The potential benefits ofMentha longifoliaon growth performance and innate immunity parameters in Caspian kutum (Rutilus frisii kutum)

The current research was conducted to examine the benefits ofMentha longifolia(ML) administration through diet on growth performance and haematological, biochemical, and immunological parameters of Caspian kutum (Rutilus frisii kutum). Fish with average weight of 3 g were fed for 8 weeks with diets supplemented with 0%, 2%, 4% and 6% ML-extract. Feeding with 6% ML for 8 weeks significantly improved the growth performance. The highest values in total protein content, protease and esterase activities were observed in the 6% ML. Feeding with 4% and 6% ML led to a significant increase in the alternative complement, respiratory burst activities and total immunoglobulins in blood as well as lysozyme activity in the mucus and serum. The enhancement of skin mucus immune parameters was observed in fish fed with dietary (>= 4%) ML supplement. The mucosal antibacterial effects revealed that the highest ML concentration (6%) had the maximum bacterial growth inhibition zone diameter (mm) and MIC compared with other groups in the study. White blood cell numbers and haematocrit values were significantly higher than in the control groups following the use of 4% and 6% ML. The highest red blood cell counts resulted from the use of 6% ML. Although 4% and 6% ML led to a decrease in the number of lymphocytes, the neutrophils increased after using the same dose, compared with the control group. Triglycerides levels significantly decreased in fish fed with 4% and 6% ML; however, no significant changes were observed in other blood biochemical parameters. Thus, it can be concluded that diets supplemented with ML-extract could significantly impact Caspian kutum by improving growth performance and boosting their immune response.