MAKTJAL OF CATTLE-FEEDING. 65 



wliicli comes from tlie stomach is converted into a more or 

 IcbS thin, milky fluid, called chjle. 



The ease of dig^estion depends on yarions circum- 

 stances. 



Digestion is both a chemical and physical process, con- 

 sisting of solution and chemical change of the nutrients by 

 means of the digestive fluids, and the rapidity of this pro- 

 cess depends, in general, upon the same conditions which 

 determine that of similar processes outside the body. Ilai d 

 and compact fodder is less easily digested than that which 

 is soft and watery, other things being equal, simply be- 

 cause it is not so easily penetrated by the juices, and hence 

 exposes less surface to their action, just as coarse salt dis- 

 solves more slowly than fine. 



If the nutrients are shut up in insoluble envelopes, they 

 are protected from the action of the juices. Thus, if we 

 have starch in a cell whose walls are incrusted thickly with 

 the indigestible (because insoluble) lignin, the starch may 

 be, to a large extent, protected and escape digestion. So, 

 too, if whole grain is fed and escapes mastication, the 

 hard outer coats of the seed protect the interior, and the 

 grain is frequently found with little alteration in the ex- 

 crements. 



In a chemical process, the proportions of the substances 

 concerned are of the greatest importance. 



So, too, in digestion, the proportions of albuminoids, 

 carbhydrates, and fat, exercise an important influence on 

 the digestibility of each of these groups, though exactly in 

 what way we are ignorant. 



That a moderate proportion of fat aids the digestion of 

 the albuminoids in the stomach, has already been men- 

 tioned. Too great an amount of fat, on the contrary, 

 hinders digestion. 



