84 THE CHEMISTRY OF THE FARM. 



composition and digestibility are largely influenced by 

 their age and condition when cut. The young plant is 

 always the most nutritive. 



The superior fattening quality of a pasture, as compared 

 with that of the hay made from it, is clearly due to the 

 fact that on land continuously grazed the animal is entirely 

 fed on young herbage, while hay will always consist of the 

 fully grown plant. 



Fodder crops do not sensibly diminish in digestibility 

 by being made into hay, if haymaking is carefully carried 

 out in good weather. But the loss of the finer parts of 

 the plant by rough treatment, or the washing out of 

 soluble matter by rain, may considerably diminish the 

 digestibility. Hay appears to lose some of its digestibility 

 by keeping. 



We now turn the influence of one food on the disresti- 



o 



bility of another. 



If to a diet of hay and straw, consumed by a ruminant 

 animal, a pure albuminoid, as wheat gluten, be added, the 

 added food is entirely digested without the rate of diges- 

 tion of the original food being sensibly altered. The same 

 result has been obtained in experiments with pigs. These 

 animals were fed on potatos, to which variable quantities 

 of meat flour were afterwards added. The albuminoids of 

 the meat were entirely digested, while the proportion of 

 the potatos digested remained unchanged. 



An addition of oil (olive, poppy, and rape oil) to a diet 

 of hay and straw is also apparently without unfavourable 

 influence on the rate of digestion ; indeed some experi- 

 ments with small quantities of oil (^ lb. of oil per day per 

 1000 lb. live weight) show an improved digestion of the 

 dry fodder. With large additions of oil the appetite of 



