64 PRINCIPLES OF FEEDING FARM ANIMALS 



eral matter are of little practical value, and hence they are not 

 given often. 



Digestibility of Crude Protein. — Protein from the con- 

 centrates is digested more thoroughly, as a rule, than pro- 

 tein from the roughages. This is probably due to the fact 

 that the protein of the roughages is surrounded by tougher, 

 more fibrous cell walls than the protein of the concentrates. 

 Protein of the nitrogenous concentrates {i.e. concentrates 

 containing a large amount of protein) such as the oil meals, 

 legume seeds, distillers' grains, and gluten feed have the 

 highest coefficients of digestibility, usually between 75 and 

 90 per cent. Proteins of the non-nitrogenous concentrates, 

 as corn, oats, and wheat, are usually from 60 to 80 per cent 

 digestible. Proteins of the concentrates which are relatively 

 high in crude fiber, as corn-and-cob meal and the brans, 

 have the lowest coefficients of digestibility among the con- 

 centrates, running sometimes as low as 50 per cent. 



Of the roughages, the proteins of the leguminous hays, as 

 alfalfa, clover, and cowpeas, have the highest coefficients 

 of digestibihty, — 60 to 75 per cent, being as high or higher 

 than some of the concentrates. The proteins of the straws 

 have the lowest coefficients of digestibihty, — 23 to 33 per 

 cent. 



In general, the digestibility of crude protein seems to 

 increase \\ith the amount of protein in the feed and to 

 decrease with the amount of crude fiber. 



Digestibility of Nitrogen-free Extract. — Generally speak- 

 ing, nitrogen-free extract is the most digestible nutrient, due 

 to the fact tliat the starches and sugars are quite easily 

 and quite thoroughly digested. As a rule, the nitrogen-free 

 extract of the concentrates is more digestible than that of 



