The effects of different amounts of Mentha pulegium L. (pennyroyal) on performance, carcass traits, hematological and blood biochemical parameters of broilers

This experiment was conducted to evaluate the effects of different levels of powdered Mentha pulegium L. (pennyroyal; medicinal plant) obtained from its dried aerial part on performance, carcass traits, hematological and blood biochemical parameters of broilers. 300 broiler chicks (Ross 308) were used in a completely randomized design in five treatments and three replicates (20 birds per replicate) for 42 days. The treatment groups consisted of a control group (1) with no Mentha pulegium L. supplementation, and 2, 3, 4 and 5 experimental groups with different levels of Mentha pulegium L. in 0.5, 1, 1.5 and 2% in the feedstuff, respectively. There were significant differences between treatments on performance, carcass traits and blood biochemical parameters of broilers (p<0.05). The lowest amount of daily weight gain (38.82 g) and the highest feed conversion (1.95) were observed in the control group, whereas the highest amount of daily weight gain (46.24 g), the lowest feed conversion (1.71), and the highest breast percent (33.29) were observed in Group 2. The blood samples of Group 5 showed the lowest amount of glucose (157.12 mg/dl) but there was no significant difference between Groups 2 and 5 in the blood glucose levels. The overall results showed that the use of 0.5% of M. pulegium L. medicinal plant in the diets of broilers has positive effects on their performance and carcass traits.   Key words: Antibiotic alternatives, blood metabolites, medicinal plant, Mentha pulegium L.