576 



NUTRITION OF FARM ANIMALS 



On the other hand, of course, the digestibility of the stalks and 

 leaves alone (stover) diminishes as in the case of other grasses 

 as the plant grows older. 



681. Proportions of vegetative organs. The composition 

 and digestibility of the grasses is also materially affected by the 

 proportions of the various vegetative organs. The influence of 

 the large proportion of seed in the maize plant has already been 

 mentioned. In general, the leaves of the grasses, and of other 

 forage plants as well, are more tender and contain less crude 

 fiber and more proteins than the stems. Leafy species and 

 varieties therefore tend to have a higher feeding value than 

 those which consist more largely of stems, and any influences, 

 such as thickness of planting, manuring, season, and the like, 

 affecting the relative proportion of leaves, tend also to affect 

 the value of the crop. The combined result of all these factors 

 is to make the composition of grass, or of the hay or silage made 

 from it, extremely variable. American analyses of timothy 

 hay, for example, show total protein ranging from 3.8 per cent 

 to 9.8 per cent and fiber varying from 22.2 per cent to 38.5 per 

 cent. The corresponding variations in hay from a few other 

 grasses are as follows : 



TABLE 166. PROTEIN AND FIBER IN VARIOUS GRASSES 



That these variations in composition are accompanied by cor- 

 responding differences in digestibility has already been pointed 

 out. Moreover, the percentage of crude fiber in roughage 

 appears to be a fairly accurate index of the relative expendi- 



1 Entire plant, usually containing considerably more water than hay. 



