A note on the fermentation characteristics and rumen degradation of low moisture alfalfa silage treated with sodium hydroxide or ammonia

The effects of alkali treatment on the fermentation characteristics and rumen degradation of low moisture alfalfa silage were investigated. First crop alfalfa was wilted and ensiled, either directly or after being sprayed with NaOH or NH₃ solution (1.72% dry matter (DM)). The herbages were stored in laboratory silos and opened at 1, 2, 7, 14, 28 and 56 days after storage. Each NaOH and HN₃ addition increased the pH value and delayed lactic acid production of the silage. Both alkali treatments decreased proteolysis during ensilage, and NaOH-treated silage showed the highest protein (hot water insoluble nitrogen) content. Nitrogen solubility in a mineral buffer solution was decreased by the alkali treatments, and NaOH-treated silage showed the lowest solubility. Degradation characteristics of DM and N in the rumen were determined by nylon bag incubation of 56th day silage samples with two rumen fistulated goats. The NaOH treatment significantly decreased the soluble N fraction (63.7%, 54.7% and 60.6% for untreated, NaOH-treated and NH₃-treated silage, respectively) but did not influence the extent of degradation. The treatment tended to decrease the rate of N degradation. In contrast, the NH₃ treatment significantly increased the rate of DM degradation (0.158 h^-1, 0.151 h^-1 and 0.182 h^-1 for untreated, NaOH-treated and NH₃-treated silage, respectively) without any great changes in the proportions of soluble and degradable fraction.