438 PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



cent., though the carbohydrates are almost completely absorbed, only 

 1 per cent, being lost, and only 5 per cent, of fats escapes absorption. In 

 the herbivora the loss is, however, much greater. Thus, a horse fed with 

 six kilos of oats and fifteen liters of water will pass about twelve kilos 

 of faeces, composed of three kilos of solids, containing 5 per cent, of 

 albuminous matter, 20 per cent, of fat, 20 per cent, of starch, and 60 per 

 cent, of cellulose. If the horse is fed with a mixed diet, composed, for 

 example, of three and a half kilos of oats, five and a half kilos of hay, 

 and one and three-fourths kilos of chopped straw, seventeen kilos of 

 faeces will be passed, in which there will be four kilos of solids, of which 

 30 per cent will be albuminous matter, 40 per cent, fats, 30 per cent, 

 starch, and 60 per cent, cellulose having escaped digestion. The loss 

 is, therefore, greater in a mixed diet than in a horse fed on grain 

 alone. In the ruminants the digestibility^ of hay is much greater than 

 in the horse. Oxen fed with ten kilos of hay will digest and absorb 

 about 50 per cent, of the albuminous matter, while, as already mentioned, 

 if more readily digestible substances are added to the hay diet, less hay 

 will be digested. 



It has been found that in the fermentation of cellulose large quanti- 

 ties of C0 2 and CH 4 are formed, and, as the latter gas is constantly found 

 in the intestine, that its source is in the putrefaction and fermentation in 

 the intestinal canal is readily conceivable, and indicates a possible expla- 

 nation of the fact that about 40 to 60 per cent, of cellulose disappears 

 in the intestinal canal. This may occur in the rumen of the ruminants, 

 while it certainly occurs in the caecum of the horse, although in this 

 animal less cellulose disappears than in the ruminant. 



As regards the inorganic constituents of the food, the fact that the 

 faeces contain but small amounts of soluble salts shows that they must 

 have been largely absorbed. Small amounts only of the alkalies are 

 found in combination with chlorine and sulphuric acid, while potassium 

 and sodium are found in combination as chlorides or sulphates in minute 

 quantities. Magnesium is also almost entirely absent. In the herbivora 

 less lime is absorbed than magnesium, while in the carnivora but very 

 small quantities of both lime and magnesium are absorbed. Another 

 point of contrast between carnivora and herbivora is that in the former 

 almost all the phosphates in the food are absorbed, while in the herbivora 

 they are almost entirely excreted in the faeces, unless they are fed with 

 meal, milk, or other readily digestible food. 



Mr. B. F. Ladd has tested the relative digestibilit}^ of the different 

 feeding stuffs by digestion experiments performed with them, after 

 thorough comminution, with an artificial gastric juice, formed of 0.2 

 per cent, hydrochloric acid with five grammes of pepsin to the liter. 

 The following tables a'ive his conclusions : — 



