Effect of a low temperature tolerant lactic acid bacteria inoculant on the fermentation quality and bacterial community of oat round bale silage

The objective of this study was to investigate the effect of a low temperature tolerant lactic acid bacteria (LAB) inoculant on the fermentation characteristics and bacterial community of oat silage. Oats were harvested at the flowering stage and wilted to dry matter content of approximately 270 g/kg fresh weight. Wilted and chopped oats were used to make mini round bale silages. Silages were prepared without (control) or with a low temperature tolerant LAB inoculant including Lactobacillus plantarum BP18, Pediococcus pentosaceus HS1 and L. buchneri LP22 and then separately stored at different geographic locations (L, Chengdu Plain; H, Qinghai Tibetan Plateau) for 120 days. High contents of water soluble carbohydrate (WSC), crude protein (CP), neutral detergent fiber (aNDF) and acid detergent fiber (ADF) were found in LAB inoculated silage. Inoculation with LAB increased (P < 0.05) lactic acid and acetic acid contents, and decreased (P < 0.05) the final pH of silage stored at the H location. However, LAB inoculation reduced (P < 0.05) the bacterial operational taxonomic units (OTUs), richness index (Chao 1) and diversity index (Shannon) of silage stored at the L location. The dominant genera from silage samples were Lactobacillus, Leuconostoc and Clostridium, with a total relative abundance of 71 similar to 93 %. LAB inoculation increased the abundance of desirable Lactobacillus and inhibited the growth of undesirable Clostridium in silage. Therefore, inoculation of low temperature tolerant LAB at ensiling could stimulate favorable fermentation and reconstruct the bacterial community for better preservation of high moist oat silage nutrients.