The effect of different level of Mentha piperita on growth performance, body composition, Intestinal bacteria and survival rate of Oncorhynchus mykiss in challenging with Yersinia ruckeri

This study was conducted to evaluate the effects of different levels of Mentha piperita extract on growth factors, body composition, intestinal bacteria and survival rate of Oncorhynchus mykiss in challenging with Yersinia ruckeri. For this purpose, four groups of fish with mean weight of 32. 2± 0.12 g were raised for 8 weeks in Vniro tanks, 80 fish to each tank and feeding with different levels of M. piperita (with concentrations of % 0, % 1, % 2.0 and % 3.0, 3 replicates for each treatment). At the end of the trial, growth factors, intestinal bacteria and survival rate of fish in challenging with Y. ruckeri were determined in different groups. Results showed that O. mykiss fed on a diet supplemented with 3% M. piperita had significantly higher growth factors, lactic acid bacteria, and survival rate compared to other treatments (P<0.05). Although, the study of body composition showed no significant difference between different treatments (P>0.05). Based on the results, using of M. piperita extract, especially at the level of 3 % can improve the growth performance and survival rate of O. mykissmykiss in challenging with Y. ruckeri and was recommended in the diet.