Abstract: 【Objective】 The purpose of this study was to compare the protective effects of porcine bile acid and sheep bile acid on liver and jejunum of heat stressed mice.【Method】 Forty BALB/c healthy male mice aged 7 weeks were randomly divided into blank control group (MOCK group), heat stress group (HS group), heat stress-pig-bile acid group (PBAs group) and heat stress-sheep-bile acid group (SBAs group).Seven days before heat stress, mice in MOCK and HS groups were fed a basal diet, and those in PBAs and SBAs groups were fed the basal diet supplemented with 400 mg/kg pig bile acid and sheep bile acid, respectively.On day 8, mice in MOCK group were placed at room temperature, and mice in other 3 groups were placed in incubators at 36-38 ℃ and 60% relative humidity for 2 h.The blood, liver and jejunum tissues of mice were collected, and the pathological changes of jejunum tissues were observed by HE staining.The content of urea nitrogen (BUN), the activities of alkaline phosphatase (AKP), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum, and the contents of malondialdehyde (MDA), reduced glutathione (GSH) and the activities of superoxide dismutase (SOD) in liver and jejunum tissue were determined by ELISA.The mRNA expression of heat shock protein 60 (HSP60), HSP70 and inflammatory cytokines interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) and IL-10 genes in liver and jejunum were detected by Real-time quantitative PCR.【Result】 Compared with MOCK group, the villus height of jejunum in HS group was extremely significantly decreased (P<0.01), and the crypt depth was significantly increased (P<0.05).The activity of ALT in serum and SOD activity in liver and jejunum were significantly decreased (P<0.05).The relative expressions of HSP60 and HSP70 genes in liver and jejunum were extremely significantly increased (P<0.01).Compared with HS group, villus height, and the ratio of villus height and crypt depth (V/C) in jejunum of PBAs and SBAs groups were extremely significantly increased (P<0.01).ALT activity of serum and SOD activity of jejunal in SBAs group were significantly or extremely significantly increased (P<0.05 or P<0.01). The contents of MDA and GSH, and the relative expressions of HSP60 and HSP70 genes in liver of PBAs and SBAs groups were extremely significantly decreased (P<0.01), while the relative expressions of IL-1β and TNF-α genes were extremely significantly increased (P<0.01).In addition, the relative expression of HSP60 gene in liver and jejunum of SBAs group was extremely significantly or significantly lower than that of PBAs group (P<0.01 or P<0.05), the relative expressions of IL-1β and TNF-α genes in liver were significantly higher than those in PBAs group (P<0.05).【Conclusion】 Under the condition of heat stress, dietary supplementation of sheep bile acid had better effects than that of porcine bile acid on increasing serum ALT activity, improving antioxidant capacity of liver and jejunum, reducing heat shock protein expression and repairing jejunum structural damage, but porcine bile acid had better anti-inflammatory effect than sheep bile acid.

Key words: heat stress; bile acids; injure; protective effect