CHAPTER VIL 



FOODS. 



The Composition of Foods. — Detailed composition — Proportion of nitrogen 

 existing as true albuminoids — Variation in foods due to age and 

 manuring — Proportion between nitrogenous and non-nitrogenous 

 constituents — Ash constituents. Digestibility of Foods. — Method of 

 determination — Experiments with ruminants — Influence of age of 

 animal, daily ration, and labour — Influence of the maturity of fodder 

 crops on their digestibility — Influence of one food on the digestibility 

 of another — Common salt — Experiments with horses — Experiments 

 with pigs — Experiments with geese. Comjyarative Nutritive Value 

 of Foods. — Influence of proportion of water — Comparative heat and 

 work producing power— Proportion of albuminoids to non-albuminoids 

 — General conclusions. 



In the preceding chapter we have enumerated the chief 

 constituents of food, and described their functions in the 

 animal body ; we may now proceed a step further, and 

 consider the detailed composition and feeding value of 

 the foods actually employed on the farm. 



The nourishing value of a food is plainly fixed by two 

 factors : — 1. Its composition. 2. Its digestibility. The 

 first of these determines the character of the food — its 

 richness in albuminoids, fat, carbo-hydrates, and ash con- 

 stituents. The second determines the extent to which these 

 various constituents are made use of in the animal body. 



Composition of Poods. — The average percentage com- 

 position of the foods commonly given to farm animals is 



