Effects of Ensiling Density on the Fermentation Profile and Aerobic Stability of Wilted Alfalfa Silage

Abstract

Silage quality and aerobic stability are the key factors affecting the utilization efficiency of silage feed, and ensiling density stands as the fundamental principle of silage making. The experiment presented here evaluates the effects of ensiling density on the silage quality and aerobic stability of alfalfa silage. In this experiment, alfalfa was harvested, wilted, chopped, and subsequently packed into 10 L laboratory silos. The ensiling densities were set to 800 g/L, 700 g/L, and 600 g/L, respectively, with three replicates in each group. Sampling and analysis were carried out at 45 days of silage and 8 days of aerobic exposure. The results showed that ensiling density significantly (p < 0.05) affected the content of ammonia nitrogen, Flieg score, the counts of yeast, and mold. After 45 days of ensiling, 800 g/L silage had the highest contents of dry matter, water-soluble carbohydrates, crude protein, lactic acid, and total organic acids, and the lowest pH and ammonia nitrogen compared to the 700 g/L and 600 g/L silage (p < 0.05). The Flieg score of 800 g/L silage was higher than those of the 700 g/L and 600 g/L silage. The counts of yeast and mold of 800 g/L silage was significantly lower than those of the 700 g/L and 600 g/L silage. During aerobic exposure, a consistent decrease in lactic acid and an increase in pH were observed among all silages. The aerobic stability of 800 g/L silage (156 h) was significantly higher than that in the 700 g/L (136 h) and 600 g/L silage (111 h). It was suggested that the increasing ensiling density above 800 g/L was an effective method to improve both the silage quality and the aerobic stability of alfalfa silage.