摘要This study sought to determine the effects of rosemary leaf powder(RP)on laying performance,egg quality,serum indices,gut barrier function,and cecal microbiota and metabolites of late-phase laying hens.A total of 84"Jing Tint 6"laying hens at 65-week old were randomly divided into 2 groups and fed either a basal diet(CON)or a basal diet supplemented with 0.3％RP.Our study revealed that RP improved the Haugh unit and decreased yolk n-6/n-3 polyunsaturated fatty acid(PUFA)ratio of laying hens,increased serum superoxide dismutase(SOD),jejunal activities of SOD and catalase(CAT),and jejunal zonula occludens-1(ZO-1)expression,as well as decreased serum tumor necrosis factor-α(TNF-α)level and jejunal TNF-α mRNA expression.Rosemary leaf powder markedly enhanced(P＜0.05)cecal abun-dances of Rikenellaceae,Rikenellaceae_RC9_gut_group,and Turicibacter,tended to promote(P=0.076)butyrate concentration,and reduced(P＜0.05)cecal abundances of Erysipelatoclostridiaceae,Sutter-ellaceae,Fusobacteriaceae,Campylobacteraceae,Sutterella,Campylobacter,and Fusobacterium,which were closely linked with Haugh unit,yolk n-6/n-3 PUFA ratio,serum SOD and TNF-α.In addition,RP altered the metabolic functions of cecal microbiota and enhanced the abundances of butyrate-synthesizing enzymes,including lysine 2,3-aminomutase,β-lysine 5,6-aminomutase,and 3-oxoacid CoA-transferase.Together,0.3％RP has the potential to enhance egg quality by partially modulating serum antioxidant status,jejunal barrier function,and cecal microbiota structure and metabolites,indicating that RP could be considered a promising feed additive to promote the production performance of late-phase laying hens.