Effects of condensed tannins in <i>Lespedeza bicolor</i> leaves on <i>in vitro</i> rumen fermentation and methane emissions

Forages containing condensed tannins (CT) have been shown to reduce methane (CH₄) emissions and improve livestock production. This study aimed to evaluate the seasonal variations of <i>Lespedeza bicolor</i> CT and assess their effects on rumen fermentation and CH₄ emissions for better exploitation of <i>L. bicolor</i>. The CT content of <i>L. bicolor</i> leaves during the growing season varied between 156.81 and 250.20 g kg⁻¹ DM. <i>L. bicolor</i> CT significantly reduced CH₄ and ammonia nitrogen production while maintaining <i>in vitro</i> dry matter digestibility. <i>L. bicolor</i> leaves harvested at the vegetative stage exhibited the highest nutritional value, with the most pronounced effects on improving rumen fermentation. <i>L. bicolor</i> CT can effectively improve rumen fermentation and reduce CH₄ production. <i>L. bicolor</i>, especially the leaves at the vegetative stage, could be strategically used as a CH₄-mitigating feed supplement in ruminant production. These findings will help to utilise tannin-containing shrub legumes as new feed resources and contribute to the development of animal husbandry and mitigation of global climate change.