DIGESTION 



401 



If a concentrated feeding-stuff is to be tested, the digestibility 

 of hay is first determined, then the concentrate added, and the 

 digestibility of the mixture ascertained. The nutrients digested 

 from the hay are subtracted from those digested from the mix- 

 ture, and the difference is assumed to represent the material 

 digested from the concentrate. It is assumed that ingredients of 

 the mixture are digested to the same extent as the feeds would 

 be separately, but this is not always the case, as we shall see. To 

 guard against abnormal conditions of the digestive organs, and 

 also to secure a more accurate average, at least two animals 

 should be used. 



The following is an example of an experiment 1 on one sheep. 

 The preliminary feeding was eight days, and the digestion period, 

 ten days. Three sheep were used, but the figures are given for 

 for only one. 



DIGESTION EXPERIMENT WITH ONE SHEEP. 



Artificial Digestion. By artificial digestion we mean labora- 

 tory tests to ascertain the digestibility of constituents of feeding- 

 stuffs. Only with proteids has any measure of success been at- 

 tained in this way. As before stated, the proteids not digested 

 by Kuhn's method are not digested in the animal. Kuhn's 

 method, then, offers us a means for ascertaining the maximum 

 digestibility of the protein of feeding-stuff. The animal cannot 

 digest any more proteids than is indicated by the method, though 

 1 Bulletin 147, Texas Exp. Sta. 



