362 NUTRITION OF FARM ANIMALS 



ration of such an animal must supply an amount of net energy 

 equal to the maintenance requirement plus the quantity of 

 energy contained in the gain made. The latter quantity, how- 

 ever, may be computed approximately from the data given in 

 i regarding the chemical composition of the increase in live 

 weight during fattening. Estimating the energy content of 

 protein at 2586 Cals. per pound (5.7 Cals. per gram) and that 

 of fat at 4309 Cals. per pound (9.5 Cals. per gram), the energy 

 content of one pound of increase was as shown in the last col- 

 umn of Table 65 (442). 



Excluding two apparently questionable results, 1 the range 

 and average of the remainder are as follows. Although some- 

 what variable they indicate that on the average of an entire 

 fattening period a pound of increase in live weight in cattle, 

 sheep and swine is equivalent to about 3.25 Therms. 



TABLE 73. ENERGY PER POUND INCREASE IN LIVE WEIGHT 



Maximum 4.002 Therms 



Minimum 2.485 Therms 



Average 3- 2 45 Therms 



452. Influence of stage of fattening. The results just cited 

 are in most cases those of an entire fattening period. There 

 can be little doubt, however, that the composition of the in- 

 crease and its energy content vary materially as the fattening 

 advances. 



This appears clearly from Henneberg, Kern and Wattenberg's re- 

 sults upon sheep. The "fat" animal had been fed for 10 weeks and 

 was regarded as fat according to local standards. The "very fat" 

 animal had been fed for 29 weeks, or until no further gain in live 

 weight occurred. As the table shows, the total gain by the "very 

 fat" animal contained materially lower percentages of water, ash 

 and protein and a higher percentage of fat, and had a 10 per cent 

 higher energy content than the gain by the "fat" animal, while a com- 

 parison between the "fat" and the "very fat" animals shows the 

 gain made by the latter during the last 19 weeks of fattening to have 



1 Pfeiffer and Friske's results appear exceptional, since the gain apparently con- 

 sisted to an abnormally large extent of water, while the authors themselves point out 

 that the gains of dry matter were notably less than should have been produced from 

 the feed consumed. It would seem, therefore, that their omission is justified. Soxh- 

 let's result upon swine No. i has also been omitted for a similar reason. 



