110 VETEEINAEY HYGIENE 



substances to be digested. Excessive work may cause a 

 slight decrease in the amount digested. 



Different Kinds of Animals. — No important difference is 

 observed in the amount of forage digested by oxen, cows, 

 sheep or goats. Oxen digest hay rather better than sheep, 

 while sheep digest clover hay rather better than oxen, so 

 that compensation occurs. 



Horses, on the other hand, digest less hay than rumi- 

 nants, this reduction being confined to the fat, carbo- 

 hydrates, but particularly the cellulose. Of the total 

 nitrogen free matters in hay, the horse digests 20 to 25 per 

 cent, less than ruminants. 



Individuality. — -This exercises a marked effect on digesti- 

 bility. Apart from age, defective teeth, and weakened 

 digestion, animals of the same species, breed and age, may 

 show differences in digestive power amounting to from 

 2 to 4 per cent, of the dry matter in food. 



Effect of Corn added to Hay. — This produces under ordi- 

 nary circumstances no effect on the digestion of hay, pro- 

 vided an albuminoid ratio of 1 : 5 or 1 : 6 is maintained. 

 A ' depression ' in digestibility is observed when the ratio 

 falls to 1 : 7 or 1 : 8. 



Eff'ect of Starch added to Hay. — Large quantities of carbo- 

 hydrates reduce the digestibility of both the proteids and 

 cellulose in hay, and this holds good for all animals. This 

 ' depression ' in digestibility is not considerable until the 

 carbo-hydrate amounts to 25 or 80 per cent, of the total 

 dry matter in the hay, though it is much greater if straw 

 forms part of the diet. This depression can be removed 

 by the addition of nitrogenous food, in other words, by 

 raising the albuminoid ratio. 



These observations show how necessary it is in the feed- 

 ing of cattle, to avoid the excessive use of ' roots ' with 

 fodder, excepting the total nitrogen in the diet be raised. 



The addition of oil to a diet does not increase the amount 

 digested, this is important in the face of the common prac- 

 tice of adding hnseed oil to the food of horses out of con- 

 dition. If the fat given be part of the food, as in linseed, 



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