292 NUTRITION OF FARM ANIMALS 



was available for maintenance as in the case of the hays exclu- 

 sive of alfalfa investigated by Armsby and Fries, 1 viz., 52.8 per 

 cent. For the mixed rations a percentage of 55 has been as- 

 sumed. In Evvard's experiments the net energy was computed 

 by that investigator. Eckles 2 has also reported five determi- 

 nations of the live weight maintenance of dry cows in which 

 the net energy values of the mixed rations consumed were 

 estimated from the writer's computed averages. 3 



The results of the computations are shown in Table 48, 

 Armsby and Fries' determinations of the net energy require- 

 ment being included for comparison. 



For the medium and thin animals, the estimated net energy 

 of Kellner's maintenance rations is distinctly less than the 

 average maintenance requirement found in Armsby and Fries' 

 experiments. The mean of the individual results of the two 

 experimenters, on 16 different animals, is 5934 Cals. The 

 average estimated net energy in the maintenance rations of the 

 live weight experiments is somewhat greater, viz., 6181 Cals., 

 although if the one apparently exceptional result obtained by 

 Evvard be omitted, the average is reduced to 6113 Cals. The 

 maintenance requirement of fat cattle is evidently distinctly 

 greater than that in the unfattened state but the data are too 

 few to permit the statement of a trustworthy average. 



It appears, then, that the maintenance ration of mature 

 cattle in thin to medium condition must supply, on the aver- 

 age, about 6000 Cals. of net energy per thousand pounds live 

 weight, although with considerable variations from this average 

 in individual cases. That the actual weight of feeding stuffs 

 required to constitute a maintenance ration, as well as the 

 quantities of metabolizable energy contained in it, will vary 

 with the kinds of feeds used has already been pointed out 

 (375) and is indeed sufficiently obvious. 



The maintenance requirement of sheep 



382. Metabolizable energy in maintenance rations. Data 

 regarding the maintenance ration of sheep are much less abun- 

 dant than those for cattle and no experiments have been re- 



1 Jour. Agr. Research, 3 (1915), 484-485. 



2 Mo. Expt. Sta., Research Bui. 7, p. 120. 



3 U. S. Dept. Agr., Farmers' Bui. 346, p. 15. 



