FEEDING OF ANIMALS. 265 



1. The sources in the food of the fat produced in the incidental 

 animal body. questions ' 



2. The characteristic demands of the animal body (for 

 nitrogenous or non-nitrogenous constituents of food) in the 

 exercise of muscular power. 



3. The comparative characters of animal and vegetable 

 foods in human dietaries. 



Food Consumed and Increase Produced. 



It is proposed, first, to consider the results illustrating the 

 amounts of food, and of its nitrogenous and non-nitrogenous 

 constituents respectively, consumed by a given live-weight of 

 animal within a given time, and the amounts required to 

 produce a given amount of increase in live -weight. The 

 illustrations will be drawn from experiments with sheep and 

 with pigs. 



The Experiments vnth Sheep. 



Table 67 (p. 266) shows, for each of three series of experi- Quantity 

 ments with sheep, in the first three columns the amounts of f n {° e °^ s ^ 

 nitrogenous, of non-nitrogenous, and of total organic substance, sheep, 

 consumed per 100 lb. live-weight per week, and in the last three 

 columns the amounts consumed to produce 100 lb. increase in 

 live-weight. The figures represent the quantities of the crude 

 constituents consumed — that is, the amounts of nitrogenous 

 substance calculated by multiplying the nitrogen by 6.3, 

 which implies that the whole of it exists in the foods as 

 albuminoids, which admittedly is not the case. It will be Table 67 

 seen, however, that this method is quite sufficient for the ex P^ ained - 

 purposes of the illustrations at present in view, though it is 

 frequently far from accurate in the case of unripened vege- 

 table products ; and it is especially so in that of succulent 

 foods, such as feeding roots. The amounts of crude non- 

 nitrogenous substance are calculated by deducting those of 

 the mineral matter, and of the crude nitrogenous constitu- 

 ents, from those of the total dry matter consumed. Here 

 again, it is admitted that the results are only approximations 

 to the truth ; but it will be seen that, as in the case of the 

 nitrogenous constituents, they are nevertheless quite sufficient 

 for the purposes of our present illustrations. The crude total 

 organic matter is simply the sum of the nitrogenous and non- 

 nitrogenous calculated as above. 



Referring to the results, it is impossible to go into any Expiana- 

 detail here. A glance at the figures in the first three columns t ™J$ s 

 of the Table (67) relating to the amounts of the constituents 

 consumed per 100 lb. live-weight per week is sufficient to show 



