FARMER'S CYCLOPEDIA OF LIVE STOCK 



maltose and grape sugar. If the food 

 is in fine particles or has been cooked, 

 the sugar appears within half a minute 

 while otherwise the change from Starch 

 to sugar may not take place for two or 

 three minutes. In ruminants the sugar 

 thus produced is apparently fermented 

 in the paunch giving rise to lactic acid. 

 The saliva also exercises a very slight 

 effect in changing protein into soluble 

 peptones. Fats and oils are not chemi- 

 cally affected by the saliva, but are 

 partly emulsified and thus rendered more 

 susceptible to the action of the gastric 

 and pancreatic juices. 



Action of saliva — I n ruminants the 

 action of the saliva continues in the 

 first three stomachs and is greatly as- 

 sisted by the innumerable bacteria 

 which are taken in the feed and water. 

 The bacteria find in the moisture and 

 warmth of the anterior stomachs ideal 

 conditions for their multiplication. 

 They set up active fermentations which 

 affect starches, sugars, crude fiber and 

 protein. In fact crude fiber is more 

 extensively disintegrated by this fermen- 

 tation than by any of the digestive 

 juices. 



The saliva is active, however, only in 

 alkaline or but slightly acid solutions. 

 The digestion of starches and sugars, 

 therefore, is interrupted as soon as the 

 food reaches the stomach in animals like 

 the horse and pig. The gastric juice is 

 decidedly acid and checks the action of 

 the saliva. 



The gastric juice f all farm animals 

 (in the stomach of the pig and horse and 

 in the fourth stomach of ruminants) 

 contains enzyms, free hydrochloric acid 

 and free lactic acid. These acids check 

 also the fermenting action of the bacteria 

 in the food. Protein is changed into 

 albuminoses and peptones by the pepsin 

 ferment of the gastric juice assisted by 

 the hydrochloric and lactic acids. Some 

 of the albuminous feed stuffs also pro- 

 duce nucleins during digestion. More- 

 over, carbohydrates and coloring matters 

 which are held in some nitrogenous sub- 

 stances may be set free. Certain pro- 

 teids, like casein in milk, are coagulated 

 before digestion takes place. The same 

 process occurs in milk when rennet is 

 added in the manufacture of cheese. 

 The chief digestion products of proteids 

 in the stomach are peptones and albu- 

 minoses. The gastric juice contains also 

 a ferment known as lipase which breaks 

 up the food fats into free fatty acids 



and glycerin. The carbohydrates are 

 not affected by the gastric juice. 



As soon as the partly digested food 

 passes into the intestines the whole mass 

 is rendered alkaline by the addition of 

 bile and pancreatic juice. The bile con- 

 tains also bile acids which unite with the 

 proteids and pepsin causing precipita- 

 tion of the latter. The bile has no 

 effect in breaking up proteids, but acts 

 slightly on carbohydrates and fats, emul- 

 sifying the latter. The movements and 

 secretions of the intestines are greatly 

 stimulated by the bile. In most farm 

 animals the bile and pancreatic juice en- 

 ter the intestine at the same point. In 

 ruminants, however, the pancreatic juice 

 enters lower down. 



The pancreatic juice i s the most active 

 of all digestive fluids. It attacks the 

 proteids actively changing them to pep- 

 tones, albuminoses and other soluble 

 substances. A small amount of insol- 

 uble and, therefore, indigestible nucleins 

 appears as a result of the action of the 

 trypsin in the pancreatic juice. This 

 fluid also has the power of rapidly emul- 

 sifying fats which are further dissolved 

 and saponified by mixture with the bile. 

 Finally the starch which failed to be di- 

 gested by the saliva is almost instantly 

 changed into dextrin, maltose and grape 

 sugar. 



As the food mass passes on through 

 the small intestine the bile and pancre- 

 atic juice continue to act upon it as 

 also the juices secreted by the walls of 

 the intestines. At the same time the 

 bacteria in the food are also active and 

 finally, in the large intestine, gain the 

 ascendency over true digestive ferments 

 and stop the action of the latter. Under 

 the influence of bacteria, especially in 

 the large intestines of ruminants, pro- 

 teids are peptonized, fats split up and 

 carbohydrates changed into lactic, 

 butyric and acetic acids. Even cellu- 

 lose and crude fiber are attacked and 

 partly disintegrated. 



Where the food constituents are di- 

 gested — From the above brief discussion 

 of the digestive processes' it is apparent 

 that protein is digested in the stomach 

 and intestines. Fats are digested by the 

 action of gastric juice, bile, pancreatic 

 and intestinal juices; and carbohydrates 

 by the saliva, pancreatic and intestinal 

 juices. In ruminants cellulose is disin- 

 tegrated partly in the stomach and 

 partly in the colon. The length and 

 capacity of the digestive organs are 

 adapted to the size and feeding habits of 



