Enhancing Rehydrated Rice Husk as Ruminant Feed via Silage Additives: An In Vitro Study

Rice husk is an abundant agricultural by-product with limited use in ruminant feeding due to its high lignocellulosic content and low digestibility. This study compared biological, enzymatic, and chemical additive strategies for improving the ensiling characteristics, chemical composition, and in vitro rumen fermentation of rehydrated rice husk. The experiment was conducted using a completely randomized design with seven treatments: Control (no additive); molasses + Lacticaseibacillus casei TH14 (MB); Acremonium cellulase (AC); laccase (LC); AC + LC; AC + LC + MB; and chemical treatment (CM). After 30 days of ensiling, CM reduced fiber contents and increased in vitro dry matter digestibility (IVDMD) and total volatile fatty acid concentrations (p < 0.05). Among the biological additives, MB and AC + LC + MB significantly reduced NDF and improved ensiling quality and IVDMD (p < 0.05). Notably, AC + LC + MB resulted in the lowest methane emission intensity (44.07 mg/g IVDMD). Although CM, which was included as a chemical-disruption benchmark, was the most effective approach for substrate solubilization, AC + LC + MB improved fermentation characteristics, in vitro digestibility, and methane emission intensity per unit of digested dry matter under the present in vitro conditions.