Influence of procyanidin supplementation on the immune responses of broilers challenged with lipopolysaccharide

In the present study, the effect of dietary procyanidin (PCA, from pine needles) supplementation on the innate immunity of broilers were investigated. The experiment was designed as a 2 × 4 factorial arrangement (eight cages / treatment; six birds (one‐day‐old) / cage) with dietary PCA concentrations (0, 0.05, 0.075 and 0.1%) and two immune treatments (injection of lipopolysaccharide (LPS) (0.5 mg/kg body weight) or saline). LPS was dissolved in sterile 9 g/L (w/v) NaCl solution at 16, 18, 20 days of age to mimic immune stress. The remaining birds were injected with saline as a placebo. The results indicated that, prior to LPS challenge, the PCA diet had no significant effect on bird growth performance. The injection of LPS was also not associated with any significant changes in poultry performance. LPS injection increased the activity of nitrogen oxides (NOx) and the concentrations of inflammatory cytokines (interferon‐γ (IFN‐γ), interleukin‐1β (IL‐1β), IL‐2, IL‐4, IL‐6 and IL‐10) in serum; dietary PCA decreased these concentrations (P < 0.05) in the PCA 0.1% group, further illustrating the immune effect of PCA. In conclusion, PCA supplementation has a beneficial effect on LPS challenge, which may be associated with the inhibition of the secretion of cytokines and decrease in the proinflammatory marker NOx.