NUTRITIVE RATIO OF FOOD. 103 



cause of ill-health or at least want of vigour in horses, which 

 in such a case will evince their craving for the substances 

 of which they are in need, by licking the plaster off walls, 

 eating dirt, and preferring muddy water to clean water to 

 drink. 



We learn from the experiments made by Henry on growing 

 pigs, that an addition of bone meal to the food greatly increases 

 the strength of the bones. A similar result, though to a lesser 

 extent, was arrived at by an addition of wood ashes. These 

 experiments lasted from 84 to 128 days. In 112 days, 

 two pigs consumed 10^ Ib. of bone meal and 7^ Ib. of 

 salt ; and in the same time, two other pigs consumed 33 Ib. of 

 hard wood ashes and 8 Ib. of salt. 



Attention may with advantage be directed to the fact to 

 which I have tried to give prominence in the foregoing pages, 

 that the quality of the muscles, tendons, ligaments, bones, fat, 

 and other tissues greatly varies according to the food upon 

 which an animal is fed. Although we all know that this is 

 the case in butcher's meat, some are inclined to think that 

 for working purposes " bone is bone " and " muscle is 

 muscle," whatever has been the food upon which they have 

 been produced. 



NUTRITIVE RATIO OF FOOD. 



The " nutritive ratio " of a food is the term used to express 

 the proportion which exists between the nitrogenous matter of 

 the food and the other energy-producing constituents, namely, 

 the starch, sugar, and fat. As fat is calculated to possess 2.3 

 times the energy-giving properties of sugar and starch, the 

 weight of the fat is multiplied by 2.3. Thus, taking the 

 analysis of oats given on page 62, we find that the nutritive 

 ratio of that grain is 



11.3 to 57-3 + 5-4 X2.3 

 i to 6. i (about). 



