Zinc supplementation alleviates heat stress in laying Japanese quail

Abstract

The study was conducted to determine whether zinc supplementation could alleviate the detrimental effects of high ambient temperature (34°C) on egg production, digestibility of nutrients and antioxidant status in laying Japanese quail. Quail (n = 180; 52 d old) were divided into six groups (n = 30/group) and were fed a basal diet or the basal diet supplemented with 30 or 60 mg of zinc (ZnSO4 · H2O)/kg diet. Birds were kept at 22°C and 58% relative humidity (RH). At 13 wk of age, the thermoneutral (TN) groups remained at the same temperature, whereas the heat-stress (HS) groups were kept in an environmentally controlled room at 34°C and 42% RH for 3 wk. Heat exposure decreased egg production in birds fed the basal diet (P = 0.001). Linear increases in feed intake (P = 0.01) and egg production (P = 0.004) and improved feed efficiency (P = 0.01) and egg quality variables (P ≤ 0.05) occurred in zinc-supplemented groups reared under HS conditions. Heat exposure decreased digestibility of nutrients (P = 0.001), and these decreases were ameliorated by zinc supplementation (P ≤ 0.05). Serum vitamin C (P = 0.05), vitamin E (P = 0.01) and zinc (P = 0.001) concentrations increased linearly, whereas malondialdehyde concentrations decreased (P = 0.002) as dietary zinc supplementation increased. No significant differences in any values were observed in the TN groups (P > 0.05). Results of the present study suggest that supplementation with 60 mg zinc/kg diet protects quail by reducing the negative effects of heat stress.