessary. The latter substances, how- 

 ever, are usually present in sufficient quantities in our regu- 

 lar feeding stuffs and we need consider them no further. Our 

 feedstuffs usually contain mineral matter sufficient for the 

 needs of an animal with a few exceptions, such as calcium car-' 

 boijate, 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 since they are expensive and their content in feeds 

 largely determines its feeding value, we should consider their 

 use in the animal. 



 



The Functions of Foods in the Animal. 



Carbohydrates, protein and fat are sometimes called food 

 nutrients. These nutrients have two definite uses in the ani- 

 mal body. 



First, they furnish building materials to produce new tissues 

 in the growing animal, to repair the waste in tissues of the ani- 

 mal, and to make products such as milk, eggs, wool, etc. 



Second, they furnish (by being burned in the body) energy 

 to maintain body heat and to do work. All animals require 

 energy for their life processes. They require energy to move 

 about, to digest their food and to maintain their body tem- 

 perature. 



All three of the food nutrients can be used to furnish energy, 

 but the energy value per pound and the cost per pound is not 

 the same. Not all can, be used to build up all parts of body 

 tissues. Protein is definitely required for certain building 

 uses. For these reasons a knowledge of the uses of each nu- 

 trient will aid the practical feeder. 



The Function of Protein. 



The proteins form an essential part of every living cell. All 

 animals must secure their protein from the protein of foods. 



