24 FEEDING STUFFS AND THEIR PREPARATION 



It will be seen from the above that timothy hay, a rough- 

 age, is much higher in crude fiber and lower in nitrogen free 

 extract than is corn, a concentrate. 



In general, the value of a feeding stuff depends upon 

 the digestible nutrients the feed contains. The animal 

 cannot use all of each nutrient in a feed. There will be some 

 waste. It is only the part of the feed that the animal 

 utilizes that is of value. This is called the digestible 

 nutrient and can be determined only by experiment. By 

 digestibility is meant the relation which that portion of the 

 nutrient retained and used by the animal bears to the total 

 amount. This may be expressed in percentages called 

 coefficients of digestibility. There are three general 

 methods employed for determining the digestibility of feed. 

 Oniy one of these, the most common and the least com- 

 plicated, is explained in the following paragraph. 



How Digestibility is Determined. — Digestion experi- 

 ments are conducted with ruminating animals, either cattle 

 or sheep. The animal is confined in a stall and an accurate 

 account kept both of the feed fed and the amount of solid 

 excrement. Both feed and solid excrement are weighed 

 and analyzed. The difference in analysis between these 



