Objective: This trial was conducted to examine the effect of usage different levels of ethanolic extract of peppermint (Mentha piperita) in drinking water in comparison with an antibiotic growth promoter (Virginiamycin) on the growth performance, and carcass traits of broiler chicks.Methods:virginiamycin, and 0.1, 0.2 and 0.3 % ethanolic extract of peppermint supplemented to drinking water. Body weights of broilers were determined at d 1, 21 and 42, feed intake was determined at the same periods, and feed conversion ratio was calculated accordingly. At day 42, two birds per replicate were slaughtered for the determination of carcass traits. Results: Performance indices were not significantly influenced by the dietary treatments at day 42. Carcass yield increased in broilers supplemented with 0.3 % peppermint extract in drinking water, also, abdominal fat pad decreased in broilers supplemented with 0.3 % peppermint in drinking water (P>0.05).Conclusions:Birds were assigned to 5 treatments: control feed, antibiotic group receiving 5 mg/kg In conclusion, the results of this study showed that addition of 0.3 % ethanolic extract of peppermint to drinking water seem to have a positive influence on broiler performance productive via more carcass yield and decrease abdominal fat deposition.

Objective: The trial involved 240 Ross 308 broiler chicks in order to investigate the effects of Mentha pulegium L. (pennyroyal) on performance, carcass traits and immune responses in broiler chickens. Methods: Birds were assigned to 4 treatments: control feed, antibiotic group receiving 4.5 mg/kg flavophospholipol, and 5 and 10 g/kg pennyroyal powder added to the basal diet. Body weights of broilers were determined at d 1, 14, 28 and 42, feed intake was determined at the same periods, and feed conversion ratio was calculated accordingly. At day 42, two birds per replicate were slaughtered for the determination of carcass traits. Antibody titers against newcastle, influenza viruses and sheep red blood cell (SRBC) were determined. Results: Performance, Internal organ weights and carcass characteristics were not significantly influenced by the dietary treatments at day 42. Humoral immune responses were not affected by dietary treatments.Conclusions:In conclusion, the results of this study showed that addition of pennyroyal powder seem not to have a positive influence on growth performance of broiler chicks.