Impact of Adding Saccharomyces Cerevisiae and Lactobacillus Buchneri on Fermentation, Aerobic Stability, Nutritive Value and Microbial Communities in Corn Silage

The objective of this study was to assess the impact of additives of Lactobacillus buchneri in combination with Saccharomyces cerevisiae on the fermentation characteristics, aerobic stability, nutritive value and microbial communities of ensiled corn silage. Whole crop corn (391 g kg^-1 DM) was either uninoculated (Control) or inoculated with S. cerevisiae and L. buchneri at the following concentrations: S. cerevisiae 10⁴ CFU g^-1 fresh forage (Y4), S. cerevisiae 10⁵ CFU g^-1 (Y5), S. cerevisiae 10⁴ CFU g^-1 + L. buchneri 10⁵ CFU g^-1 (Y4L5) and S. cerevisiae 10⁵ CFU g^-1 + L. buchneri 10⁴ CFU g^-1 (Y5L4), and ensiled in mini silos for 118 d, followed by 7 d of aerobic exposure. Changes in fermentation characteristics and nutritive value were assessed in terminal silages. Quantitative PCR (qPCR) was used to quantify the inoculants S. cerevisiae and L. buchneri, and total yeast, fungal and bacterial communities in silage. The composition of bacterial and fungal communities during ensiling and aerobic exposure was characterized using 16S rDNA and ITS sequencing, respectively. The concentration of lactic acid rapidly increased (P < 0.05) in all treatment silages during the first 7 d, with pH declining to 4.0 and remaining at a similar level until the end of ensiling. Although Y4L5 contained a higher (P < 0.05) concentration of acetic acid compared to Control, fermentation characteristics of silage were similar among all the treatments after 118 d ensiling. Inoculation with S. cerevisiae had no detrimental effect on the aerobic stability of silage, while addition of L. buchneri did not prevent the silage spoilage with pH across all treatments increasing to an average of 8.0 after 7 d of aerobic exposure. Total yeast, bacterial and fungal communities as quantified by qPCR were not altered by the inoculants after ensiling or aerobic exposure process. Sequencing results showed temporal shifts of bacterial and fungal populations during ensiling and aerobic exposure stage. Concentrations of S. cerevisiae and L. buchneri in all inoculated treatments remained higher (P < 0.05) than Control after ensiling, with numbers of S. cerevisiae increasing after 7 d of aerobic exposure. However, inoculation of S. cerevisiae and L. buchneri did not alter the overall composition of bacterial and fungal communities in silage, as indicated by principal coordinate analysis. Our findings suggest that abundance of the beneficial yeast inoculants can increase or remain the same in silage during aerobic exposure stage prior to feeding to animals.