Effect of Ensiling Density on Fermentation Characteristics and Aerobic Stability of Pennisetum giganteum Silages

The current work aimed to evaluate the effect of ensiling density on the fermentation quality and aerobic stability of Pennisetum giganteum silages. The silage was ensiled in laboratory silos (1 L), and three treatments were designed according to different ensiling densities: (1) low density (LD, 750 kg/m3); (2) medium density (MD, 900 kg/m3); and (3) high density (HD, 1050 kg/m3). During ensiling, the silage was sampled for a fermentation quality analysis. All silages were well preserved, as indicated by the high lactic acid (LA) content and low pH (<4.2). The MD treatment had the highest acetic acid content (24.9 g/kg dry matter) and the HD treatment had the lowest ammonia nitrogen (NH3-N) content (68.2 g/kg total nitrogen, TN) among all silages after 45 days of ensiling. The aerobic stability of HD, MD, and LD persisted for 51 h, 54 h, and 48 h, respectively. The NH3-N contents of HD and MD were below 80 g/kg TN during aerobic exposure. These results show that the increase in ensiling density improved the fermentation quality and aerobic stability of Pennisetum giganteum silages.