The effects of Lactobacillus plantarum with feruloyl esterase-producing ability or high antioxidant activity on the fermentation, chemical composition, and antioxidant status of alfalfa silage

Abstract

This study was aimed to evaluate the effects of an efficient ferulic acid esterase-producing Lactobacillus plantarum A1 and an antioxidant strain L. plantarum 24-7 on fermentation, chemical composition, antioxidase activity and antioxidant status of alfalfa silage. Freshly chopped and wilted alfalfa with about 30 % dry matter (DM) was treated either without (CON) or with L. plantarum A1 (Lp A1), L. plantarum 24-7 (Lp 24-7), and a reference strain of L. plantarum MTD/1 (Lp MTD/1) at an application rate of 1 × 106 CFU/g fresh weight, respectively, and ensiled for 7, 14, 30, 60, and 90 d. All inoculants improved silage quality as indicated by low pH, high lactic acid concentration, and lactic acid/acetic acid compared to the CON from 7 d to 90 d of ensiling. After 90 d of ensiling, the lowest DM loss and non-protein N were observed in the Lp A1 inoculated silage. Inoculation of Lp A1 also decreased the neutral detergent fiber, acid detergent fiber, and acid detergent lignin concentrations in the later period of ensiled alfalfa, and increased ferulic acid concentration during all ensiling duration. The highest ferulic acid concentration was detected in Lp A1 treated silage after 30 d (P < 0.05). In addition, the total antioxidant capacity and glutathione peroxidase activity in the Lp A1 and Lp 24-7 inoculated silages were higher than that in the CON and Lp MTD/1 silages from 30 d to 90 d of ensiling. However, lower lipoxygenase activity was found in Lp A1 and Lp 24-7 inoculated silages during the whole fermentation process. Both Lp A1 and Lp 24-7 improved the total fatty acid concentration and the proportion of polyunsaturated fatty acids in total fatty acid of ensiled alfalfa when compared with the CON and Lp MTD/1 silages after 90 d of fermentation (P < 0.05). Therefore, inoculation of ferulic acid esterase-producing Lp A1 or antioxidant strain Lp 24-7 not only improved the fermentation quality and chemical composition of ensiled alfalfa but also enhanced the antioxidant status of the silage.