903 The Feeding of Farm Stock. [feb., 



various ferments (or enzymes) contained in the digestive 

 juices (saliva, gastric juice, pancreatic juice, bile, &c.) with 

 which the alimentary tract of the animal is, under normal 

 conditions, liberally provided. In the latest stages of the 

 passage of the food through the animal further digestive 

 action is effected by living bacteria, whose action, however, is 

 more wasteful than that of the enzymes. 



The general effect of these various processes is to change 

 as large a proportion as possible of the different nutrients 

 into soluble forms, which then pass directly or indirectly into 

 the blood stream, and are made to serve the various require- 

 ments of the animal. 



The matters removed from the food in this way are said 

 to be digested, whilst the residue which resists the digestive 

 forces — the undigested matter — is eventually ejected from the 

 body in the solid excrement or dung. 



It is obvious, therefore, that only the digestible portion of 

 foodstuffs can have any direct feeding value, and hence 

 the value to the animal of a foodstuff is determined primarily 

 not so much by its total content of albuminoids, oil, &c, 

 as by the proportion of these present in digestible form (see 

 Leaflet No. 74, p. 5). Although the indigestible matter 

 cannot supply nutriment to the animal, it may influence the 

 efficiency of digestion in other ways, i.e., by exerting a bene- 

 ficial stimulus upon the walls of the digestive organs or by 

 swelling the bulk of the food up to a proportion that is best 

 suited to the capacity of the stomach and bowels. 



Similarly also certain pleasant-smelling or sharp-tasting 

 substances that are present in small quantities in many food- 

 stuffs (e.g., hay, roots, malt coombs, treacle), although they 

 have no direct nutritive value, add so greatly to the aroma 

 and palatability of these foods that they are commonly 

 accredited with an appreciable beneficial influence upon the 

 utilisation of the food by the animal — especially in the case 

 of milk-production. 



These indirect effects of indigestible matter and of "stimu- 

 lants " are, however, so vague and incapable of measurement 

 that it is safest to regard them as insignificant in comparison 

 with the direct value of the digested nutrients. 



The table on page 901 gives an indication of the proportions < 



