J. Alan Murray 157 



could easily be allowed for in his empirical estimate of the animal's 

 requirements for maintenance. 



Six pounds of Kellner's starch equivalent corresponds to about 

 20 lb. of hay of average quality. This estimate of the requirements 

 for maintenance of a 1000 lb. ox does not differ materially from that 

 of Wolff 1 and the older authorities, and the author has hitherto regarded 

 it as "the generally accepted ration." It is, however, very different 

 from that of Wood and Yule, which corresponds to only about 13 lb. 

 of such hay. This discrepancy cannot be lightly passed over. It is 

 too considerable, and it is of fundamental importance in regard to this 

 and other investigations. If they adhere to their statement it would 

 be interesting to know upon what data it is founded. It is to be hoped 

 that they will take an early opportunity of clearing up the matter. 



It is of course possible that Wood and Yule did not intend to propose 

 a standard radically different from that of Kellner and Wolff. The 

 omission from their formula of all reference to the "value" of the 

 food may be merely a typographical error, but the statement that an 

 ox of 1000 lb. live weight when oi\ maintenance diet evolves 10,800 

 Cal. of heat per day seems to preclude this explanation. It is evident 

 that this statement is not based upon a direct determination in the 

 calorimeter, but that 10,800 Cal. is merely the calculated equivalent 

 of G-35 lb. of pure starch. It may be inferred therefore, that the formula 

 was intended to include the whole of the available energy of the food 

 and not the dynamic portion only. The only obvious way of escape 

 from this conclusion is to assume that the statement involves a repetition 

 of Kellner's mistake in calculating the amount of heat an animal should 

 evolve from the starch equivalent instead of from the total available 

 energy of the food. He says^ that "an ox weighing 600 Kg. requires 

 a daily supply of 12,780 Cal." ; but as this corresponds to about 10,620 

 Cal. for an ox of 1000 lb. it is clearly inconsistent with the ration pre- 

 scribed in the tables. The latter, quoted above, represents from 14,500 

 to 18,350 Cal. per day of available energy, and this accords well with 

 the estimate on the next page: "For nuiintenance of the animal 

 determined from other experiments — 17,320 Cal." 



It has hitherto been customary to assume that the requirements 

 for maintenance of oxen were proportional to the live weights of the 

 animals and could therefore be determined by rule of three, though 

 it has long been known that this is not true. A notable advance has 



' Frirm Fooih (p. .350). Gurney and Jackson, 1895. 

 - The Sciciilific Feeiliiig of Animals, p. 48. 



