26 FEEDS AND FEEDING 



absorbed in large quantities. If the large intestine is not functioning 

 properly and the contents remain an undue time, excessive putrefaction 

 may take place, injuring the animal thru the absorption of the poisonous 

 products formed. 



46. Special provision for the horse. The horse, tho eating coarse food 

 like the ox, has a small stomach and no paunch for specially preparing 

 such food for digestion. In partial compensation, the caecum and large 

 colon, parts of the large intestine, are greatly enlarged, as has been 

 previously pointed out. (35) The incompletely digested matter from the 

 small intestine, together with the enzymes mixed with it, pass into the 

 caecum. Here the enzyme action continues, and the cellulose of the feed 

 is also attacked and digested by bacteria, as in the paunch of ruminants. 

 Due to this, the horse is able to digest such feeds as hay and straw quite 

 thoroly, tho less completely than do cattle and sheep. The caecum of 

 other farm animals is relatively small and unimportant in digestion. 



47. Digestion of fat. Since the steps by which the food is prepared 

 thru digestion for final use by the body are so numerous and complicated, 

 it is well now to review the subject, dealing with the nutrients and what 

 occurs with them, rather than considering the organs and solvents 

 employed. 



As has been stated, the fats of foods, no matter how finely divided, 

 cannot directly enter the circulation, but must be changed in the follow- 

 ing manner: One of the enzymes produced by the pancreas is the fat- 

 splitting lipase, which breaks some of the fats in the food into glycerin 

 and fatty acids. The bile is largely made up of alkaline salts, and with 

 these the fatty acids react and form soaps. These soaps in turn form an 

 emulsion with the unchanged fats, the emulsified fats presenting a large 

 surface on which the lipase may act. Thus, it is believed that the fat 

 which is finally absorbed is split into glycerin and fatty acids, the latter 

 and the alkalies of the bile forming soaps. These soaps and the glycerin 

 are absorbed by the intestinal wall, in the cells of which they are reunited 

 into fats. Some authorities believe, however, that a part of the fatty 

 acids and glycerin formed by the splitting of neutral fats by lipase may 

 be absorbed as such, without being first changed to soaps. 



48. Carbohydrate digestion. The digestion of either starch or sugars 

 (other than those of glucose-like form) consists in converting them into 

 glucose or glucose-like sugars, which are the only forms of carbohydrates 

 that can be used in the body. Since these carbohydrates constitute a 

 large portion of the food of animals, Nature provides for their digestion 

 in several parts of the alimentary tract. Carbohydrate digestion begins 

 with the action of the ptyalin of the saliva, which splits starch into 

 maltose. Ptyalin action continues in the first portion of the stomach, 

 but ceases in the latter part of that organ. Nearly all the carbohy- 

 drates are carried on from the stomach into the small intestine, which 

 is the principal organ concerned in their final digestion. Here the 

 starches which have escaped digestion in the mouth and stomach are 



