In vitro comparative analysis of steamed wood and other lignocellulosic substrates on ruminal fermentation and microbiota

Lignocellulosic biomass such as wood is increasingly recognized as a promising low-opportunity-cost feed (LCF) that does not compete with human-edible food. In this study, we evaluated rumen fermentation characteristics and microbial community responses using an <i>in vitro</i> batch culture system with a diverse set of substrates, including steamed and untreated woods, xylo-oligosaccharides, spent mushroom substrates, and conventional feeds. Hierarchical clustering based on bacterial community composition revealed five distinct microbial clusters. Certain steamed woods and xylo-oligosaccharides formed separate clusters from untreated woods and conventional feeds, and were associated with the dominance of specific genera such as <i>Succinivibrio</i> and <i>Selenomonas</i>. These microbial shifts may reflect differences in substrate characteristics, potentially related to hemicellulose- and <i>oligosaccharide</i>-derived components. The results suggest that both steamed wood and xylo-oligosaccharides enhance fermentability and are associated with distinct microbial community structures under <i>in vitro</i> conditions. These substrates show promise as sustainable feed ingredients, and further <i>in vivo</i> studies are needed to evaluate their efficacy and long-term impacts on animal health and productivity.