FOOD 



97 



Digestibility of Food-stuffs, showing the Proportion Digested for 



100 supplied 



Oil in small quantities appears to increase the digestibility of hay and 

 straw, but a large amount causes loss of appetite. Potatoes, owing to the 

 amount of starch they contain, prevent the digestion of hay. Roots have 

 a less depressing effect, owing to the sugar which they contain. 



Col. Smith remarks that in some of his own experiments the addition 

 of 2 lb. of oats to 12 lb. of hay increased its digestibility by more than 

 9 per cent. He adds that, in calculating a diet to ascertain its suitability 

 for an animal, it is necessary to obtain from the tables given a proportion 

 of principles digested, and then to find out the nitrogenous, fatty, and 

 complete nutritive ratios. In illustration of this method of calculation, it 

 is assumed that a horse receives as a daily ration 12 lb. of hay of medium 

 quality and 10 lb. of oats. It is required to know the ratio of this diet 

 before and after digestion, and the proportion of proximate principles 

 digested. 



This information is conveyed in the following table, referring to the 

 constituents of hay and oats. It will be seen that the fat in the hay is 



VOL. III. 



72 



