198 THE CHEMISTRY OF CATTLE FEEDING 



animals generate more heat than those in store condition. 

 The process of fattening apparently involves additional 

 internal work, more food is oxidised, and the resulting 

 energy appears as heat. The amount of the maintenance 

 ration may, therefore, be somewhat reduced, or more readily 

 digestible food may be substituted for a portion of it. Other- 

 wise heat may be developed more rapidly than it is given off, 

 and in hot weather the animals become uncomfortably warm, 

 and the process of fattening is retarded. 



On the average, oxen do not store up as body fat more 

 than about 60 per cent, of the fat, or equivalent quantities 

 of other nutrients, in the food. Sheep, apparently, store up 

 more probably about 75 per cent. and pigs not less than 

 about 90 per cent. In the case of pigs, the question is com- 

 plicated by the fact that they are generally fattened while still 

 growing. The rate of increase is, therefore, very rapid, but 

 the composition of this increase is not exactly the same as 

 that assumed above. It is probably true, however, that pigs 

 store up a larger proportion of the nutrients of the food as 

 true fattening increase than do the ruminants. 



The amount of protein in the fattening increase is relatively 

 small. If, however, the allowance of protein in the food were 

 limited to what is actually stored up as such in the animal's 

 body, the digestibility of the other nutrients would be depressed 

 and waste of food would result. The minimum appears to 

 be about i part of protein to 10 parts of non-nitrogenous 

 nutrients reckoned as starch, i.e. about 2 J times the proportion 

 in which it occurs in the fattening increase. 



Fattening Oxen. In the case of oxen, each pound of 

 fattening increase, it is estimated (p. 189), contains 0*077 Ib. 

 of protein, and o'66 Ib. of fat. But as only 60 per cent, of 

 the fat (or its equivalent) in the food is stored up as body fat, 

 i 'i Ibs. of fat, or equivalent quantities of other nutrients, e.g. 

 2 "7 5 Ibs. of starch, are required to produce each pound of 

 increase. To this must be added 0*08 Ib. of protein, which is 

 also retained as such, and an allowance of about 5 per cent, for 

 loss in the work of digesting the food. Hence it appears that 

 about 3 Ibs. of total digestible nutrients, reckoned as starch, 



