Sept., 1920] INSPECTION of feeding stuffs. 7 



They cannot make it from tbe more simple inorganic com- 

 poimds, as plants do. Protein in main forms the muscular 

 tissues, hair, hoofs, horns, etc. Milk and eggs contain large 

 quantities of protein. The young growing animal or the one 

 producing milk or eggs requires more protein than the mature 

 animal or the one which is not producing materials. When a 

 surplus of protein above the needs of the animal is fed it does 

 not store protein but burns it to produce heat or converts a part 

 of it into fat. This is an expensive source of energy or fat, 

 however, inasmuch as carbohydrates which are less expensive 

 can furnish this need. 



The Functions of Fat. 



Fat is burned in the animal body to furnish energy as heat 

 or muscular work or is stored in the animal as body fat. Al- 

 though one pound of fat is equivalent to 2.25 pounds of carbo- 

 hydrates in energy value, the fat is more expensive and is next 

 to protein in cost. 



The Functions of Carbohydrates. 



Carbohydrates are burned in the body to furnish heat or 

 energy for work and also may be converted into fat and stored 

 as body fat. Carbohydrates are cheaper than protein and fat. 



Analysis Alone Not Sufficient to Determine Value of Feed. 



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

 feedstuffs are digested. In comparing the value of different 

 feedstuffs, 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 which 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 stations. jTable l!Tumber 3 gives a sum- 

 mary of the average results for some of our common feedstuffs. 



