Effects of probiotics and Fe ion on the growth and survival and body composition of rainbow trout, Oncorhynchus mykiss (Walbaum, 1792) frys

This study was carried out to investigate the effects of probiotics and Fe ion on the growth and survival of rainbow trout, Oncorhynchus mykiss frys. For this purpose, the frys were fed with dry pellets containing various ratios of probiotics and Fe for a period of 30 days after absorption of alevins' yolk sac. The growth and survival parameters were measured every 6 days. According to the results, the values of feed conversion ratio were in lowest values in fish fed by only probiotic [i.e. at the rates of 1% (T-1) and 0.75% (T-2) of dry pellet weight]. In contrast, weight gain percent and specific growth rate were significantly higher in fish fed with only probiotic and combination of probiotics and Fe than in other experimental treatments (P<0.05). Also, there were no significant differences between treatments in terms of survival rates (P>0.05). The body composition data showed the higher levels of ash, total protein and lower levels of moisture and lipid in the probiotic and Feriron solution-receiving treatments than control group, respectively (P<0.5). In conclusion, our results show that dry diets containing only probiotic and a combination of probiotic and Fe have more effects on the growth and survival of rainbow trout frys than dry diets containing only Feriron solution. Also, the Bio-Plus 2B has good effect on improving the carcass quality of rainbow trout frys.