Resveratrol Attenuates Heat Stress-Induced Impairment of Meat Quality in Broilers by Regulating the Nrf2 Signaling Pathway

SIMPLE SUMMARY: Broilers easily experience heat stress (HS), especially in summer, due to a lack of sweat glands. HS has unfavorable effects on the production efficiency, meat quality, antioxidant capacity, and welfare of broilers, which can be mitigated with nutritional strategies. Resveratrol (RES) has been found to mitigate the HS-induced decrease of antioxidant capacity in muscle and, therefore, improve the meat quality of broilers under HS. Nevertheless, there are few reports on the mechanism of action of RES on meat quality and antioxidant status in the muscle of broilers subjected to HS. Our study demonstrated that RES could improve the antioxidant ability of muscle in broilers under HS by activating the Nrf2 signaling pathway and ultimately relieving the HS-induced deterioration of meat quality. ABSTRACT: Studies have indicated that dietary resveratrol (RES) improves the meat quality of broilers subjected to heat stress (HS), but the mechanism of action remains unclear. Therefore, the main purpose of this study was to investigate the effect of RES on meat quality, muscle antioxidant status, and its mechanism of action in broilers under HS. A total of 162 male AA broilers at 21 days old with similar weight were randomly assigned to 3 treatment groups with 6 replicates each. The control group (ambient temperature: 22 ± 1 °C) and HS group (ambient temperature: 33 ± 1 °C for 10 h a day from 8:00 to 18:00 and 22 ± 1 °C for the remaining time) were fed a basal diet and the HS + RES group was fed a basal diet with 400 mg/kg RES. The feeding was conducted for 21 continuous days. The results indicated that HS decreased final body weight (BW), average daily gain (ADG), average daily feed intake (ADFI), breast and leg muscle yield, a*(24h), pH(24h), the activities of catalase (CAT), glutathione S-transferase (GST) and glutathione peroxidase (GSH-Px), and mRNA levels of nuclear factor erythroid 2–related factor 2 (Nrf2), heme oxygenase-1 (HO-1), NADPH quinone oxidoreductase 1 (NQO1), and GSH-Px (p < 0.05). HS also increased b*(45min), L*(24h), drip loss, malondialdehyde (MDA) content, and kelch-like epichlorohydrin-associated protein 1 (Keap1) mRNA level (p < 0.05). Compared with the HS group, the HS + RES group exhibited a higher ADG, breast and leg muscle yield, a*(24h), pH(24h), activities of GST and GSH-Px, and mRNA levels of Nrf2, HO-1, and NQO1 but had lower drip loss and Keap1 mRNA level (p < 0.05). RES can improve meat quality and the muscle antioxidant ability of heat-stressed broilers by activating the Nrf2 signaling pathway.