بررسي كاربرد هورمون 17- آلفا اتينيل استراديول در ماده سازي ماهي قزل آلاي رنگين كمان (Oncorhynchus mykiss)

Effects of 17a-ethinil estradiol on feminization of rainbow trout {Oncorhynchus mykiss)

This study aimed at assessing the effects of 17a-ethinil estradiol on feminization of rainbow trout in the stage of yolk-sac absorption and the relationship between period of immersion and sex reversal percentage. To this end, 400 sac fry larvae were divided equally in 4 separate treatments. The investigation was performed in one stage and in different time periods in a bath containing 400p,g/lit 17a-ethinil estradiol using immersion method. Treatment 1 for 1 hour, treatment 2 for 2 hours, treatment 3 for 4 hours, and treatment 4 for 8 hours were exposed to this hormone. Treatment 5 was used as the control group. In treatment 4, the mortality started after two days and all (100%) of the larvae died after one month; in treatment 3, mortality started after one week and after 40 days, 100% of the larvae died. It is necessary to mention that in both treatments, the larvae absorbed the yolk-sac later that those of the control group. The results indicated that 74.3% of the fish in treatment 1 and 94.4% in treatment 2 were female. The comparison of the results with the sex ratio in the control group that consisted of 35% female fish and 65% male fish showed that immersing sac fry larvae in the bath containing 17a- ethinil estradiol hormone could cause the sex reversal in this group of fish. The mortality rates in both treatments 1 and 2 were completely normal, and similar to the mortality rate in the control group. In all hormone-treated groups, a significant difference in mean weight and length was observed as compared with the control group (p<0.05).