不同降温措施对热应激西门塔尔牛生长性能、肠道微生物区系与代谢物的影响OA

In order to investigate the effects of different cooling measures on growth performance,gut microbiota,and metabolic characteristics of Simmental cattle under heat stress,a total of 100 ten-month-old fattening Simmental cattle weighing(408.90±31.26)kg were randomly assigned to four groups.The control group(FJ)was cooled only by ventilation fans,while the treatment groups were additionally equipped with mist spraying(PW),timed sprinkler cooling(DS),or intelligent vision-based sprinkler cooling(AI)on the basis of ventilation fans.The experimental period lasted 33 d.Growth performance index was measured at the end of the experiment,and fecal samples were collected for gut microbiota and metabolomic analysis.The results showed that compared with FJ group,PW group and DS group,the ambient temperature,relative humidity and temperature-humidity index(THI)of cowshed in AI group were significantly decreased(P<0.01),and the average daily gain was significantly increased(P<0.01).There was no significant difference in α diversity index among groups(P>0.05).There were significant differences in the composition of intestinal flora among groups(P<0.05).At the phylum level,Firmicutes,Bacteroidetes and Patella bacteria were the dominant bacteria in each group.At the genus level,compared with the FJ group,the relative abundance of 9,16,and 15 genera in the DS group,PW group,and AI group changed significantly(P<0.05).Among them,the Lachnospiraceae AC2044 group and the Bacteroidetes RF16 group were significantly enriched in the PW group and the DS group(P<0.05);the Coprococcus and Eubacterium were significantly enriched in the DS group and the AI group(P<0.05);and the Rothia was significantly enriched in the PW group and the AI group(P<0.05).There were 19 differential metabolites in different cooling treatment groups,mainly organic acids,amino acids and fatty acid derivatives,which were significantly enriched in vitamin B6 metabolism,citric acid cycle(TCA cycle),glucagon signaling pathway,alanine,aspartic acid and glutamic acid metabolic,prokaryote carbon fixation pathway,glyoxylic acid and dicarboxylic acid metabolism pathway(P<0.05).This indicates that different cooling measures may alleviate the adverse effects of heat stress in Simmental cattle by modulating gut microbiota composition and metabolic characteristics,thereby promote growth performance,among which intelligent vision-based sprinkler cooling shows a relatively superior cooling effect.