FEEDING OF ANIMALS. 283 



for curing will, however, probably contain lower percentages 

 of nitrogenous substance, but higher, and sometimes consider- 

 ably higher, percentages of both fat and total dry substance. 

 The tendency of the demand in recent years has, however, 

 been for less excessively fat bacon than formerly. 



Thus far, then, it has been shown that the amounts of food, Nitrogen- 

 ox of its various constituents, consumed, both for a given live- ° n u s n ^ ro . 

 weight of animal within a given time, and to produce a given genous sub- 

 amount of increase, were very much more dependent on the sta ™ es °f 

 quantities of the non-nitrogenous, than on those of the nitro- increase in 

 genous constituents, which the food supplied. It has been h ™-weight. 

 said, that when the large requirement for non-nitrogenous 

 constituents of food to meet the expenditure by respiration is 

 borne in mind, it need not excite surprise that consumption 

 in relation to a given live-weight within a given time should 

 be so largely measurable by the amount of digestible and 

 available non-nitrogenous substance which the food supplies ; 

 but that, at first sight, it was less intelligible that the quan- 

 tities consumed to produce a given amount of increase in live- 

 weight should also be much more dependent on the supplies 

 of the non-nitrogenous, than on those of the nitrogenous, 

 constituents of the food. 



The results relating to the chemical composition of the dif- Proportion 

 f erent animals, in different conditions as to age and maturity, °ff at and 



. , . 7 ° J ' nitrogenous 



nave shown, however, that even store animals may contain as matter in 

 much, or even more, of the non-nitrogenous substance — fat — the ?°. m ' , 

 than of nitrogenous substance ; whilst the bodies of fattened animals. 

 animals may contain two, three, four, or even more times as 

 much dry fat as dry nitrogenous matter. It has further been 

 shown, that the proportion of fat to nitrogenous substance in 

 the increase in live-weight of the fattening animal, is much 

 higher than in the entire bodies of the fattened animals. If, 

 therefore, the non-nitrogenous substance of the increase — the 

 fat — is derived from the non-nitrogenous constituents of the 

 food, the relatively large demand for such constituents for the 

 production of fattening increase, would seem to be amply 

 accounted for. 



The important question arises, therefore, What are the Animport- 

 sources in the food of the fat of the fattening animal ? In <%&*"*' 

 other words, from what constituent or constituents in the 

 food is the fat produced ? 



