Investigation of sexual maturity and change in gonadosomatic index of sex riversed rainbow trout (Oncorhynchus mykiss) treated by oral 17 alpha methyl testosterone
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Abstract
The study was carried out in the Genetics and Breeding Research Center of Yasouj. All eye-stage eggs were used for the experiment using vertical hatching units to complete hatching. A standard commercial granule feed was used in all experimental groups. The experiment consisted of a control treatment and one dose of the hormone 17α-methyltestosterone added to the diet at the rate of 3 mg per kg of food by dissolving it in 200 mL of 95% ethanol per kg feed.
The use of oral administration of 17α-methyltestosterone (17MT) at 3 mg 17MT/kg of feed for 70 days following the onset of feeding to sex-reverse rainbow trout (Oncorhynchus mykiss) to produce XX males is well established. Examination of the results showed that 17α-methyltestosterone was effective in sex reversal of rainbow trout. The results showed nearly 100% of the treated animals being males.
The GSI index in female and male fish of the control group were 0.04 ± 0.1 and 0.07 ± 0.01, respectively, and were significantly different (p ≤ 5%). However, the GSI index of 100% sex-reversed male fish treated with MT was 0.06 ± 0.01 and did not significantly differ (p ≥ 5%) from the treated group consisting of genetically male and female fish.
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