Altering the adhesion of rumen microbiota and improving rumen digestion of corn stover via steam explosion combined with Lactobacillus plantarum/laccase fermentation

Corn stover (CS) is a type feed resource of ruminants, but the lignocellulose in CS hinders its efficient digestion. In this study, we used steam explosion (SE) combined with Lactobacillus plantarum (Lac)/laccase anaerobic digestion (AD) to improve the ruminal digestion of CS. The experiment used a 2 (SE vs. no SE) multiply 2 (AD vs. no AD) factorial design, and was divided into 6 groups: Control group (CS), Lac fermentation group (CS-Lac), laccase fermentation group (CS-laccase), SE group (SECS), SE combined with Lac fermentation group (SECS-Lac), SE combined with laccase fermentation group (SECS-laccase). The results showed that AD and SE processing effectively decreased the neutral detergent fiber (NDF, P<0.001), acid detergent fiber (ADF, P<0.001) and acid detergent lignin (ADL, P<0.05) contents of CS. SE combined with AD decreased ADL content and increased ADF content of CS (P<0.001). AD improved the 72 h rumen degradation rate of DM, NDF and ADF in CS (P<0.001), SE combined with AD had higher rumen 72 h DM, NDF, ADF degradation rate of CS than AD or SE processing (P<0.001). SE or AD significantly increased the effective degradation (ED) rate of NDF and ADF in CS (P<0.001), SE combined with AD further improved the rumen ED of NDF and ADF in CS (P<0.001). The result of rumen adhered microbiota showed that SE processing changed the rumen adhered microbiota community in CS. The abundance of g__Butyrivibrio was significantly increased (P=0.021) in CS treated with SE processing, while g__Rikenellaceae_RC9_gut_group (P=0.005) and g__norank_f__F082 (P=0.032) were decreased significantly. Correlation analysis results showed that g__Butyrivibrio was positively correlated with rumen degradation parameters of NDF and ADF (P<0.05), while g__Rikenellaceae_RC9_gut_group and g__norank_f__F082 were negatively correlated with rumen degradation parameters of NDF and ADF (P<0.05). In conclusion, SE combined with AD can improve rumen fiber degradation rate of CS and increased the abundance of rumen cellulolytic bacteria.bacteria.