RATIONAL FEEDING OF ANIMALS 349 



feeding trials, 15 pounds digestible organic matter per 

 day for a looo-pound animal have been found sufficient. 

 A ration containing 15 pounds digestible dry matter, 

 about i. 80 pounds digestible protein, 1 3 pounds digestible 

 nitrogen-free extract compounds and o. 7 pound digestible 

 ether extract was found satisfactory. When too scant an 

 amount of protein is supplied in a ration, the meat is of 

 poorer quality than when more is available so as to pro- 

 duce a normal amount of circulatory proteids in the 

 system. In beef production, the aim should be to supply 

 sufficient available protein for maintenance purposes, and 

 a small amount for the other needs of the body, the fat 

 being produced from the less expensive nutrients as car- 

 bohydrates and ether extract. When the fat is produced 

 from an excess of protein in the food, the cost of produc- 

 tion is unnecessarily large. The protein supply in beef 

 production should vary with the stage of fattening. Ex- 

 periments at the Pennsylvania Station show that 0.42 pound 

 digestible protein, 6. 77 pounds digestible non-nitrogenous 

 compounds and 0.13 pound digestible ether extract are 

 required for maintenance purposes. At different stages 

 of growth, different amounts of food are required to pro- 

 duce a pound of gain. This fact is particularly notice- 

 able in experiments at the Kansas Station from which the 

 following data are taken : 



Grain required for 

 i pound gain . 



After 56 days 7. 30 



After 84 days 8.07 



After 122 days 8.40 



After 140 days 9.01 



After 1 68 days 9.27 



After 182 days 10.00 



