Dry Matter Level Effects on Alfalfa Silage Quality I. Nitrogen Transformations

The effect of initial dry matter (DM) level on the nitrogen tranformations occurring in alfalfa silage was studied. Four dry matter (DM) levels (from unwilted to 64% DM) during three harvests (early June, mid-July and late August) were harvested using a mower-conditioner and forage chopper and ensiled in mini-silos. Silages were analyzed after 0, 1, 2, 3, 4, 5, 7, 10, 14 and 60 days for pH, moisture, and various nitrogen forms. With the exception of some of the unwilted silages, the final concentrations of non-protein nitrogen, free amino acids and ammonia decreased with increasing dry matter within a harvest. Initial proteolysis rate decreased linearly with increasing DM level. However, the proteolysis rate decreased exponentially with time at a rate independent of DM level (0.0456 h-i). Ammonia formation was reduced by increasing DM level although differences among harvests affected ammonia levels as well.