Synergistic enhancement of chemical composition, fermentation characteristics, and microbial community dynamics in triticale silage by inoculation with Streptococcus bovis and Lactobacillus plantarum

Abstract

Background Whole-plant triticale is rich in starch, which can be partially degraded into soluble sugars required by lactic acid bacteria (LAB) during ensiling and is an important energy source for ruminant animals. However, few studies have reported the utilization of starch by LAB in triticale silages. This study aimed to investigate the effects of Streptococcus bovis and Lactobacillus plantarum on the chemical composition, fermentation characteristics, bacterial communities, and metabolic pathways of whole-plant triticale silage. Fresh triticale harvested at the milk stage was ensiled in sterile distilled water (CON), Streptococcus bovis (ST), Lactobacillus plantarum (LP), or a combination of S. bovis and L. plantarum (LS) for 3, 7, 15, or 30 days. Results During ensiling, the pH and water-soluble carbohydrate (WSC) content in the inoculant groups were significantly lower than those in the CON group (P < 0.05), especially in the LS group (P < 0.05). After 7 days of ensiling, the ST and LS groups had lower (P < 0.05) starch content and higher (P < 0.05) concentrations of lactic acid (LA) and acetic acid (AA). Inoculation with S. bovis and L. plantarum, either alone or in combination, increased the abundance of LAB such as Lactobacillus and Pediococcus while reducing the abundance of Weissella, Rosenbergiella, Pantoea, Enterobacter, and Klebsiella. Metabolic function prediction analysis indicated that inoculation with S. bovis enhanced starch and sucrose metabolism during the early stages of ensiling. Streptococcus positively correlated with LA (P < 0.05) and AA but negatively correlated with starch content, pH, Propionic acid (PA), and LA/AA (P < 0.05). Conclusions S. bovis inoculation increased starch hydrolysis and carbohydrate metabolism during the early ensiling stages. Both S. bovis and L. plantarum synergistically improved the fermentation characteristics and microbial communities of triticale silage. Therefore, S. bovis can be used as an additive or for fast start-up to improve silage fermentation quality.