THE DIGESTIBILITY OF FEEDINGSTUFFS 65 



the roughages. The cHgestibihty of the nitrogen-free ex- 

 tract of the cereals and their by-products is especially high, 

 — usually from 80 to 93 per cent, due to the large amount of 

 starch which they contain. 



The nitrogen-free extract of the roughages is less digestible, 

 owing to the smaller amount of starch and larger quantity 

 of less digestible carbohydrates, such as pentosans, which it 

 contains. The coefficients of digestibility of the nitrogen- 

 free extract of the roughages are usually from 40 to 70 per 

 cent. 



In general, the digestibility of nitrogen-free extract in- 

 creases with the amount of starch which it contains, and 

 decreases with the amount of crude fiber in the feed. 



Digestibility of Crude Fiber. — The determination of the 

 digestibihty of crude fiber, owing to errors in the method of 

 analysis, is only approximate at best. In many digestion 

 experiments the digestibility of the nitrogen-free extract 

 and crude fiber are not determined separately but are deter- 

 mined together as '^ carbohydrates." 



Unhke the other nutrients, the crude fiber of the roughages 

 is usually more digestible than the crude fiber of the con- 

 centrates. Thus the coefficients of digestibility of the con- 

 centrates are usually between 30 and 60 per cent, while 

 those of the roughages are between 45 and 65 per cent. The 

 crude fiber of corn fodder and the hays is usually more 

 digestible than the crude fiber from the straws. This is 

 due probably to the latter containing a larger amount of 

 coarse, woody material. Also, the crude fiber of early cut 

 hay is more digestible than that of late cut hay. Thus the 

 crude fiber of timothy hay cut when in bloom had a coefficient 

 of digestibility of 57 per cent while timothy hay cut after 



