136 THE CHEMISTRY OF CATTLE FEEDING 



(1) Multiply the quantities of the several constituents by 

 their thermic values, and the sum of the products will be 

 found to amount to 35 kt. Thus 



Protein ' .. ' . 075 x 4-93 = 3-69 



Fat O'i5x8'5o= 1-27 



Carbohydrates 8*00 X 376 = 30-08 



35-04 kt. 



(2) By the reverse method 



Deduct the thermic energy of the protein from the total, 

 35 (o'75 X 4'93) = 3i'3i kt. 



Divide the balance by the available energy of the starch, 

 S 1 '^ 1 -r3' 7 6 = 8-33 Ibs. starch. 



The feeding standard in terms of nutrients, therefore, is 

 075 Ib. of protein and 8*33 Ibs. of carbohydrates, or 8 Ibs. 

 of carbohydrates and 0*15 Ib. of fat. 



It is a matter of indifference in which of the two forms 

 the feeding standard is expressed. In the author's opinion 

 it is more convenient to state it in terms of protein and of 

 available thermic energy instead of pounds non-nitrogenous 

 nutrients ; for, after all, the latter merely represents so much 

 energy. 



The method of stating the quantities as per 1000 Ibs. live 

 weight is open to more serious objection ; for it is usually 

 held to imply that the quantities required by animals (of the 

 same kind and condition) of any other weight can be calcu- 

 lated by rule of three. But it has been shown (p. 127) that 

 the requirements of the animals are not directly proportional 

 to their mass. The rule of three cannot, therefore, be used, 

 and the feeding standards cannot be properly applied to 

 animals that are not of the size assumed. 



For instance, the total weight of a group of five oxen 

 having an average live weight of 1600 Ibs. per head would be 

 exactly the same as that of a group of ten having an average 

 live weight of 800 Ibs. per head. According to the customary 

 methods of using feeding standards, the daily rations should 

 be exactly the same for each of the groups, viz. about 153 Ibs. 

 of hay. This quantity would, however, be too little for the 

 smaller animals and too much for the larger ones. The 



