Effects of sodium selenite addition amount on in vitro rumen fermentation and microbial composition of dairy cows

YANG Jing; CHEN Zhen; SUN Lu; ZOU Aling; QIU Yaqi; ZHOU Xiaojie; ZHAN Kang; LIN Miao

doi:10.13557/j.cnki.issn1002-2813.2025.21.004

Abstract：The experiment aimed to investigate the effects of sodium selenite addition amount on the in vitro fermentation characteristics and microbial composition of dairy cows.Three Holstein cows were used as rumen fluid donors.Sodium selenite at concentrations of 0,0.075,0.150,0.300,0.750,1.500 and 15.000 mg/kg(based on selenium)was added to the basic fermentation substrate to conduct in vitro simulated fermentation.The results showed that as the fermentation time increased,the gas production in each treatment group gradually increased.Compared with the absence of sodium selenite,the addition of sodium selenite significantly or extremely significant reduced the concentrations of acetic acid,isobutyric acid,valeric acid,caproic acid and total volatile fatty acids(P＜0.05 or P＜0.01).Rumen microbiota analysis revealed that compared with the absence of sodium selenite,the relative abundances of norank_f＿Ruminococcaceae,Christensenellaceae_R-7_group,Lachnospiraceae_NK3A20_group,and Anaerovorax in the group with 0.300 mg/kg sodium selenite were significantly increased(P＜0.05).The relative abundances of norank_f＿Ruminococcaceae,Christensenellaceae_R-7_group,Lachnospiraceae_NK3A20_group,and Anaerovorax in the groups with 0.750,1.500 and 15.000 mg/kg sodium selenite were lower than those in the group with 0.300 mg/kg sodium selenite,and the relative abundance of Desulfovibrio was extremely significant higher than that in the group without sodium selenite addition(P＜0.01).The study indicates that sodium selenite has an important regulatory effect on the in vitro fermentation process and microbial community structure of dairy cows,but adding amounts higher than 0.750 mg/kg may have negative effects.