444 Mr. J. B. Lawes and Dr, Gilbert on the & 



ources 



Lastly, the proportion of fat, whether reckoned in relation to 

 the total weight of the body, or to the weight of the increase 

 whilst fattening, is greater in the sheep than in the ox, and 

 greater still in the pig. 



Whilst referring to the connexion between the weight and 

 capacity of the stomach and the character of the food, it will not 

 be without interest to call attention to the gradation in the pro- 

 portion from the ox to the sheep, from the sheep to the pig, and 

 from the pig to man. Below is given the approximate average 

 proportion of stomach, by weight, in 100 live-weight of each. 



Oxen. • Sheep. 



Pigs. 



Man. 



3-19 2-44 



0-S8 



0-38 



Without assuming that relative weight represents with nume- 

 rical exactitude relative capacity or size, w T e nevertheless cannot 

 doubt that these figures have a very obvious significance. Thus, 

 the ox consumes the largest proportion of difficultly digestible 

 or indigestible woody-fibre, the sheep less, the pig scarcely any, 

 but a much larger proportion of comparatively easily digest- 

 ible starch, w T hilst nian, within certain limits, the better he is 

 fed the less does the non-nitrogenous portion of his food consist 

 of starch, and the more of the much more highly concentrated 

 alimentary substance fat, produced for him from much less con- 

 centrated vegetable food-materials by the animals which he feeds 

 for his own consumption. 



From the facts which have been briefly stated, it will be obvious 

 that, of the most important animals which we feed for human 

 food, the pig offers many advantages as a subject for the consi- 

 deration of the source in the food of the fat which he yields. 

 Thus, for a given live- weight he comprises a comparatively small 

 proportion of alimentary organs and contents, and he consumes 

 a large proportion of food, and yields a large proportion both of 

 total increase and of fat, within a given time; his food is, as 

 such, of a high character, yielding, compared with that of oxen 

 or sheep, for a given weight of it much more total increase, much 

 more fat, and much less excreted and necessarily effete matter ; 

 whilst his proportion of fat is the greatest, both in a given live- 

 weight and in his increase whilst fattening. It results that 

 changes in his live-weight are in a much less degree likely to be 

 influenced by variation in the amount of the contents of the 

 stomach and intestines, and are therefore much more direct 

 indications of real increase of the substance of the body, and 

 hence that there is much less probable range of error in calcu- 

 lating the amount and composition of the increase in live-weight 

 in relation to the amount and composition of the food consumed. 



