PSVIII-24 Bacterial and fungal communities during ensiling and aerobic exposure of whole corn silage treated with a bacterial inoculant or a propionic acid-based additive.

Abstract This study investigated the effect of silage additives on a) silage composition and fermentation characteristics, and b) bacterial and fungal communities during ensiling and aerobic exposure. Whole plant corn was harvested at 33% DM and ensiled in vacuum-sealed laboratory silos following treatment with a) deionized water (control; CON), b) a bacterial inoculant, LB+ Supersile® (Strong Microbials Inc., Milwaukee WI; INOC), applied to supply 1 x 105 cfu/g of fresh forage, c) a propionic acid-based additive, Silage SAVOR® Plus (KEMIN Industries, Des Moines, Iowa; PRE), applied at 0.1% of fresh forage, and d) additive plus inoculant (PRE+INOC) applied at the same rates as INOC and PRE. Silage was sampled twice; at silo opening after 180 d of ensiling and 21 d after silo opening. Silage composition and fermentation characteristics were measured at silo opening. For bacterial and fungal communities, we considered the effect of silage additives on two sampling dates in a 4 x 2 factorial arrangement. Bacterial and fungal communities were characterized using 16S rRNA gene amplicon and ITS sequencing, respectively. Treatment of silage with PRE and PRE+INOC increased CP, WSC, and lignin concentration relative to INOC. Main differences in fermentation characteristics among treatments were a greater pH, greater ammonia-N concentration, and lower total acids concentration in PRE and PRE+INOC-treated silages. Firmicutes and Proteobacteria were predominant bacterial phyla during ensiling and aerobic exposure. Firmicutes abundance was not impacted by silage additives but Proteobacteria abundance was reduced (P = 0.057) by PRE and PRE+INOC treatment.