32G BOARD OF AORICULTURE. 



the opportunity has been improved for comparing the results obtained 

 for protein by artificial digestion witli those reached by the use of 

 animals, and also of testing one or two gcneralh' accepted conclu- 

 sions in the light of recently acquired knowledge. For the results 

 of tiiis c()in|)arison see ''Laboratory and Experimental Methods." 



The foods with which digestion experiments have been made are 

 Timothy ha}', clover hay, oat straw and })otutoes. The animals 

 used were two full grown wether sheep, which were confined during 

 the time of each experiment in stalls that allowed perfect freedom of 

 motion so far as lying down and moving forward and backward, but 

 which were so narrow that the sheep could not turn around. The 

 finely cho[)[)ed food was fed in such a manner as to insure against 

 loss, and the solid excrement was collected in the usual way by at- 

 taching a rubber bag to the animal by means of a light hai'uess. 



For the sake of convenience and completeness, the following ex- 

 planations are offered for the second time : 



The miiin facts of digestion, and those upon which the methods of di- 

 gest ion experiments are based, are the following: A portion of tlie food 

 whicii an animal eats is dissolved by the several digestive tUiids with which 

 it comes in contact, viz., the saliva, gastric juice, pancreatic juice, etc. 

 That which is dissolved, or digested, is absorbed by certain vessels 

 which are distributed over the lining of the stomach and intestines, passes 

 into the blood, and is then used to maintain and build up the animal body. 

 The undissolved or undigested portion of the food is carried along the 

 alimentary canal, passes from the body as the solid excrement or dung, 

 and constitutes that part of the food wliich is useless for the purposes of 

 nutrition. The method of ascertninintr the digestibility of any cattle food 

 is simple in principle. An animal is fed a weighed quantity of food, of 

 which the composition is determined by analysis. The solid excrement is 

 collected, weiglied and analyzed, and the amount digested is the difference 

 between that which is fed and that which is excreted. From the data 

 thus obtained is calculated the percentage that is diii^ested of eacli ini^re- 

 dient, these several percentages being called the coefficients of dUjestibiHty. 

 As the process of digestion is slow, it is necessary to feed the animal on 

 the weighed ration several days before collecting any excrement, in order 

 that the contents of the intestines may become wholly freed from the res- 

 idue of the previous food, so that the dung collected shall come wholly 

 from the food tested. On account of the irregularity with whicli dung is 

 voided, it is collected for several days, and from the total amount the av- 

 erage for one day is calculated. 



Digestibility of Timothy Hay. 

 This hay was from grass that grew on the College farm and that 

 had stood about two weeks after the period of full bloom. It was 



