AUTHOR=Bai Xue , Shi Yu , Tang Lipeng , Chen Li , Fan Huimei , Wang Haoding , Wang Jie , Jia Xianbo , Chen Shiyi , Lai Songjia 

TITLE=Heat Stress Affects Faecal Microbial and Metabolic Alterations of Rabbits

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.817615

DOI=10.3389/fmicb.2021.817615

ISSN=1664-302X

ABSTRACT=<p>Heat stress can impair the rabbit immune system, induce oxidative stress, and cause many complications. These diseases are characterized by metabolic disorders, but the underlying mechanism is unknown. As a result, the current research determines the effects of HS on intestinal microorganisms in rabbits and the metabolic pathway disorders caused by HS. Twelve rabbits were randomly assigned to one of two groups: CON (22–24°C) and HS (30°C–32°C). Both the groups were treated for 15 days. Blood and fecal samples were collected on day 15. Serum immune oxidation indices were determined using a commercial ELISA kit, and the microbiome of rabbit feces was studied using 16S rRNA gene sequencing. Non-targeted metabolomics was analyzed using ultra-high-performance liquid chromatography-mass spectrometry (UHPC MS/MS). The findings revealed that HS significantly increased IgG and T-AOC levels in serum, whereas it decreased TNF-α and IL-10. NMDS analysis revealed a substantial difference in bacterial community composition between HS and CON groups. At the phylum level, the abundance of <italic>Firmicutes</italic>, <italic>Protobacteria</italic>, and <italic>Verrucomicrobiota</italic> was significantly higher in the HS group, whereas the abundance of <italic>Bacteriodota</italic> was reduced in the CON group. <italic>V9D2013 group</italic>, <italic>Haloplasma</italic>, <italic>Comamonas</italic>, <italic>Clostridium sensu stricto 1</italic>, <italic>Ruminiclostridium</italic>, <italic>Syntrophus Lutispora</italic>, at the genus level <italic>Syntrophorhabdus</italic>, <italic>Paeniclostridium</italic>, <italic>Clostridium sensu stricto 6</italic>, <italic>Candidatus Caldatribacterium</italic>, <italic>Spirochaeta Synergistaceae</italic>, <italic>Syner-01</italic>, <italic>[Eubacterium] xylanophilum group</italic>, <italic>Cellulosilyticum</italic>, <italic>ADurb.Bin120</italic>, and <italic>Devosia</italic> were significantly upregulated in the HS group. The metabolism of the HS group was considerably upregulated compared with the metabolism of the CON group, according to principal component analysis (PCA) and least-squares discriminant analysis (PLS-DA). HS increased the concentrations of 4-pyridoxic acid, kynurenine, 20-OH-leukotriene B4, and dopamine and decreased the concentration of pyridoxal. In the rabbit gut, these compounds primarily impact the metabolic pathways of vitamin B6, tryptophan, neutrophil activation, and prolactin. 4-Pyridoxic acid, pyridoxal, kynurenine, 20-OH-leukotriene B4, and dopamine are essential inflammatory response markers and oxidative stress.</p>