96 



MAINTENANCE RATIONS OF FARM ANIMALS. 



On the average of the two animals, 0.41 pound digestible crude protein per 

 1,000 pounds live weight was apparently sufficient to prevent a loss of nitrogen 

 from the body. The crude protein in this case was practically all true protein, 

 only minimum amounts of nonprotein being present in the ration. Since, how- 

 ever, the growth of wool must have gone on, with a corresponding storage of 

 nitrogen, this apparent maintenance ration would really result in a loss of 

 protein by the active tissues of the body. 



If we add to Katayama's average 0.14 pound per 1,000 pounds 

 live weight for the growth of wool, we get 0.55 pound as represent- 

 ing the minimum protein requirement for the maintenance of mature 

 sheep, including the growth of wool. It is interesting to note that, 

 according to these figures, the actual maintenance requirement for 

 the body tissues is quite as low relatively as for cattle. 



It is true that some earlier experiments seem to indicate a greater 

 demand for protein than the foregoing figures show. Thus, in 

 the experiments cited on page 80 to illustrate the influence of the 

 protein supply upon its katabolism, a ration containing about 2.5 

 pounds digestible protein per 1,000 pounds live weight seemed to be 

 about sufficient for maintenance, including the wool production, 

 while a ration containing 2.27 pounds showed a loss of protein. Simi- 

 larly, in earlier experiments b}^ Henneberg, Fleischer, and Miiller, 1 

 a ration containing 1.25 pounds digestible crude protein following 

 one supplying 6.51 pounds resulted in a loss of protein by the animal. 

 Notwithstanding these isolated results, however, it seems justifiable 

 to accept the lower figure obtained by Katayama as representing ap- 

 proximately the minimum protein requirement of mature sheep. 



SWINE. 



The only data available as to the minimum protein requirement of 

 swine are derived from the two experiments upon fasting animals by 

 Meissl, Strohmer, and Lorenz (referred to on p. 51). The animals 

 were Yorkshire swine, one 14 months old and weighing 140 kilograms, 

 and the second, whose age is not given, weighing 120 kilograms. In 

 the fasting state the nitrogen excretion of these animals was as 

 follows : 





Live 

 weight. 



Nitrogen 

 excretion. 



Animal I: 

 Animal II: 



Average of third, fourth, and fifth days' fasting 



Kilos. 

 140 



120 



Grams. 

 9.80 



a. 7, 



The nitrogen excretion was equivalent, respectively, to 0.44 and 

 0.35 pound of protein per 1,000 pounds live weight, or about the 

 amounts which appear to be required for cattle and sheep. No 



1 Jahresbericht der Agricnlturchemie, vols. 16-17, II, p. 145. 



