FEEDING STANDARDS CALCULATING RATIONS 127 



Second trial ration for maintaining 1,000-lb. steer 



This ration agrees closely with the standard in digestible protein and 

 net energy value. Thus, according to the Armsby standard, a satis- 

 factory ration for maintaining a 1,000-lb. steer may be composed of 

 10 Ibs. corn stover, 6 Ibs. oat straw and 1 Ib. choice cottonseed meal. 



177. Discussion of the net energy systems. The determination of the 

 net energy values of feeding stuffs is an important advancement in our 

 knowledge of the values of different feeds for productive purposes. 

 Owing to the immense amount of labor involved in each such determina- 

 tion, data of this kind can be secured but slowly. In the many years he 

 carried on his very painstaking investigations by means of the respiration 

 calorimeter Armsby was able to complete studies of only 10 individual 

 feeds or concentrate mixtures, several determinations having, of course, 

 been made on each. Thus, the actual net energy values of but few feeds 

 have been determined by Armsby, Kellner, and others. While these 

 values are helpful in estimating the probable net energy values of other 

 feeds not yet tested, such computed results are but approximations. 

 For example, in his earlier table of energy values, Armsby gave a net 

 energy value of 33.56 therms for timothy hay containing 86.8 per ct, 

 dry matter. This value was computed from Kellner 's data. After 

 conducting several respiration experiments in which the actual net value 

 was determined, Armsby found that timothy hay containing the same 

 amount of dry matter had a net energy value of 42.20 therms, or 25.7 

 per ct. more than his former figure. 



Even for the feeds on which experiments have been conducted, the 

 values are far from exact. Not only do different samples of a given 

 feeding-stuff vary in composition (81), but the trials show that the 

 ability to utilize feed, even by animals of the same kind, age, and con- 

 dition, may vary to a greater or less extent. Moreover, the results of 

 both Kellner and Armsby were secured only with steers. Eckles of the 

 Missouri Station 12 has found these values too low when applied to 

 the dairy cow, and Woods 13 of Cambridge University, England, has 

 shown that they are too high for the ox fed a heavy fattening ration. 



Zuntz 14 states that with the horse and pig only a small portion of 



Mo. Res. Bui. 7. "Jour. Sci., 5, 1914, p. 248. 



"Inter. Inst. Agr., Monthly Bui., 5, 1914, No. 4, pp. 435, 446. 



