LAUSR

BACKGROUND Wilting affects the chemical compositions and epiphytic microorganisms of grasses to some extent, thereby influencing the fermentation characteristics of silage. The present research investigated the effects of wilting in a cloudy day and ensiling temperatures (20 °C, 30 °C and 40 °C) on the fermentation of Napier grass (Pennisetum purpureum). RESULTS Wilting in a cloudy day significantly decreased the water-soluble carbohydrate content (P < 0.05) and significantly increased pH, counts of lactic acid bacteria and aerobic bacteria in grass (P < 0.05). Wilting increased the relative abundance of Enterobacteriaceae family and that of some genera like Acinetobacter, Pantoea and Lactococcus, and decreased that of Sphingomonas and Methylobacterium in fresh grass. Although ensiling increased the relative abundance of Lactobacillus, a Enterobacteriaceae genus was the dominant microorganism in Napier grass before ensiling and after ensiled. Wilting increased pH, acetic acid, butyric acid and NH3 -N contents, and reduced the lactic acid content of Napier grass silage. Additionally, the fermentation quality of silages at 30 °C were poorer, irrespective of wilting, indicated by high pH, high butyric acid and NH3 -N contents, high relative abundance of Clostridium and Bifidobacterium, and low lactic acid content. Ensiling at 40 °C enhanced lactic acid bacteria fermentation, and suppressed clostridial fermentation and the growth of microorganisms in silages. CONCLUSION Napier grass should be immediately ensiled after harvested in a cloudy day and ensiling at 30 °C should be avoided to prevent the poor fermentation. This article is protected by copyright. All rights reserved.