ABSTRACT This experiment was conducted to evaluate the effects of supplementary thyme (Thymus vulgaris) essential oil (TEO) and A, C, and E vitamins on performance, egg quality and some biochemical parameters of laying hens under heat stress (HS). A total of 120 White Leghorn laying hens were randomly distributed into 5 experimental groups with 6 replicates and each replicate had 4 laying hens. The HS group was housed at 34°C between 08:00 am and 05:00 pm and the rest of the day at 22°C. The experimental groups were; 1: HS group; 2: HS + TEO (300 mg/kg TEO in diet), 3: HS + TEO + Vit-C (300 mg/kg TEO + 250 mg/kg vitamin C in diet), 4: HS + TEO + Vit-E (300 mg/kg TEO + 250 mg/kg vitamin E in diet), and 5: HS + TEO + Vit-A (300 mg/kg TEO + 15,000 IU/kg vit-A in diet). In the study, body weight, egg weight, feed intake and egg quality of the hens were not affected with treatment groups. Serum glucose level was decreased in the TEO group, plasma MDA was decreased in the TEO and TEO + Vit-C groups and 8-OHdG was decreased in the TEO + Vit-E. It was concluded that it would be more beneficial to use TEO against HS in laying hens with Vit-E and Vit-C instead of using it alone.

中文翻译：

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百里香精油和 A、C 和 E 维生素组合对日粮中热应激下蛋鸡性能、蛋质量、MDA 和 8-OHdG 的影响

摘要 本实验旨在评估补充百里香（Thymus vulgaris）精油 (TEO) 和维生素 A、C 和 E 对热应激 (HS) 下蛋鸡的性能、蛋质量和一些生化参数的影响。将120只白来航蛋鸡随机分为5个实验组，6个重复，每个重复4只蛋鸡。HS 组在上午 08:00 至下午 05:00 之间在 34°C 下饲养，其余时间在 22°C 下饲养。实验组是；1：HS组；2：HS + TEO（饮食中 300 mg/kg TEO），3：HS + TEO + Vit-C（饮食中 300 mg/kg TEO + 250 mg/kg 维生素 C），4：HS + TEO + Vit-E （饮食中 300 mg/kg TEO + 250 mg/kg 维生素 E），和 5：HS + TEO + Vit-A（饮食中 300 mg/kg TEO + 15,000 IU/kg vit-A）。在研究中，体重、蛋重、母鸡的采食量和鸡蛋质量不受处理组的影响。TEO 组的血清葡萄糖水平降低，TEO 和 TEO + Vit-C 组的血浆 MDA 降低，TEO + Vit-E 的 8-OHdG 降低。得出的结论是，在含有 Vit-E 和 Vit-C 的蛋鸡中使用 TEO 对抗 HS 会比单独使用更有益。