Biological activities of pennyroyal (Mentha pulegium L.) in broilers

This study was conducted to determine the effects of dietary pennyroyal (Mentha pulegium L.) levels (0, 0.25 or 0.50%) on the growth performance and Escherichia coli and lactic acid bacteria count in the jejunum of broilers. A total of 150 broiler chicks (Ross 308), obtained from a commercial hatchery at 1 day of age, were allocated to 3 dietary treatments (5 replicates each), each treatment with 10 birds per replicate in a completely randomized experimental design. All the birds were housed in batteries from 1 to 21 days, then in grower broiler pens from 21 to 42 days under standard conditions. The average final body weights and body weight gains were similar in all groups. The addition of pennyroyal to the broilers' feed led to a decrease (P < 0.05) in the feed intake. The gain-to-feed ratios for 0, 0.25, and 0.50% dietary pennyroyal were 1.50, 1.50 and 1.41, respectively. The addition of pennyroyal reduced E. coli count and increased the lactic acid bacteria count of the jejunum (P < 0.01). In conclusion, dietary supplementation of pennyroyal improved feed conversion ratio and lactic acid bacteria count, as well as decreased E. coli count, of the jejunum in broilers.