Effect of Dietary Supplementation with Different Levels of Quercetin on Productive, Physiological Performance and Antioxidant Status of Broiler Chickens Reared under Heat Stress

Abstract

The objective of this study was to assess the productive, physiological performance and antioxidant status of broiler chickens under heat stress conditions when fed different levels of quercetin. The total number of one day old broiler chicks used were 144 birds which were randomly allocated in four treatments (36 birds/treatment) and three replicates/treatment. The first, second and third treatments (T1, T2 and T3)  were received  quercetin at a level of 150, 250 and 350 mg/kg of diet respectively. Treatment 4 (T4) was used as control (no supplementation). All experimental treatments were subjected to heat stress conditions. The birds were exposed from the first day until the end of the experiment to temperatures ranging from 38–40°C during the first week and 30–32°C during the final week of the experiment. The results showed that the birds in T2 and T3 treatments had the highest final body weight, body weight gain and there was no mortality in them. They also had increased feed conversion ratio compared to control treatment. The levels of red blood cell count (RBC), hemoglobin concentration (Hb) and packed cell volume (PCV) were higher in the T4 (control) group, but with reduced lymphocyte percentage and increased heterophil percentage and heterophil-to-lymphocyte (H/L) ratio. The results showed a significant increase (P≤0.05) in both mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) in treatments T1, T2, and T3 compared to the control treatment whereas no significant differences were observed in mean corpuscular hemoglobin concentration (MCHC) among all treatments. Moreover, the antioxidant activity results indicated that treatment with T3 had the highest activity of SOD than the control treatment while no difference was observed between the treatments in the activities of GSH-Px, CAT and MDA. Overall, 250 and 350 mg/kg of quercetin supplementation to broiler chickens subjected to heat stress appeared to be the most effective treatments in terms of improved productive, physiological performance and antioxidant status.