CHAPTER XXXII 

 NUTRITION OF THE ANIMAL BODY 



322. Nutrition of the Animal Body. The nutrition 

 of the body of the farm animals is through the same 

 processes which have heen previously described for 

 the human body in the study of physiology. The feeds 

 are taken in by the tongue and lips, masticated by the 

 teeth, and digested in the stomach and intestinal canal. 



323. Nutritive Substances. Animals require the same 

 classes of nutritive substances to provide for growth, 

 repair and waste as in the human body. The sub- 

 stances which are taken into the digestive tract are 

 not available for the nourishment of the body until they 

 have been rendered soluble, absorbed and become a part 

 of the blood. The various cells of the body absorb the 

 sugars, proteids, and salts directly from the blood. These 

 substances are absorbed through the cell -walls, just 

 as the yeast absorbs the sugar and albumen from the 

 solution used in our early experiments. (^ 9a.) 



324. Digestive Tract of Domestic Animals. There 

 are important differences in the digestive tracts of the 

 several classes of domestic animals, such that each 

 is adapted to the different classes of substances upon 

 which they feed and thrive. 



325. Digestion by Fowls. Birds swallow their food 

 whole without chewing. It passes first into the crop, 

 where it is stored and softened by soaking. (Fig. 159 I.) 

 Then it passes into the thick-walled, muscular stomach 

 or gizzard. The gizzard is supplied with powerful 



(235) 



