80 HATCH P:XPERIMENT STATION. [Jan. 



The results show that the pentosans comprise from one- 

 tenth to nearly one-third of the entire feed stuff, the grains 

 and by-products naturally containing the smaller and the 

 coarse feeds the larger amounts. 



The pentosans are found to be fully as digestible as the 

 other fodder groups in case of upland hays and most by- 

 products, but rather less digestible in swale hay, salt grasses 

 and wheat bran. An explanation of this is to be found in 

 the fact that association affects the digestibility of the pen- 

 tosans. Late-cut hays, straws and bran contain considerable 

 lignified matter, and it is this lignified or incrusting sub- 

 stance which exerts a negative influence upon the digesti- 

 bility of all of the several fodder groups, the pentosans 

 proving no exception. Most grains contain relatively small 

 amounts of lignin and pentosans. Concentrated by-products, 

 the residues of the several grains from which the starch, fat 

 or both have been removed, contain higher pentosans per- 

 centages than the grains, for the reason that the pentosans 

 are found largely in the external coverings, which are always 

 more or less lignified. The pentosans, being closely asso- 

 ciated with the lignified tissue, are in such cases less digest- 

 ible than the protein, fat or total extract matter. In other 

 cases (gluten feed), the incrusting substances being less de- 

 veloped, the pentosans have a digestibility nearly equal to 

 the other groups. 



Lehmann,^ and later Kellner and Kohler,^ have clearly 

 shown that lignin interferes with the digestibility of the 

 pentosans. The former subjected oat and wheat straws to 

 the action of dilute sodium hydrate, under low pressure, for 

 several hours, neutralizing with hydrochloric acid. After 

 this treatment the pentosans in oat straw showed an in- 

 creased digestibility of 69 per cent, and those in wheat 

 straws of 115. Kellner, by a similar process, found the 

 fibre and pentosans in extracted rye straw to be respectively 

 84.5 and 84.8 per cent, digested. 



The experiments herein reported show that sheep were 

 able to digest from 40 to 90 per cent, of the pentosans in 

 grains and by-products. It has been held, however, that, 



' Landw. Jahrbiicher '24. Jahrg., 1896; I Erganzungsband, p. 118. 

 " Landw. Versuchsstationen 53, p. 278. 



