Efficacy of dietary quercetin supplementation with high-energy diet model in broilers: implications on zootechnical parameters, serum biochemistry, antioxidant status, patho-morphology and gene expression studies

Context Currently, fat supplementation is one of the commonest strategies in poultry production for early economic return. However, it might cause various unidentified metabolic alterations in chickens. Flavonoid compound quercetin has potential to modulate oxidative stress and lipid metabolism. Aim The study was designed to evaluate the effect of dietary quercetin supplementation in broilers challenged with high-energy diet (HED). Methods In total, 192 days old Vencobb-400 broiler chicks were randomly allocated to four dietary treatments with four replicates (12 birds/replicate) per treatment. Four treatments included basal diet without any supplementation (T1), basal diet + quercetin (1 g/kg; T2), HED supplemented with vegetable oil [34 g/kg (2-3 weeks), 35 g/kg (4-6 weeks); T3], HED supplemented with vegetable oil [34 g/kg (2-3 weeks), 35 g/kg (4-6 weeks)] + quercetin (1 g/kg; T4) for the age of 2-3 (starter) and 4-6 (finisher) weeks. Key results Improvement was observed in the growth performance and feed conversion ratio in broilers with the dietary treatments (P <= 0.05). HED-supplemented group showed increased levels of metabolic stress, which was explained by the elevated concentrations of cortisol and malondialdehyde, and reduced serum/liver superoxide dismutase and glutathione peroxidase activity. Moreover, lipotoxicity was found due to the accumulation of fat, and lipid peroxidation caused various injuries to the vital organs such as liver and kidney, which were manifested by histopathological findings, and also upregulated the hepatic inflammatory interleukin (IL)-1 beta, IL-6, and tumour necrosis factor-alpha mRNA expression in the HED group. HED in combination with quercetin attenuates the altered serum metabolic markers, lipid peroxidation with subsequent rising in endogenous enzyme activity. In addition, it exhibited lipolytic action by lysis of accumulated fat and ameliorated the pathomorphic alteration in vital organs and downregulation of hepatic IL-1, IL-6 and TNF-alpha mRNA expression. Conclusions High dietary energy exhibits metabolic alteration and injuries to the vital organs. It is concluded that quercetin has potential to protect against the adverse effects induced by consumption of high-energy diet in broilers. Implications The supplementation of quercetin as an antioxidant seems to be beneficial for poultry production as an herbal feed additive for better performance, production, and health status.