Abstract
Pure swards of orchardgrass, Phyllox, Kitamidori, and St. Hokkaido were harvested at the stages of maturity during first growth in the spring, and in the subsequent regrowth. Each batch of harbage was fed to 5 wethers in a digestion trial under the condition of voluntary intake. These 32 fresh orchardgrass samples were used to evaluate the relationships between the voluntary intake (VI) and the chemical composition, digestibility, digestible nutrient. VI was significantly correlated with the contents of crude protein, ADF, ADL, digestibility of crude protein, cell wall (CW), dry matter, gross energy, and the amounts of DCP, TDN and DE. It was generally observed that VI was estimated as the ratio of fecal dry matter excretion to the percent of dry matter undigested. Fecal dry matter excretion (g/day/W^<0.75>) of wethers in their full intake was about 22g, was varying little between the first cutting in spring and aftermath. There was not significant correlation between VI and fecal dry matter excretion. Digestibility of dry matter: VI (r=0.70, p<0.05) and indigestibility of dry matter: indigestible CW content (r=0.93, p<0.01) all have significant correlations. These data are consistent with the theory that indigestible CW inhibit VI and voluntary digestible nutrient intake.
