Effects of silymarin on liver function, antioxidant and immune factors of broilers under immune stress

In the context of poultry breeding, pathogenic microorganisms and artificial immune antigens can elicit abnormal immune system responses, leading to diminished growth performance, impaired antioxidant function, and increased inflammatory damage. Silymarin (SM) has been proven to have significant hepatoprotective effects, free radical scavenging ability, and immune regulation function. The purpose of this experiment was to examine how SM protects against Liver injury in immune-stressed broilers. Three Hundred one-day-old ShengZe 901 broilers were split into 5 treatment groups, each with 6 replicates of 10 broilers. Broilers in the control (CON) and lipopolysaccharide treatment (LPS) groups were fed a normal diet, broilers in the 3 SM supplementation (LPS + SM) groups were fed a normal diet adding 0.05%, 0.10%, and 0.15% SM respectively. At 16, 18, and 20 days old, broilers in the LPS and LPS + SM groups were received intra-abdominal injections of 500 µg/kg BW LPS solution. Samples were taken from a broiler in each repetition on day 20, 4 h post-injection, and on the morning of day 28, blood and liver samples were taken to measure antioxidant and inflammation-related indicators. The results showed that adding SM to the diet decreased the serum corticosterone (CORT), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) levels in immune-stressed broilers, and alleviated the hepatocyte necrosis caused by immune stress. Furthermore, adding 0.10% SM to the diet decreased the Liver toll-like receptor 4 (TLR4) mRNA expression on day 20, and decreased the secretion of tumor necrosis factor α (TNF-α), interferon γ (IFN-γ) and interleukin 1β (IL-1β) on day 28. In conclusion, adding SM to the diet improved broilers liver function, reduced pathological damage and inflammatory reactions under immune stress.