New Yokk Agkicultural Experiment Station. 61 



only partially dissolved in the digestive juices. It follows, then, 

 other things being equal, that the larger the proportion of starch 

 and sugar in the nitrogen-free extract of a feeding stuff the more 

 completely is it digested. 



It also follows that when any manufacturing or other process 

 reduces the proportion of sugars and starch in any gi'ain or other 

 material, the digestibility, and consequently the nutritive value 

 of its non-nitrogenous part, is diminished. We have good rea- 

 son for believing too, that the net value of that which is digested 

 is less than would be the case if the proportion of stai-ch and 

 sugar had not been reduced. 



While the digestion products of fiber and gums are undoubtedly 

 oxidised quite fully and perhaps furnish to tho animal their full 

 calorimetric value (except a small proportion of expiratory methan 

 supposed to come from the fiber) the elaborate researches of Zuntz 

 leave little doubt that their net value is less than digested sugars 

 and starch. This is because the work of mastication and digestion 

 of the former is greater. 



As a matter of illustration we may refer to the great superiority 

 of com meal over timothy hay in point of digestibility, the ex- 

 planation of which is in accordance with the facts just stated. 

 The nitrogen-free extract of maize is mostly starch, the accom- 

 panying fiber being insignificant in amomit whereas in timothy 

 hay there is found a small proportion of sugars and starch, while 

 gums, fiber and other less digestible compounds are abundant. 



Moreover, because of the more resistant qualities of the hay to 

 mastication and propulsion along the alimentary canal, it costs 

 more to digest it than is the case mth maize and other grains. 

 Practice recognizes these facts in its estimate of the grains as 

 against the fodders. 



