204 ELEMENTS OF AGRICULTURE 



CHAPTER XXXVIIL— Digestibility of Stock 

 . Foods 



198. The Value of a Food Depends on Its Digesti- 

 bility. — Only a part of the food eaten by animals is 

 digested; the undigested portion is passed off as manure. 

 Naturally, the portion digested is of much greater 

 value to the animal body than the undigested portion. 

 So in judging of the value of a cattle food, we must 

 always take into consideration the digestibility of the 

 nutrients contained in the food. Table V of the 

 Appendix shows the results of a number of analyses 

 of different foods, most of which are very different in 

 composition. These foods also differ very much in 

 the amounts of digestible nutrients they contain. Let 

 us see how it is possible to determine the digestibility 

 of the nutrients of cattle foods. 



199. Digestion Experiment.— Of the food eaten by 

 animals, a part is digested and retained in the body, 

 and a part passed off as manure. Now, suppose we 

 feed to an animal a weighed portion of food in which 

 we have determined accurately the amounts of the 

 various nutrients. If no other food has been given the 

 animal, we can collect the manure resulting and in it 

 determine the amounts of the nutrients undigested. 

 The difference between the total nutrients in the food 

 and the undigested nutrients in the manure will give 

 us the digestible nutrients. Suppose we select an ox 

 and feed him 30 pounds of hay per day. The hay con- 



