17 M. J. Agah M. T. Mirakzehi H. Saleh Journal of Animal and Plant Sciences JAPS 20192019/06/01 29 3 657-666 1018-7081 NA <p>The aim of the study was to investigate the effects of olive leaf extract (<em>Olea europea L.</em>) (OLE) and &alpha;-tocopheryl acetate (&alpha;-Toc) on growth performance, nutrient digestibility, blood metabolites and antioxidant activities in heat exposed broiler chickens. Total 200 day-old male Ross 308 chicks were distributed in a completely randomized experimental design, with four treatments and five replicates of 10 birds each.&nbsp;Heat stress was applied for 5 h (33&deg;C) from 28 to 42 days. The treatments were: negative control (without &alpha;-Toc and OLE; NC); a positive control (with 250 mg kg-1 of &alpha;-Toc; PC) and diets with 200 or 400 mg of OLE/kg of diet (OLE1and OLE2, respectively). Heat stress (32&plusmn; 2&deg;C) was applied daily for all the birds. On day 42, blood samples were taken from two birds per replicate. Chromic oxide was used as inert ileal digestibility markers.&nbsp;The evaluated treatments did not significantly affect body weight gain, feed intake and feed conversion ratio. Ileal digestibility of energy, crude ash, Crude Protein, and phosphorus showed a linear increase with supplementation of OLE and &alpha;-toc (p&le;0.05). Cholesterol, triglyceride, Alanine transaminase (ALT) and aspartate aminotransferase (AST) in blood were significantly decreased when chickens were fed diets containing OLE (P &le; 0.05). Plasma lipid peroxidation leve land glutathione peroxidase activities were reduced in chickens fed diets supplemented with OLE and &alpha;-Toc (P &le; 0.05). In conclusion, Supplementation of olive leaf extract to broiler diets as antioxidant components could improve the antioxidant status and reduction in the stressor index of heat stressed broilers.</p> Phenoliccontent,oliveleaf,±-tocopherylacetate,broiler,heatstress Pakistan Agricultural Scientists Forum https://thejaps.org.pk/AbstractView.aspx?mid=2019-JAPS-304