Dietary β-sitosterol regulates serum lipid level and improves immune function, antioxidant status, and intestinal morphology in broilers

Abstract

This research investigated effects of dietary β-sitosterol addition at different levels on serum lipid levels, immune function, oxidative status, and intestinal morphology in broilers. One-day-old broiler chicks were allocated to 5 groups of 6 replicates. Chickens in the 5 groups were fed a basal diet supplemented with 0 (control group), 40, 60, 80, and 100 mg/kg of β-sitosterol for 42 D, respectively. β-Sitosterol linearly decreased ( P < 0.05) concentrations of serum total cholesterol, jejunal tumor necrosis factor α ( TNF-α), and ileal interleukin 1β ( IL-1β) and mRNA relative expressions levels of jejunal TLR4 and ileal MyD88, whereas it linearly increased ( P < 0.05) contents of jejunal immunoglobulin G ( IgG), ileal secreted IgA and glutathione, jejunal catalase activity and Nrf2 mRNA relative expression level, villus height ( VH), and VH-to-crypt depth ( CD) ratio ( VH:CD) in the jejunum and ileum. Linear and quadratic increases ( P < 0.05) in absolute and relative spleen weight were observed by dietary β-sitosterol, whereas malondialdehyde ( MDA) concentration in the jejunum and ileum followed the opposite trend ( P < 0.05). Compared with the control group, dietary β-sitosterol at higher than or equal to 60 mg/kg level decreased ( P < 0.05) contents of serum total cholesterol, ileal MDA, and jejunal TLR4 mRNA relative expression level, whereas it increased ( P < 0.05) absolute spleen weight and ileal glutathione content. Higher than or equal to 80 mg/kg level of β-sitosterol enhanced ( P < 0.05) jejunal IgG concentration, VH, catalase activity, and Nrf2 relative expression level and ileal secreted IgA content, but reduced ( P < 0.05) ileal IL-1β content and MyD88 mRNA relative expression level. β-Sitosterol addition at 60 and 80 mg/kg levels increased ( P < 0.05) relative spleen weight, whereas it decreased ( P < 0.05) jejunal MDA accumulation. Moreover, 100 mg/kg level of β-sitosterol reduced ( P < 0.05) jejunal TNF-α level, but it increased ( P < 0.05) VH in the jejunum and VH:CD in the jejunum and ileum. Accordingly, dietary β-sitosterol supplementation could regulate serum cholesterol level, promote immune function, and improve intestinal oxidative status and morphology in broilers.