Effect of different levels of clove (Syzygium aromaticum L.) essential oil on growth performance and oxidative/nitrosative stress biomarkers in broilers under heat stress

A 49-day fully randomized trial was conducted to investigate the dietary effects of clove (Syzygium aromaticum L.) essential oil (CEO) on growth performance and oxidative/nitrosative stress biomarkers in broilers under heat stress. A total of 288 male broilers (Ross 308) were randomly divided into 6 dietary groups (4 replicates and 12 birds/replicate) and supplemented as follows: (I) Normal control (NC) received only basal diet under normal condition. The rest of the animals were challenged with heat and assigned to the following groups: (II) Heat stress control (HSC) received only basal diet; (III) Standard treatment (ST) received basal diet + vit E (100 ppm); (IV-VI) Herbal treatments (HT) received basal diet + 250, 350, and 450 ppm CEO. Heat stress could significantly decrease the animals' performance and induce severe oxidative/nitrosative stress. The HT at the middle dose could significantly improve body weight, body weight gain, and feed intake compared to HSC; however, none of the treatments had a significant effect on feed conversion ratio after inducing heat stress. Moreover, both ST and HT with a trend towards concentration-dependent fashion significantly contributed to normalization of oxidative/nitrosative biomarkers. It appears that CEO is a potential replacement for synthetic antioxidants in broiler diets.