Nutrition of the Animal Body 



243 



latter is usually very expensive and would be advisable 

 only when the alfalfa was very cheap. Suppose we 

 decrease the alfalfa, increase the mixed hay, and leave 

 out the cottonseed meal, which may be done when we 

 feed rich nitrogenous hay, like alfalfa. Then we try: 



The result is quite close enough. Close observation 

 may suggest slight variations to suit the needs of differ- 

 ent animals. It should be understood that these "stand- 

 ards" are averages, and that particular animals may 

 require more or less than the amounts indicated. 



338. The Amount of Feed required depends on the 

 size and condition, and also on the individuality of 

 the animal. By many carefully conducted trials, inves- 

 tigators of feeding problems have made approximations 

 of the dry matter, protein, carbohydrates, etc., needed 

 per hundred or thousand pounds live weight of animal 

 per day. (See table of feeding standards in Appendix.) 



339. Roughage and Concentrated Foods. According 

 to the per cent of digestible nutrients in feed stuffs 

 they are classed as Roughage and Concentrates. Sub- 

 stances like hay, which contain a large per cent of undi- 

 gestible substance, are called Forage or Roughage, and 

 those like the grains, cottonseed meal, etc., in which 

 nearly all is digestible, are called Concentrates. Rough- 



