THE FEED REQUIREMENTS OF FARM ANIMALS 129 



Thus one calculates the requirements for a 1250 pound cow 

 giving 40 pounds of 3.5 per cent milk as follows : 



The ration is then formulated in the usual manner. 



Other Standards. — Inasmuch as a considerable number 

 of feeding standards have been proposed, and as a number 

 of investigations upon the requirements of farm animals for 

 different purposes have been reported recently, it may be of 

 value to discuss some of them. 



Requirements for Maintenance. — A maintenance ration 

 is one just sufficient to prevent any loss or gain of tissues 

 in the animal body when there is no production. Theoreti- 

 cally a maintenance ration supplies just enough digestible pro- 

 tein to furnish the necessary amino acids for the repair of 

 the protein tissues of the body, and just enough net energy 

 to carry on the vital processes. It supplies the quantity of 

 feed necessary to simply support the animal when doing no 

 work and when yielding no material product. Although in 

 practical feeding simple maintenance is usually (though not 

 always) avoided, nevertheless a knowledge of the mainte- 

 nance requirement is necessary in order to use many of the 



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