366 ALFALFA FARMING IN AMERICA. 



less like it chemically. The toughness and firmness of forage 

 plants depend largely on this constituent. Cotton and linen are 

 nearly pure cellulose. Obviously the crude fiber is of inferior 

 nutritive value; indeed, there is good reason to believe that in 

 many cases such of it as is digested by animals is utilized at an 

 expenditure of more energy than is yielded by the digested fiber. 



The nitrogen-free extract includes starch and the sugars as 

 well as other less well known carbohydrates. In some tables 

 this group is listed as carbohydrates, without due regard, how- 

 ever, for the fact that the cellulose of the crude fiber is a car- 

 bohydrate. 



The crude fat extracted from hay, or from other materials, 

 obtained by drying the green parts of plants, includes some 

 chlorophyl, the green substances of leaves, and other compounds 

 that are not fats, as well as any fat in the feed. 



The water of a feed possesses no nutritive power and is not 

 different from water taken by drinking. 



Studying now the table showing the percentages of the sev- 

 eral constituents of the water-free hay, it will be seen that there 

 are progressive changes as the plant becomes more mature. It 

 must not be supposed, however, that there is an actual decrease 

 in the total amount of any food principle in the crop, but only 

 that as maturity takes place certain constituents are produced 

 in greater proportion, thus adding to their percentage amount 

 while correspondingly reducing the percentage of the constitu- 

 ents produced at a slower rate. 



The hay produced by cutting when the alfalfa was about ten 

 per cent, in bloom is seen to be richer in ash, protein and fat 

 than that produced by later cuttings, while the crude fiber and 

 the nitrogen-free extract increase in percentage as the plant 

 matures. The especially valuable protein is present to an extent 

 more than one-fourth greater in the hay made at the first stage 

 than it is in that made at the third stage, while the questionable 

 crude fiber is more abundant in the later stages. 



Digestibility of Alfalfa. While it is true that a certain residue 

 of indigestible matter is necessary for animals, and especially 

 for ruminants, which are accustomed to bulky feed, we seldom 

 need to give attention to this in practice, as feeds are ordinarily 

 excessively supplied with such indigestible substances. Quite 

 the reverse, we are justified in prizing more highly those feeds 

 which show a high degree of digestibility. A proper apprecia- 

 tion of alfalfa hay thus requires consideration of its digestibility. 



The digestibility of the hays referred to was ascertained and 

 the following table shows the results. It gives the percentages 



