126 THE CHEMISTRY OF THE FARM. 



plainly appears from the lower division of the table. The 

 pig, with its very large consumption of food, has, in fact, 

 to spend a smaller proportion of it on heat and work, and 

 has thus a larger surplus left to store up as increase. Of 

 100 Ibs. digested organic matter, the fattening ox spends 

 about 77 for heat and work, the sheep 74, and the pig 57. 

 The upper division of the table shows, however, that in a 

 given time and for the same body weight, the pig appro- 

 priates a larger amount of food to heat than the sheep, and 

 the sheep more than the ox. This is probably due to the 

 greater loss of heat from the bodies of small animals (see 

 p. 119), which in the pig is intensified by the slight cover- 

 ing of hair upon its skin. The pig, with its rapid feeding, 

 and high rate of increase, is undoubtedly the most econ- 

 omical meat-making machine at the farmer's disposal. 



The results given by sheep are seen to lie in nearly 

 every case between those given by oxen and pigs, being 

 however much nearer to the former than to the latter. 

 The German experiments place the sheep below the ox 

 as an economic producer of increase, instead of above it, 

 as in the Rothamsted statistics just quoted ; the difference 

 is probably due to the different breeds of animals experi- 

 mented with. The results relating to manure will be 

 discussed in the next chapter. 



We have hitherto looked at the fattening period as a 

 whole ; the rates of consumption and of increase are, how- 

 ever, very different in different stages of this period. 



As a fattening animal increases in size the quantity 

 of food it consumes also somewhat increases, the stomach 

 at the same time becomes larger. When the animal 

 becomes very fat the consumption of food falls off again, 

 and the rate of increase at this point is much diminished. 



