254 STATE BOARD OF AGRICULTURE. 



Digestibility. — While the stomach and intestines of the dairy cow are 

 especially adapted to the digestion of coarse feed, a share of the valuable 

 parts passes through her without digestion. All of the materials we have 

 described, the protein, the carbohydrates and fat, are more or less 

 encased in toughened cells in such a way as to prevent the ready access 

 of the fluids of the stomach and bowels. Were it not for the very 

 large stomach of the cow in which her food soaks in liquids which soften 

 it for the second grinding it receives when she chews her cud, and for 

 the great length of her intestinal canal varying from twelve to twenty 

 times the length of her body, nearly all of the coarser parts of the forage 

 crops must escape digestion. As it is, with this complicated and effective 

 apparatus, which nature has provided, but little more than half of some 

 of the valuable nutrients of the forage crops are absorbed into the cir- 

 culation of the cow and became really useful to her. 



To determine what share of the food consumed is really digested by the 

 cow, extensive experiments have been performed both in the Old World 

 and in this country. 



The first step in one of these digestion experiments is by chemical an- 

 alysis to find out how much protein, carbohydrates and fat one hundred 

 pounds of the food stuff in question contains. Two animals are then 

 weighed daily for a week and fed a weighed daily ration of the material 

 to be tested. At the end of that time the real experiment begins. The 

 animals are weighed daily for the next period, usually of six or seven days, 

 and both the amount of food they consume and the amount of excrement 

 they void are carefully weighed and analyzed. From the data thus ob- 

 tained, the amount of protein, carbohydrates and fat digested is found 

 by subtracting the amounts of each in'the dung from the amounts of each 

 in the feed which the animals consume, in the given time. For instance 

 suppose it was desired to determine what share of the nutrients, protein, 

 carbohydrates and fat, cattle were able to extract from clover hay and 

 utilize in their bodies. Two steers would be fed clover hay for a week, 

 the ration being so regulated that there would be neither gain nor loss 

 in weight. Let us next suppose that the following period of the experi- 

 ment was six days, and that in that time each steer consumed twenty 

 pounds per day of clover hay. The clover hay would contain as shown* 

 by chemical analysis per hundred pounds 



Water - - - - - - - 15.3 pounds. 



Ash -------- 6.2 pounds 



Protein - - - - - - - 12.3 pounds. 



Crude fiber ------- 24.8 pounds. 



Nitrogen-free extract - - - - - 38. 1 pounds. 



Fat -------- 3.3 pounds. 



100.00 pounds. 



In the six days, each steer would consume 120 pounds of clover hay> 

 containing according to this analysis 14.76 pounds of protein. For, if 

 one hundred pounds of hay contained 12.3 pounds of protein, one pound 

 of hay would contain .123 pounds which, multiplied by 120 gives 14.76, 

 as the total amount of protein in the 120 pounds of clover hay consumed 

 in the six days. By using the table of analysis in this way we find that 

 in the 120 pounds of clover hay there would be, besides the 14.76 pounds 

 of protein, 29.76 pounds of crude fiber, 45.72 pounds of soluble carbo- 



