THE FEED REQUIREMENTS OF FARM ANIMALS 125 



The Armsby standards express the requirements of farm 

 animals in pounds of digestible true protein (not crude pro- 

 tein) and in therms of net energy. Instead of giving separate 

 standards for all the different classes of farm animals, Armsby 

 gives standards for maintenance and for growth. Inasmuch 

 as any excess of feed above maintenance may be used for 

 fattening or milk production, he gives the amount of nu- 

 trients above the maintenance requirements necessary to 

 produce a pound of gain or a pound of milk. Thus, the 

 standards for fattening and for milk production vary with 

 the amount of gain or with the amount of milk produced. To 

 determine the standard for a fattening animal, one adds 3.5 

 therms for each pound of daily gain to the energy require- 

 ment for maintenance, as all the net energy above the 

 maintenance requirement may be used for the production 

 of flesh and fat. The protein requirement of an immature 

 fattening animal is, according to Armsby, the same as that 

 of a growing animal of the same weight, and the protein 

 requirement of a mature fattening animal is the same as 

 the protein requirement for maintenance. Armsby recom- 

 mends that a 1000-pound ruminant should receive 20 to 

 30 pounds, or an average of 25 pounds, of dry substance per 

 day. A horse should have somewhat less. The amounts 

 of digestible true protein and of net energy in the common 

 feedingstuffs as presented by Armsby are given in Table 31 

 of the Appendix. For example, if one desires to calculate 

 a ration for a 1000-pound steer gaining two pounds per day, 

 the first step is to determine the requirements. From Table 

 34 of the Appendix, it is seen that the requirements of a 

 1000-pound steer gaining 2 pounds per day are 1.8 pounds of 

 digestible protein and 13.0 therms of net energy. As the 



