Effects of lactic acid bacteria inoculants and fibrolytic enzymes on the fermentation quality, in vitro degradability, ruminal variables and microbial communities of high‐moisture alfalfa silage

Abstract

AbstractThe silage additives not only influence the fermentation quality of silages, but may have positive effects on animal performance by affecting the ruminal fermentation. This study was conducted to determine the effect of lactic acid bacteria (LAB) inoculants, either alone or in combination with fibrolytic enzymes on the fermentation quality, and ruminal nutrients degradability, fermentation profile and microbial communities of high‐moisture alfalfa silage. Alfalfa (206 g dry matter [DM]/kg fresh matter) was ensiled in laboratory‐scale silos with four experimental variants: (a) deionized water (Control); (b) LAB inoculants (Lactobacillus plantarum and Pediococcus pentosaceus combination; I); (c) fibrolytic enzymes (cellulase and hemicellulase enzymes combination; E); (d) a mixture of I and E (IE). All silos were opened after 45 days for determining the silage quality. Further, the four experimental silages were used to measure in vitro rumen degradability, fermentation profile and bacterial populations by fermenting with buffered rumen fluid. The addition of I stimulated a more efficient homofermentation of high‐moisture alfalfa silage than in the variants without I, as evidenced by higher lactic‐to‐acetic acid ratios and lower DM losses, and IE addition further enhanced the homofermentation. Compared to the Control, the addition of E increased the proteolysis, and decreased in vitro degradability of DM (IVDMD) and crude protein of DM (IVCPD) as well as in vitro gas production of 48 hr (GP48). The addition of I reduced the proteolysis and methane production, and increased the IVDMD, IVCPD, GP48, ruminal short‐chain fatty acids concentrations and microbial protein production. The populations of Genus Prevotella were higher in silages produced with I, but lower with E than the Control. The data suggested that the addition of LAB inoculants alone or together with fibrolytic enzymes could improve the fermentation quality and nutritive value of high‐moisture alfalfa silage.