Abstract: This study was conducted to investigate the effects of dietary supplemented with sodium humate (HNa) on the liver tissue inflammation and antioxidant capacity of Salmonella Typhimurium (S. Typhimurium) infected broilers. A total of 320 healthy 1-day-old Arbor Acres broilers were randomly assigned into 5 treatment groups with 8 replicates of 8 birds each, named CON group (basal diet), ST group (basal diet), L-HNa group (basal diet+0.2 g·kg^-1 HNa), M-HNa (basal diet+0.4 g·kg^-1 HNa), and H-HNa group (basal diet+0.6 g·kg^-1 HNa), respectively. On day 22-24, the broilers in the CON group were gavaged with 1 mL of PBS, while the broilers in the ST, L-HNa, M-HNa and H-HNa groups were gavaged with 1 mL of 3×10⁹ CFU·mL^-1 S. Typhimurium, daily, respectively. The trial lasted for 24 days. The results showed that: 1) Compared with the ST group, dietary supplemented with 0.6 g·kg^-1 HNa significantly increased the average daily gain (ADG) (P<0.05) of broilers. 2) Compared with the CON group, livers of broilers in the ST group exhibited lots of inflammatory cell infiltrations and liver index increased, while dietary supplemented with different concentrations of HNa relieved hepatic histopathological damage (P<0.05). 3) The activities of serum alkaline phosphatase (AKP), alanine aminotransferase (ALT), and aminotransferase (AST) were significantly higher in the ST group broilers compared with the CON group (P<0.05). 4) Compared with the CON group, the broilers in the ST group had lower activities of liver catalase (CAT), superoxide dismutase (T-SOD), and total antioxidant capacity (T-AOC) and higher concentration of MDA (P<0.05). Importantly, dietary supplemented with HNa alleviates the damage of S. Typhimurium infection on the antioxidant function of broilers liver. 5) Compared with the ST group, dietary supplemented with different concentrations of HNa significantly decreased the mRNA expression of liver interleukin-1β (IL-1β), IL-18, tumor necrosis factor-α (TNF-α), inducible nitric oxide synthase (iNOS), and cluster of differentiation 68 (CD68) (P<0.05), while significantly increased the mRNA expression of IL-10, arginase-1 (ARG1), and cluster of differentiation 163 (CD163)(P<0.05). 6) Compared with the CON group, S. Typhimurium infection significantly elevated the protein expression of nuclear factor kappa beta p65 (NF-κB p65), NOD-like receptor protein 3 (NLRP3), apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), and Caspase-1 (P<0.05), significantly decreased the protein expression of NF-kappa-B inhibitor alpha (IκBα)(P<0.05). However, dietary administration of HNa inhibited the activation of NF-κB and NLRP3 signaling pathway. In summary, dietary supplementation of HNa alleviated liver damage of broilers caused by S. Typhimurium infection by decreasing liver inflammation response, increasing liver antioxidant function and suppressing activation of NF-κB and NLRP3 signaling pathway in the liver.

Key words: sodium humate, Salmonella Typhimurium, liver inflammation, antioxidant, broiler