Bioaugmentation of sweet sorghum ensiling with rumen fluid: Fermentation characteristics, chemical composition, microbial community, and enzymatic digestibility of silages

Abstract Bioaugmentation of sweet sorghum ensiling with rumen fluid was investigated on the improvement of ensiling performance, microbial community and biodegradability of silages in response to ensiling time and rumen fluid dosage. Bioaugmented silages resulted in the increase of lactic acid/acetic acid contents and the decrease of pH/dry matter loss/ammonia-N. The increased rumen fluid dosage (0, 1, 3, 5, and 7 g/100 g wet sweet sorghum) and prolonged ensiling period (∼60 days) reduced the contents of acid detergent fiber, neutral detergent fiber, cellulose and hemicellulose, while elevating the abundance of beneficial Lactobacillus in silages. Lignin was effectively reduced at 60 days of ensiling with the maximum rumen fluid dosage of 7 g/100 g. Significant positive correlations between lactic acid content and the abundance of Lactobacillus (rs=0.866 with P＜0.01) throughout the entire ensiling process for 60 days was found, which resulted in pH decrease to 3.74⁓3.53 for all the bioaugmented silages indicating good quality of silages. In addition, the ensiling also had a positive impact on the improvement of enzymatic hydrolysis efficiency. The bioaugmented silages with rumen fluid loading of 7 g/100 g achieved the highest 72-h enzymatic hydrolysis yield of 79.5%. Thus, the bioaugmented ensiling with rumen fluid offered dual benefits of preservation and pretreatment for sweet sorghum.