24 FEEDS AND FEEDING, ABRIDGED 



regular contractions which pass in waves toward the intestinal end. 

 When digestion has progressed sufficiently, as a contraction reaches 

 the rear end of the stomach, the ring of muscles which keeps the 

 stomach shut off from the small intestine relaxes and allows a small 

 quantity of the semi-liquid contents of the stomach to spurt thru into 

 the intestine. After this the ring of muscles again contracts, closing 

 the entrance. The stomach now slowly relaxes, and soon the prpcess 

 is repeated. By this means the fluid matter is squeezed out and 

 carried into the small intestine, while the more solid portions remain 

 behind for further action by the gastric juice. Little or no digestion 

 of fat takes place in the stomach. 



Stomach digestion of ruminants. — Tho the first three stomachs of 

 ruminants secrete no enzymes, but only water, they are highly 

 important in digestion. The nutrients of plants are enclosed within 

 the cell walls, and where these are of hard, thick cellulose, as in hay 

 and straw, the digestive fluids can not easily reach and attack the 

 nutrients locked within. As we have seen, when ruminants swallow 

 solid food it passes chiefly into the paunch. Here it is softened by the 

 moisture, slowly but thoroly mixed by muscular contractions, and 

 ground against the rough lining. All this prepares the food for easy 

 digestion farther on. 



A considerable amount of actual digestion also occurs in these first 

 stomachs, especially in the paunch, thru the action of bacteria. The 

 bacteria attack the cellulose and pentosans of the feed (for which 

 Nature has provided no other means of digestion) and break them 

 down with the production of heat and the formation of organic acids 

 and of gases, including marsh gas, carbon dioxid, and hydrogen. The 

 acids serve as food, the same as do the sugars, but the gases are useless 

 and are excreted. In this bacterial action the cell walls of the feed 

 are broken down, setting free the nutrients contained within. Not only 

 do the bacteria digest cellulose and pentosans, but they may also attack 

 starch and sugar. This action is detrimental, for these nutrients 

 would be digested more efficiently later on in the small intestine, while 

 in the bacterial digestion a considerable part of their feeding value is 

 lost thru the heat and gases produced in the fermentations. When 

 fresh, easily fermented forage, such as green clover or alfalfa, is eaten, 

 the bacterial action may then be so great that gas is produced faster 

 than it can be carried away, and "bloat" results. 



After rumination, the reswallowed food passes chiefly into the 

 manyplies, or third stomach, where it is further ground between the 

 muscular folds before being forced into the fourth, or true stomach. 

 In the latter the digestive processes are similar to those in the simple 

 stomach, as previously described. 



