86 NUTRITION OF FARM ANIMALS 



is enormously developed in the horse, having about 45 per cent 

 of the total capacity of the digestive tract, and serves, like the 

 ccecum, to continue the digestion of the less soluble portions 

 of the feed. 



123. The pancreas. In the stomach, the glands which 

 secrete the gastric juice are located in the mucous lining of the 

 organ. In the case of the intestines, the glands which supply 

 the various digestive juices, like the salivary glands of the mouth, 

 lie in part entirely outside the alimentary canal proper. One 

 of the most important of these is the pancreas. This is a large 

 gland located near the stomach, liver and duodenum, its duct 

 opening into the latter either by a common exit with that of the 

 bile duct (horse, sheep), or somewhat lower down (cattle, swine). 

 The secretory action of the pancreas, like that of the salivary 

 and gastric glands, is intermittent, the gland being active only 

 when feed is present in the duodenum. 



The pancreatic juice is a clear, viscid liquid, having an al- 

 kaline reaction due to its content of sodium salts. It contains 

 in the neighborhood of eight to ten per cent of solid matter and 

 has a specific gravity of approximately 1.030. It differs from 

 other digestive juices in containing a relatively large amount 

 of protein. As in the case of all the other digestive fluids, the 

 essential active ingredients are enzyms, of which the pancreatic 

 juice contains three in particular, viz., a protease, trypsin, acting 

 upon the proteins, an amylase, amylopsin, acting upon starch, 

 and a lipase, steapsin, acting upon fats. Small amounts of 

 chymosin and of a lactase have also been found. In the juice 

 as secreted by the pancreas, the trypsin at least, if not the other 

 enzyms, exists in the form of a pro-enzym, trypsinogen, which 

 is converted into trypsin (" activated ") after the secretion 

 reaches the duodenum. 



124. The liver. This, the largest gland in the body, is 

 located immediately below the diaphragm and lies chiefly on 

 the right side of the body. It is relatively small in ruminants 

 and large in the hog. 



The liver has other important functions in nutrition, as will 

 appear in Chapter V, but as related to digestion it secretes the 

 bile. This fluid, produced by the hepatic cells, passes from 

 them into the bile capillaries, which unite to form small ducts, 

 the latter finally coalescing and constituting the bile duct. In 



