FEEDS AND FEEDING 383 



It is evident that feeds of animals cannot be deter- 

 mined by rule. For the best results, the judgment of 

 the feeder guided by rules should be used in feeding 

 each animal. 



Note. The expression in percentage showing what part of a food 

 element is digestible is called the coefficient of digestibility. If we 

 know the weight of protein, for instance, in a given food, we may find 

 the amount available for any class of animals by multiplying this weight 

 by the coefficient of digestibility. 



Feeding for Maintenance. Scientists have deter- 

 mined quite accurately just the amount of food re- 

 quired to keep an animal in normal condition without 

 increasing or decreasing in weight and without giving 

 any product or labor. This is called a ration for main- 

 tenance. For instance, it has been determined that 

 the average dairy cow, for each 100 pounds of her 

 weight, requires for her maintenance under normal 

 conditions each day : 



Protein .07 Ib. 



Carbohydrates .7 Ib. 



Ether extract, or fat .01 Ib. 



Other classes of animals require other proportions 

 for maintenance. The maintenance ration is required 

 for keeping up the body so that it may be in condition 

 to give work or product, much as coal must be consumed 

 under the boiler to warm the water before steam for 

 work is formed. 



Ration for Product. After the animal has its 

 maintenance ration, the additional food that is given 

 may result in some valuable product. That may be 

 increased growth, fat, milk, wool, eggs, or performance 

 of work. 



