MAINTENANCE REQUIREMENTS OF MATTER 327 



and 0.25 pound of crude protein in experiments on dry cows, 

 while in experiments on steers almost as small a quantity, viz., 

 0.27 pound crude protein or 0.23 pound true protein, fell very 

 little short of maintaining the nitrogen balance. Aside from 

 these somewhat exceptional results, the lowest figures obtained 

 were 0.43 pound crude protein and 0.38 pound true protein. 

 If the few exceptionally low figures be omitted, the average and 

 range of the results of the other experiments are as follows : 



TABLE 60. AVERAGE AND RANGE or PROTEIN REQUIREMENT OF CATTLE 



It seems safe, therefore, to estimate 0.6 pound of crude pro- 

 tein or 0.5 pound true protein per 1000 pounds live weight as 

 representing in a general way the minimum protein require- 

 ment of cattle, with a range of perhaps o.i or 0.2 pound either 

 way under varying conditions. 



416. Protein requirement of sheep. While a considerable 

 number of experiments with sheep are on record in which live 

 weight maintenance was secured, and a smaller number in which 

 the nitrogen balance was maintained, few of them afford satis- 

 factory data as to the minimum protein requirement. 



A distinct difference between cattle and sheep, which affects the 

 protein requirement, lies in the greater demand for protein incident 

 to the growth of wool in the latter animals as compared with that of 

 hair in the former. Determinations by Armsby and Fries on the 

 same two steers in two consecutive winters showed an average pro- 

 duction of epidermal tissue, including the growth of hair and the loss 

 in brushings, equivalent to 0.0025 lb. protein per day and 1000 

 pounds live weight, an amount too small to materially affect the main- 

 tenance requirement. In the case of sheep, determinations by several 

 investigators have shown the daily growth of wool per 1000 pounds 

 live weight to contain from o.io to 0.15 lb. of protein, the average 

 being 0.135 lb. Although, as these figures show, the protein re- 



