Extrusion puffing and enzymes improve silage performance and in vitro digestibility of sorghum straw by altering microbial composition, volatiles and anti-nutritional factors

Unlike forage sorghum straw, grain sorghum straw has limited digestibility and utilization efficiency as a feed due to higher lignocellulose and anti-nutritional factors. This study investigated the effects of Lactiplantibacillus plantarum (LP), cellulase (CE), xylanase (XE) additives and extrusion puffing (EP) pre-treatment on silage performance, microbial community composition, anti-nutritional factors, and volatiles of grain sorghum straw (four ways of silage individually, without the combined treatment of extrusion puffing and additives). XE as an exogenous additive for sorghum straw silage and EP as a pre-treatment showed better silage performance and higher in vitro digestibility compared to no treatment (CK), LP and CE, with EP having the highest in vitro dry matter digestibility (39.89 %) followed by XE (39.41 %). EP and XE altered the composition of the microbial community by increasing the abundance of microorganisms that may be associated with lignocellulose degradation (unclassified_f_Alcaligenaceae) and decreasing the abundance of undesirable bacteria (e.g. unclassified_f_Enterobacteriaceae and unclassified_f_Erwiniaceae), which improved silage quality. Both extrusion puffing pre-treatment and silage treatment showed good results in reducing tannin and phytic acid content. In addition, volatiles with pungent odor (e.g. Methyl isothiocyanate, Benzoyl isothiocyanate) were significantly reduced after extrusion puffing treatment, improving the odor of the straw. These findings indicate the great potential of XE as an exogenous additive for sorghum straw silage and EP as a pre-treatment in improving the silage performance and utilization of sorghum straw. The results of this study provide a scientific basis for the effective utilization of sorghum straw as silage. ● XE additive and EP pre-treatment altered the bacterial profile of sorghum straw silage. ● EP pre-treatment exhibited optimal in vitro digestibility. ● Both EP pre-treatment and silage treatment effectively abrogated anti-nutritional factors in forages. ● XE is a promising silage additive for improving the quality of silage from agricultural waste straws.