Abstract: 【Objective】 This study was aimed to explore the role of transforming growth factor-β 1(TGF-β1)/Smad pathway in liver fibrosis of ascites syndrome in broilers and the prevention and treatment mechanism of compound traditional Chinese medicine water extract.【Method】 258 healthy Ross broilers were routinely raised to 7 days of age and randomly divided into 5 groups:Control group (C),model group (M,multi-factor modeling with low temperature,high-fat and high-protein feed,and high-sodium drinking water),compound traditional Chinese medicine water extract high,medium and low dose groups (T1,T2,T3,based on the model group,added 2.0,1.0 and 0.5 g/kg compound traditional Chinese medicine water extract to drinking water every day,respectively).Clinical symptoms and necropsy changes were observed,HE and Masson staining methods were used to observe the changes of liver tissue structure and collagen fiber deposition in broilers,and the weight at 15,25,35 and 45 days of age were calculated.The relative expression of TGF-β1,transforming growth factor β receptor Ⅰ(TβRⅠ),Smad2,Smad3 and Smad7 genes were detected by Real-time quantitative PCR,and the protein contents of TGF-β1 and TβRⅠ were detected by ELISA in liver at 15,25,35 and 45 days of age.【Result】 Compared with control group,the broilers in model group had enlarged abdomen and fluctuating touch pressure.There was a large amount of light yellow liquid in the abdominal cavity.The liver was congested and swollen,and the texture was brittle,with blutene chloaides on the surface.The liver tissue structure was disordered,and inflammatory cells infiltrated.A large amount of collagen fibers deposited and the liver fibrosis.The body weight in model group was extremely significantly decreased than control group (P<0.01).Compared with control group,expect for TβRⅠ protein at 15 days of age,the relative mRNA expression and protein content of TGF-β1 and TβRⅠ in liver of broilers in model group were significantly increased (P<0.01;P<0.05),the relative expression of Smad2 and Smad3 genes mRNA in liver of broilerss in model group were extremely significantly increased (P<0.01),the relative expression of Smad7 gene mRNA in liver of broilers in model group was extremely significantly decreased (P<0.01).Compared with model group,the results of the compound traditional Chinese medicine water extract groups were improved to varying degrees and high dose group had more significant effect.【Conclusion】 Liver fibrosis was involved in the occurrence and development of ascites syndrome broilers,and the mechanism was related to TGF-β1/Smad pathway.The compound traditional Chinese medicine water extract made from Astragalus,Angelica,Salvia,tuckahoe,licorice,etc.could regulate the TGF-β1/Smad pathway,inhibit the occurrence of liver fibrosis,and effectively prevent ascites syndrome.

Key words: compound traditional Chinese medicine water extract; ascites syndrome in broilers; transforming growth factor β1(TGF-β1); transforming growth factor β receptor Ⅰ(TβRⅠ); Smads