Abstract
This investigation focused on how resveratrol (RES) influences egg production, quality, reproductive hormone, and antioxidant capacity in laying hens of different ages. A completely randomized experiment was conducted with a 2 × 2 factorial arrangement of treatments, including 47- and 67-week-old Lohmann Gray laying hens (initial body weight 1.58 ± 0.12 kg) and two dietary treatments (0 and 400 mg/kg RES) for 12 weeks. The study involved 216 hens, randomly allocated with nine replicates per treatment and six hens per replicate. Results indicated that older (67-week old) laying hens exhibited a higher feed-to-egg ratio and defective egg rate during weeks 1 to 12 than 47-week-old without RES supplementation (interaction, P = 0.012 and P = 0.047), while addiction with RES significantly reduced feed-to-egg ratio in 67-week-old hens (P < 0.05). Significant interactions between age and RES were observed for egg quality parameters including albumen height, eggshell strength, and eggshell thickness (P < 0.05). The RES supplementation improved feed efficiency and egg quality (P < 0.05), particularly in older hens. Haugh unit was restored by RES in aged birds during weeks 9 to 12 (interaction, P = 0.023). Plasma levels of melatonin (MT), estradiol (E2), and anti-Müllerian hormone (AMH) also showed significant interactions (P < 0.05), with RES increasing these hormones only in older hens. Age and RES supplementation had a significant interaction for ovarian malondialdehyde (MDA) levels (P < 0.001), where RES significantly reduced MDA concentrations in older hens (P < 0.05). At the molecular level, RES significantly upregulated the mRNA expression of heme oxygenase-1 (HO-1), nuclear factor erythroid 2-related factor 2 (Nrf2), and NAD(P)H quinone oxidoreductase 1 (NQO1; P < 0.01), while aging upregulated tumor necrosis factor-α (TNF-α) expression (P = 0.018). RES also suppressed IL-6, IL-8, TNF-α, and nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) expression, and enhanced anti-apoptotic genes B-cell lymphoma-extra-large and B-cell lymphoma 2 expression (P < 0.05). In conclusion, RES supplementation (400 mg/kg) effectively improved laying performance, egg quality, and oxidative and inflammatory responses in laying hens, suggesting its potential as a nutritional strategy to support laying performance during the late production stages.