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 Faitening Steers, in Per Cent 
a. Ash Protein Fat 
Oxen fattened very young......... 63 to 68) 2.25 10 50 to 55 
Mature animals, final period....... 70 to 75) 1.5 7 to 8 | 60 to 65 
Well-fed steers, growth from 17 to 27 
months of age............... | 87.6 6.0 14.1 37.5 
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 
_Tequire 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 14% years old, 2.0 pounds. 
2 years old, 1.75 pounds. 
24, 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 the 
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 
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