Effects of re-ensiling on the fermentation quality and microbial community of napier grass (Pennisetum purpureum) silage

BACKGROUND With the rapid development of animal husbandry, the silage trade has increased in frequency. The re-ensiling of materials is often required before or after trading, resulting in the exposure of the silage to air before re-sealing. To develop a re-ensiling technique for silage, different silage exposure periods were simulated to check the possible effects on the fermentation quality and microbial community of silage. RESULTS Fresh and wilted napier grass (Pennisetum purpureum) were ensiled for 90 days, then exposed to air for 0, 6, 12, 24, 36 or 48 h, before being re-ensiled. As a control, grass was directly ensiled for 180 days. Wilting increased the relative abundance of Klebsiella. The relative abundance of Paenibacillus in the unwilted silage was much higher than that in the wilted silage. Re-ensiling increased the relative abundance of Lactobacillus, but decreased the relative abundances of Klebsiella, Bacillus, and Paenibacillus. In addition, Lactobacillus became the dominant bacteria in the re-ensiled fresh and wilted silages. Re-ensiling within 48 h of exposure did not affect the fermentation quality of the wilted silage, whereas that of the unwilted silage declined when exposed to air for over 24 h. CONCLUSION Re-ensiling wilted napier grass silage within 48 h of aerobic exposure did not cause the fermentation quality to decline. The unwilted napier grass silage contained a higher relative abundance of Paenibacillus and significantly deteriorated when re-ensiled after over 24 h of aerobic exposure. (c) 2021 Society of Chemical Industry