Study of synergistic effect of potassium- sorbate and Lactobacillus casei on the growth performance, hematological parameters, body composition and intestinal flora of rainbow trout fry (Oncorhynchus mykiss Walbaum, 1792)

This study focused on investigating the synergistic effects of potassium sorbate and Lactobacillus casei in rainbow trout fry (Oncorhynchus mykiss) with the initial weight of 2.45±0.05.A completely random designed experiment was carried out for 8 weeks using six treatments, including: commercial diet (control), diet 107 CFU/ g bacteria (treatment 1), a diet containing 0.5% of potassium sorbate (treatment 2), a diet containing 1% potassium sorbate (treatment 3), the composition of the diet with %0/5 of potassium sorbate and 107 CFU/ g Lactobacillus casei (treatment 4), and the composition of the diet with 1% potassium sorbate and 107 CFU/ g Lactobacillus casei (treatment 5).The results showed that the highest final weight, SGR, FCR and PER were observed in the treatment 4 which revealed significant differences with other treatments (P0/05). WBC was significantly higher (P0/05). In addition, the number of intestinal bacteria and lactobacillus showed significant differences among the different treatments. and highest rate was observed in treatment 4 (P