FEEDING BEEF CATTLE 



257 



figures for the composition of the increase in weight of young and 

 mature fattening steers, the results shown in the first two lines 

 being obtained in English experiments and those in the third line 

 in American experiments: 



Composition of Increase in Fattening Steers, in Per Cent 



Even in animals that were fattened while very young, 37.5 to 

 50 per cent of the increase in body weight consisted of fat, 32 to 42 

 per cent was water, and 10 to 14 per cent consisted of protein. 

 With mature animals, on the other hand, 60 to 65 per cent of the 

 increase was fat, 25 to 30 per cent was water, and only 7 to 8 per 

 cent protein. This suggests that a large supply of protein to fatten- 

 ing animals is not all-important, as was formerly considered the 

 case. Practical feeding experience has shown that fattening animals 

 require only a small amount of protein for making good gains so 

 long as they receive plenty of digestible nutrients in their feed. 



Protein Requirements. The approximate protein require- 

 ments of cattle have been formulated by Armsby as follows, from 

 the results of a considerable number of experiments ; given in pounds 

 of digestible protein per thousand pounds live weight. 



1 to 3 months old, 4.8 to 3.5 pounds. 



1 to 1% years old, 2.0 pounds. 



2 years old, 1.75 pounds. 

 2% years old, 1.5 pounds. 



In mature fattening animals the protein requirements are very 

 small, as the formation of muscular tissue in these animals has 

 practically ceased and protein is mainly required for repair of the 

 body tissues. 



Since the protein requirements for fattening animals are much 

 lower than previously held necessary, the nutritive ratio of th? 

 rations fed may be much wider than that given by Wolff-Lehmann. 

 Careful experiments have shown that the nutritive ratio of fatten- 

 ing rations may range from 1 : 4 to 1 : 10 without affecting the gain 

 in body weight per unit of digestible matter eaten, provided the 

 feed supplied above maintenance be furnished by easily digestible 

 17 



