MAINTENANCE RATIONS OF HOESES. 



61 



of the energy of the digested matter by the use of the factor 3.96 

 calories per gram instead of 4.1 calories per gram. Their compari- 

 son of the two groups gives them by difference 31 per cent as the 

 proportion of the available energy of the digested nutrients which 

 was recovered in the form of work, a percentage corresponding very 

 closely to that found for the work of draft in their experiments, 

 viz, 31.4. Upon this basis, they compute in each group the amount 

 of nutrients required for the total work done and by subtraction 

 the total digestible nutrients required for maintenance. 



Their results for an animal weighing approximately 500 kilograms 

 are as follows, the equivalent metabolizable energy being obtained 

 by the use of Zuntz and Hagemann's factor of 3.96 calories per gram. 

 The average does not differ materially from that computed directly 

 from Wolff's later experiments. 



Total 

 digestible 

 nutrients. 



Equivalent 

 metaboliz- 

 able energy. 



Periods of light work. . 

 Periods of heavy work 



Average 



Grams. 

 3,776 

 3,763 



Therms. 

 14.95 

 14.90 



3,770 



This result they compare with that obtained by them in a balance 

 experiment with a respiration apparatus from which, as noted on 

 page 56, they compute a maintenance ration of 12.93 therms. 

 Their ration, however, contained notably less crude fiber than did 

 Wolff's rations, the differences being as shown in the following 

 table, which includes also the equivalent digestive work, estimated 

 by Zuntz and Hagemann at 2.65 calories per gram : 





Difference 

 in crude 

 fiber fed. 



Equivalent 

 digestive 

 work. 



Periods of light work 



Grams. 

 974 

 956 



Therms. 

 2.58 

 2.53 



Periods of heavy work 



Average 



965 



2.56 





Subtracting this amount from the average computed from Wolff's 

 experiments leaves a remainder of 12.37 therms as the metabolizable 

 energy which would have been necessary for maintenance had Wolff's 

 rations contained no more crude fiber than Zuntz and Hagemann's. 



Wolff's experiments afford no data for computing in terms of 

 available energy the maintenance requirement in the sense in which 

 this term is used by Zuntz and Hagemann and in the discussion of 

 the maintenance requirements of cattle, on pages 33 to 35, viz, as 



