162 PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



Vegetable foods differ from foods of animal origin in the respect 

 that the nutritive principles are not present in as concentrated form as 

 in animal foods, and the non-nitrogenous food-stuffs are present in much 

 greater abundance than the nitrogenous ; moreover, vegetable foods are, 

 as a rule, very much less readily digestible than animal foods, from the 

 fact that the nutritive principles are inclosed within cellulose capsules, 

 which offer great resistance to the solvent action of the digestive juices, 

 and which necessitates fine comminution before being capable of being 

 digested and absorbed. As a consequence of this the residue from the 

 digestion of vegetable matter is always very much more abundant than 

 from an animal diet, and hence the intestinal excreta of the herbivora 

 are alwaj r s much more bulky than of the carnivora, or even of the om- 

 nivora. Another point of contrast between vegetable and animal food 

 is found in the difference of inorganic constituents of the ash. Vege- 

 table foods are especially rich in potassium and magnesium salts, and 

 comparatively poor in sodium salts, while chlorides are present in 

 extremely small amount, and phosphates in considerable quantities. 

 As already indicated, in vegetable tissues representatives of all 

 the different food-stuffs are to be found ; thus, vegetable albumen is 

 present, and in its characteristics appears identical almost with the 

 albumen of animal origin. So, also, are carbo-hydrates, oils, and inor- 

 ganic salts. The relative proportions of these substances vary in differ- 

 ,ent plants. The usefulness, therefore, of different forms of vegetable 

 food for different nutritive purposes depends upon differences in the rela- 

 tive proportions of these constituents. The vegetable foods may be 

 given to our domestic animals in the fresh state, containing their natural 

 juices, when they are termed green fodder, or after having been dried 

 by.the sun, when they are called dry fodder. 



Green fodder always contains a large amount of water in proportion 

 to the solids present, the proportion often being 75 per cent, water to 25 

 per cent, solids. Of the solids the albuminous bodies may amount to 10 

 or 20 per cent., the non-nitrogenous extractive matters varying between 

 50 and 60 per cent., while cellulose is present in large amount. All edible 

 grasses and vegetable tops may serve as green fodder. 



Dry fodder consists of the stems and leaves of various grasses and 

 plants after the major part of their water has been removed by evapora- 

 tion by the sun's heat. The proportion of water to solids in dry 

 fodder is reduced to 15 per cent, of the former to 85 per. cent, of the 

 latter. Of the solids of dry fodder cellulose constitutes from 20 to 40 

 per cent., a moderate amount of albuminoids and carbo hydrates, less 

 fat, and a maximum of inorganic matter. 



Green fodder, as a rule, is more readily digestible than dry fodder. 

 Thus, experiments made by feeding oxen at one time with fresh red clover, 



