Evaluating the therapeutic effect of different forms of silymarin on liver status and expression of some genes involved in fat metabolism, antioxidants and anti‐inflammatory in older laying hens.

Background: Silymarin, the predominant compound of milk thistle, is an extract took out from milk thistle (Silybum marianum) seeds, containing a mixture of flavonolignans with strong antioxidant capability. Methods: The experiment was conducted using 70 Lohmann LSL‐Lite hens at 80 weeks of age with 7 treatments each with 10 replicates. Treatments included: (1) control diet without silymarin, (2) daily intake of 100 mg silymarin powder/kg body weight (BW) (PSM100), (3) daily intake of 200 mg silymarin powder/kg BW (PSM200), (4) daily intake of 100 mg nano‐silymarin/kg BW (NSM100), (5) daily intake of 200 mg nano‐silymarin/kg BW (NSM200), (6) daily intake of 100 mg lecithinized silymarin/kg BW (LSM100) and (7) daily intake of 200 mg lecithinized silymarin/kg BW (LSM200). The birds were housed individually, and diets were fed for 12 weeks. Results: Scanning electron microscopy showed that NSM was produced with the average particle size of 20.30 nm. Silymarin treatment improved serum antioxidant enzyme activity. All groups receiving silymarin showed a decrease in liver malondialdehyde content, expression of fatty acid synthase, tumour necrosis factor alpha, interleukin 6 (IL‐6) genes in the liver, and hepatic steatosis than the control, except those fed the PSM100 diet. There were decreases in liver dry matter and fat contents, non‐alcoholic fatty liver disease and hepatocyte ballooning, and an increase in glutathione peroxidase gene expression and a decrease in iNOS gene expression in birds fed the NSM100, NSM200, LSM100 and LSM200 diets compared to the control group. Moreover, all groups receiving silymarin showed a significant decrease in liver weight compare to the control group. Conclusions: Overall, the effects of silymarin when converted to NSM or LSM and offered at the level of 200 mg/kg BW were more pronounced on the hepatic variables and may be useful in the prevention of the liver disease in older laying hens. [ABSTRACT FROM AUTHOR]