Heat-resistant lactic acid bacteria inoculants modulated the bacterial microbiota and fermentation quality of whole plant maize silage after long-term storage in the subtropical area

Abstract

In tropical or subtropical areas, high temperatures and prolonged storage time usually result in poor fermentation quality, poor aerobic stability and dry matter loss of silages. This study explored the effect of heat-resistant Lactobacillus buchneri TSy1–3 (LB), Lactobacillus rhamnosus BDy3–10 (LR), and their combination (M) on the nutritional characteristics, fermentation parameters and microbiota of whole plant maize silage during long-duration ensiling in the subtropical area. The results showed that long-term ensiling naturally led to a decrease in water-soluble carbohydrate, neutral detergent fiber and acid detergent fiber concentrations. In contrast to the control treatment, LB, LR and M reduced the coliform bacteria population and the nutrient loss, while increased lactic acid bacteria population and acetic acid and propionic acid concentrations after 180 d of fermentation. Moreover, they helped to increase Lactobacillus abundance and made it still dominate the bacterial community during long-term storage. The negative/positive ratio was higher in the LR and LB treatments when compared with the control treatment, suggesting that LR and LB increased the stability of the bacterial community networks. The heat-resistant inoculants rapidly produced lactic acid to modulate the bacterial community composition during 60 d of ensiling, while generated more acetic acid and propionic acid to alter the microflora during 180 d of ensiling. This may be caused by predicted functions indicating that metabolism pathways were modulated by different inoculations and storage times. Overall, heat-resistant lactic acid bacteria improved the nutritional and fermentation quality of ensiled forage and regulated the bacterial community during long-term storage in the subtropical region.