i88 THE CHEMISTRY OF CATTLE FEEDING 



the first step is to determine, as nearly as possible, the 

 nature of the substances of which the increase is composed, 

 and the amount of each constituent in it. 



The method of investigation is, broadly, much the same 

 in all cases, and may be illustrated as follows. The increase 

 is always made up of substances which may be classed as 

 water, ash, nitrogenous matter and fat ; and, for the present, 

 we need only concern ourselves with the last two. What we 

 have to consider is the relative proportions and actual 

 amounts of each. 



Suppose that a calf at birth weighs 60 Ibs., and that on 

 analysis it is found to contain 16 per cent, of nitrogenous 

 matter and 14 per cent, of fat, the remainder 70 per cent. 

 being ash and water. The total increase (60 Ibs.) therefore 

 contains 9-6 Ibs. of the former, and 8-4 Ibs. of the latter 

 substance. As the average period of gestation is about 40 

 weeks say 280 days the nitrogenous matter is deposited at 

 the average rate of 0-034 Ib. per day, and the fat at the 

 average rate of 0*03 Ib. per day, i.e. about half an ounce per 

 day in each case. 



Again, suppose the calf to weigh 60 Ibs. at birth, and to 

 contain 9-6 Ibs. of nitrogenous matter and 8*4 Ibs. of fat as 

 before; and further, that when it is one year old it weighs 

 700 Ibs., and contains 18 per cent, of nitrogenous matter and 

 21 per cent, of fat. Then 700 Ibs. the total live weight of the 

 yearling animal includes [18 X 7 =] 126 Ibs. of nitrogenous 

 matter, and [21 X 7 =] 147 Ibs. of fat. Deduct from these 

 quantities, respectively, the amount of nitrogenous matter 

 (9-6 Ibs.) and of fat (8-4 Ibs.) present in the calf at birth, and 

 we get the amount of nitrogenous matter (n6'4 Ibs.) and of 

 fat (138-6 Ibs.) deposited in 365 days. From this it appears 

 that the former substance is deposited at the rate of 0*32 Ib., 

 and the latter at the rate of 0-38 Ib. per day. 



Lawes and Gilbert's Investigations. In the year 1849, 

 Lawes and Gilbert commenced, at Rothamsted, a series of 

 investigations upon the composition of the bodies of different 

 kinds of farm animals under varying circumstances of age and 

 condition, from the results of which they calculated, in a 



