STATICS 137 



rations calculated by means of the formula (p. 128) correspond 

 to 164 Ibs. of hay for the former and 133 Ibs. for the latter 

 a difference of 31 Ibs. 



When the live weight of the animals does not vary more 

 than about 10 per cent, from that on which the feeding 

 standard is based, the error would be, perhaps, negligible ; 

 but when the variation amounts to 50 or 100 per cent., i.e. 

 when the actual live weight of the animals is only half or 

 is double that assumed, the error would be more considerable. 



In order to obtain accurate results, it would be necessary, 

 in the case of oxen, to have a different feeding standard for 

 each 100 Ibs. or so of live weight from about 500 Ibs. up to 

 2000 Ibs. Such multiple feeding standards are never given 

 for oxen, but they are generally considered necessary in other 

 cases. Thus, different feeding standards are given for pigs 

 of 50 Ibs., 100 Ibs., and so on, up to 300 Ibs., live weight. 

 The quantities of nutrients are, however, usually stated as 

 per 1000 Ibs. live weight in each case. For example, if the 

 feeding standard for pigs of 50 Ibs. live weight be 6*6 Ibs. 

 of protein, and 30 Ibs. of non-nitrogenous nutrients per 1000 

 Ibs. live weight, then the quantities per head would be 

 0*33 Ib. of protein and 1*5 Ibs. of non-nitrogenous nutrients. 

 For ten such pigs the quantities would be 3*3 Ibs. of the 

 former and 15 Ibs. of the latter. It is assumed, of course, 

 that all the ten pigs are approximately of the same weight. 

 If they were not, the feeding standard would not be applic- 

 able even though the sum of the live weights amounted to 

 TOOO Ibs. 



The deductions from experiments on fattening animals, 

 milk cows, and working horses, have also been expressed in 

 the same form. Such feeding standards include the amounts 

 of nutrients required for the simple maintenance of the 

 animals as well as those required specially for fattening, milk 

 production, and work. They are, in fact, theoretically, the 

 sum of the two quantities. They are, therefore, subject to 

 the same limitations as the feeding standards for maintenance, 

 and there are other circumstances, peculiar to each case, which 

 render them even more unreliable. These circumstances 



