الفهرس 
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Abstract
The present work aimed to study the effects of supplemental extra virgin olive oil (EVOO), lemongrass essential oil (LGEO), gallic acid (GA), Vitamin C (VC), Vitamin E (VE) and betaine (BET) as natural antioxidants on heat stressed parameters of growing rabbits, Growth performance, nutrients digestibility, carcass traits, lipid peroxidation, hematological, and antioxidant status were determined. A total of 84 growing male New Zealand White rabbits were randomly divided into 7 equal groups and received a basal diet without any supplementation (control) or supplemented by 500 mg VC, 200 mg VE, 1000 mg BET, 400 mg LGEO, 500 mg GA or 15 g EVOO/kg diet, for eight consecutive weeks. Results revealed that the overall mean of temperature-humidity index was 84.67± 0.35, reflecting a state of severe heat stress. All tested feed additives were found to have a dwindling effect on rabbit’s rectal, skin and ear temperatures. Additionally, EVOO, VE, VC, BET, GA or LGEO dietary supplementation increased significantly (p< 0.05 and p< 0.01) live body weight and daily body weight gain, but decreased both feed conversion ratio and daily water intake. In particular, BET supplementation significantly improved digestibility of dry matter, organic matter, crude protein and nitrogen free extract and significantly increased the nutritive values. All tested additives evoked significant improvement of antioxidant status, lipid peroxidation, WBC´s and lymphocyte count. The concentration of cortisol was reduced markedly with VC, EVOO, VE and LGEO addition. Plasma T3 and T4 were increased significantly ((p< 0.05 and p< 0.01) with all tested dietary supplements except with GA and LGEO addition. In conclusion, these findings suggested that addition of EVOO, VE, VC, BET, GA or LGEO in growing rabbit’s diet could be used effectively to alleviate negative impacts of heat stress load and improving growth performance, nutrient digestibility, oxidative status, and hemato-biochemical features. Furthermore, among these additives, EVOO, VE, VC and BET achieved the best effects.