164 THE CHEMISTRY OF CATTLE FEEDING 



In the absence of exact information regarding the size of 

 the horses or the amount of work done by them, it is 

 difficult to compare these rations or to criticise them. Two 

 things, however, are evident, viz. (i) the proportion of 

 protein to energy accords fairly well with the conclusions 

 arrived at (p. 160) ; (2) if the conditions are at all com- 

 parable, then either Ration I. is excessive or the other two 

 are inadequate. 



Maintenance rations for horses of different sizes may be 

 calculated by means of the formula (p. 128) as follows : 



Live weight of animal 1000 1500 2000 Ibs. 

 Thermic energy required 35 46*5 56*8 kt. 



The thermic energy of the coarse fodder in Ration I. is 

 suitable for horses of noo to 1200 Ibs., in Ration II. for 

 horses of 900 to 1000 Ibs., and in Ration III. for horses of 

 700 to 800 Ibs. live weight. These would hardly be described as 

 "large farm horses." The inference is that the coarse fodder 

 is not by itself sufficient for maintenance, and some of the 

 energy of the finer and more expensive foods must, therefore, 

 be devoted to this purpose. In that respect the rations are 

 not of the most economical character. 



Large horses would presumably be required to do heavy 

 work, for which large amounts of dynamic energy are required. 



Work (million foot-pounds) . . 12 14 16 

 Dynamic energy required (kt.) . 27*5 32*1 36-6 



The dynamic energy of Rations II. and III. is more than 

 sufficient for the hardest work, but it is probable that horses 

 of less than 1000 Ibs. live weight could not do so much work 

 in a day. If they did only 14 million foot-pounds of work, there 

 would be a certain balance of energy which when added to 

 the maintenance ration would make that suitable for horses of 

 1 200 Ibs. live weight. Ration I. provides enough thermic 

 energy for horses of this size, and much more dynamic energy 

 than is required for the hardest work. This ration must, there- 

 fore, be deemed excessive unless the horses were very much 

 larger than the others, and in that case it is uneconomical. 



