PERENNIAL FORAGE GRASSES 15 



12. Digestibility. Comparatively few digestion experiments 

 have been made with the hay of the perennial forage grasses, 

 but it is generally conceded that the coefficient of digestion 

 for one species of grass will apply fairly to another if both 

 are harvested at proper stages of maturity and cured in a 

 similar manner. In a general way, 75 to 90 per cent, of the 

 dry matter of grains and other concentrates is digested by 

 ruminants, 50 to 65 per cent, of the hay of grasses and legumes, 

 and 40 to 50 per cent, of the straw of cereals. 



The net nutritive value of hay is much less than that of 

 grains, not only because it contains less percentage of digestible 

 nutrients, but also because a larger proportion of the energy 

 is used in masticating and digesting the hay. The energy 

 being thus used is not available for the production of work, 

 flesh, or milk. The energy of mastication and digestion mani- 

 fests itself in heat, however, and helps to keep the animal 

 warm. Hay and straw may, therefore, be used in wintering 

 mature animals when they would not be useful when used alone 

 for work or for growing animals or for the production of milk. 

 As illustrating the differences in net nutritive value of different 

 foods when fed to horses, the trials by Zuntz and Hagermann, 

 of Germany, are given on the next page. 1 



II. SEEDS AND MIXTURES 



13. Quality of Seed. No factor, perhaps, has a greater influ- 

 ence on the economic use of forage plants, whether grasses or 

 legumes, than the quantity and the quality of the seed produced. 

 Apart from its hereditary power, the quality of seed is de- 

 termined by the purity, the germinating power, the size of the 

 seed, and the weight per bushel. The higher the purity, 

 germination and weight per bushel, and the larger the grain, 

 the more valuable the seed. In some instances as, for ex- 



1 Landw. Jahrb., 27 (1898), No. 3, pp. 440. 



