Effects of rosemary extract on lactation performance,serum biochemical indexes,rumen fermentation parameters,and microbial community in dairy cows

HU Ying; XIA Tian; HE Yuyan; ZHOU Chuanshe; KONG Zhiwei

doi:10.13557/j.cnki.issn1002-2813.2025.23.002

Abstract：This experiment aimed to investigate the effects of dietary supplemented with rosemary extract on the lactation performance,serum biochemical indexes,rumen fermentation parameters,and microbial community in dairy cows.A total of 30 healthy,freshly calved Holstein cows with good physical condition,the same parity,and in the lactation period were selected and randomly divided into two groups,with 15 replicates per group and one cow per replicate.The control group was fed a basal diet,while the experimental group received the basal diet supplemented with 20 g/(head·d)of rosemary extract.The pre-trial period was 18 days,and the formal trial period was 30 days.The results showed that compared with the control group,there were no significant differences in milk yield,milk fat percentage,milk protein percentage,lactose percentage,and somatic cell count in the experimental group(P>0.05).The levels of urea nitrogen(BUN),glucose(GLU),and blood ammonia(BA)were significantly reduced(P<0.05),and triglyceride(TG)was extremely reduced(P<0.01),and the non-esterified fatty acid(NEFA)content in the serum of the experimental group was extremely increased(P<0.01).The propionic acid content in the rumen fluid of the experimental group was significantly increased(P<0.05),while the acetic acid content and acetic acid to propionic acid ratio were significantly decreased(P<0.05).There was no significant difference in alpha diversity between the two groups(P>0.05).At the genus level,the relative abundance of Rikenella in the experimental group was significantly increased(P<0.05),while the relative abundances of Lentimicrobium and Eisenbergiella were significantly decreased(P<0.05).The study shows that dietary supplementation with rosemary extract can improve rumen fermentation function and lipid metabolism of dairy cow by modulating the rumen microbial structure.