Abstract:
The aim of this study was to compare two tropical grass species, Panicum maximum and Digitaria eriantha, in terms of silage fermentation attributes and certain rumen fermentation characteristics of silage made either at the boot or full bloom stages of growth. A lower silage pH was recorded for the D. eriantha than for the P. maximum silage. Neither species nor maturity stage had a significant effect on silage ammonia nitrogen, or lactic, acetic and butyric acid concentrations. For P. maximum silage total N was higher at full bloom than at the boot stage. D. eriantha had a higher total nitrogen content than P. maximum silage at the boot stage. Rumen pH was lower in sheep fed D. eriantha than P. maximum silage. In P. maximum fed sheep, a higher rumen NH3-N concentration was recorded when silage from the full bloom stage was fed compared to silage from the boot stage. In sheep fed D. eriantha silage, higher concentrations of acetic, propionic, butyric and total volatile fatty acids in the rumen were recorded from full bloom than from the boot stage. Neither species nor stage of maturity had significantly influenced the acetic : propionic acid ratio. The results suggested no significant difference between the species, but the full bloom stage showed a higher nutritive value and better preservation compared to the boot stage silage in both D. eriantha and P. maximum silage.
