308 THE FEEDING OF ANIMALS 



hydrates which, because the income and outgo are bal- 

 anced, are used solely as fuel. Only a very small amount 

 of protein is necessarily destroyed by a resting animal, 

 although a minimum supply is absolutely essential if the 

 nitrogenous tissues of the body are to be kept from wast- 

 ing. If an animal is not eating protein, the cleavage of 

 body protein will go on and urea will continue to appear in 

 the urine and in time protein starvation will cause death. 



407. Uses of production ration. Any ration, fed for 

 production, may be looked upon as made up of two parts, 

 that which is needed to maintain the animal and that 

 which may be applied to growth or the formation of 

 milk solids. It is possible, of course, for the produc- 

 tion of milk or wool to occur when the cow or sheep is 

 fed what is really only a maintenance ration, but the 

 materials for production under these circumstances are 

 furnished at the expense of the body substance. With 

 what is regarded as liberal feeding, from one-third to 

 one-half of a production ration is needed for mainte- 

 nance purposes. It seems fitting, then, to speak of a main- 

 tenance ration as a fundamental quantity, a knowledge 

 of which is important to both science and practice. It is 

 clear that no rational understanding of the uses of food 

 can be had, unless we know what amount is required 

 simply for maintenance, and the feeder is certainly helped 

 to a more intelligent compounding of rations if he has some 

 means of judging how large an excess he is supplying for 

 production purposes. Occasionally, too, it is desired to 

 provide horses and other animals when not at work with 

 just enough food to keep them in a uniform condition 

 without gain or loss. 



408. Maintenance ration easily provided. No ration 

 is more easily provided from the ordinary farm supply 



