296 



NUTRITION OF FARM ANIMALS 



on the various rations is computed from the results of five previous 

 balance experiments on similar rations by combining them in various 

 ratios according to the proportions of oats, hay and straw consumed. 

 From this is subtracted the heat computed to have been produced in 

 the digestion of the feed (not including the work of mastication), 

 the remainder showing, of course, the katabolism due to internal 

 work, i.e., the net energy requirement. 1 



Table 51 shows for the eight experiments compared the 

 total estimated heat production per day, the computed energy 

 expenditure caused by the consumption of the feed, and by dif- 

 ference the energy expenditure in the fasting state, i.e., the net 

 energy requirement for maintenance. 



TABLE 51. NET ENERGY REQUIREMENT FOR MAINTENANCE OF HORSE 



In the experiments with a standard ration of 6 kgs. of oats, 

 one of straw, arid six (or seven) of hay, the average computed 

 fasting katabolism per day in three winter periods was 4.33 

 Therms, while in a single summer period it reaches the minimum 

 of 3.97 Therms per head, or 4.08 Therms per 1000 pounds live 

 weight. Zuntz and Hagemann consider that the latter amount 

 represents approximately the minimum requirement for the in- 



1 For a more complete account of the method, compare the writer's Principles 

 of Animal Nutrition, pp. 386-387. 



