Dietary Dracocephalum kotschyi essential oil improved growth, haematology, immunity and resistance to Aeromonas hydrophila in rainbow trout (Oncorhynchus mykiss)

In the present study, the effect of Dracocephalum kotschyi essential oil (DKE) was investigated on growth, haematology, immune and antioxidant defence system and resistance of rainbow trout juveniles to bacterial infection (Aeromonas hydrophila). For this purpose, the fish were fed a diet containing different concentrations of DKE including 0 (control), 0.2, 0.25 and 0.3 mg/kg diet in three replicates for 60 days. After feeding trial, the fish were challenged with a pathogenic dose of A. hydrophila. Based on the results, immune components in plasma (alternative complement activity [ACH50], IgM content, lysozyme activity, total protein and total albumin) and mucus (protease activity, IgM content and lysozyme activity) significantly elevated in fish fed diet containing 0.2 and 0.25 mg DKE/kg diet compared with other groups (p