192 THE CHEMISTRY OF CATTLE FEEDING 



store, half-fat and fat sheep, it will be seen that there is but 

 little increase in the actual amounts of water, nitrogenous 

 matter and ash, and that the increase of live weight consists 

 almost entirely of fat. 



In cases where the increase of live weight is more con- 

 siderable, e.g. those of the extra-fat sheep, and the fat pig, the 

 amounts of water and nitrogenous matter are also seen to be 

 substantially increased. Judging by the mineral matter, it 

 would appear that both animals had grown as well as 

 fattened. A more marked change of the same kind is 

 noticeable on comparison of the lamb and sheep and of the 

 calf and ox. 



We may take it, therefore, that fattening, i.e. the change 

 from the store to the fat condition, as apart from growth, 

 consists mainly in the deposition of fatty tissue. As a matter 

 of fact, other experiments tend to show that the additional 

 nitrogenous matter and water found in the fat animal are 

 mainly in the blood, and very little, if any, in the permanent 

 non-fatty tissue. 



When a young animal grows, all the constituents are 

 increased in quantity, both fat and non-fatty tissue being 

 deposited. When an animal grows and fattens at the same 

 time, both changes occur simultaneously. The amounts of all 

 the constituents are increased, but the increase of fat exceeds 

 that of the others. 



The rate of increase in fattening depends largely upon the 

 age and condition of the animals. It is much more rapid 

 during the earlier than in the later stages. The weight of an 

 animal which is growing as well as fattening naturally 

 increases much more rapidly than that of one which has 

 already attained its full growth. But apart from this, great 

 differences are observed in the rate of fattening increase not 

 only as between animals of different kinds and breeds, but 

 even between individuals of the same parentage, under similar 

 conditions as regards food, shelter, etc. 



The data obtained or used in the Rothamsted experiments 

 are of peculiar interest in this connection. Some of them are 

 given in the following table. 



