Effect of mixed use of thyme and fennel oils on biochemical properties and electrolytes in rainbow trout as a response to Yersinia ruckeri infection

The aim of study was to compare the effects of supplementation of food with herbal oils (Thymus vulgaris and Foeniculum vulgare) on biochemical properties and electrolytes of rainbow trout infected with Yersinia ruckeri. In total, 120 healthy fish (mean weight 84 +/- 1.02 g) were equally divided into four experimental groups. The experimental study was carried out for one week. The first group was control without supplementation and infection, the second group was infected and without oil supplementation, the third group was supplemented with oils (10 ml.100 g(-1) rates) for one week and infected with Y ruckeri and the last group was oil supplemented without infection. Results indicated that fish fed with dietary supplements showed enhanced bactericidal activity, total protein, albumin, cholesterol, triglyceride and bilirubin compared to the control (P < 0.05). As the value of herbal oils was increased in diets, the plasma glucose level decreased. The levels of K, Na, Ca, and Mg increased whereas Cl values decreased, compared to the control. It can be concluded that diet supplementation with herb oils used in this study can increase disease resistance by increasing levels of some biochemical parameters and electrolytes in rainbow trout to Y ruckeri infection.