Investigation of sexual maturity and change in gonadosomatic index of sex riversed rainbow trout (Oncorhynchus mykiss) treated by oral ۱۷ alpha methyl testosterone

The study was carried out in the genetics and breeding resaerch canter 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 control treatment and one dose of hormone  ۱۷α-Methyltestosterone added to the diet at the rate of ۳ mg per kg food by dissolving in ۲۰۰ ml of ۹۵% ethanol per kg feed.The use of oral administration of ۱۷α-methyltestosterone (۱۷MT) at ۳ mg ۱۷MT/kg of feed for ۷۰ 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 ۱۷α- methyltestosterone was effective in sex riversed of rainbow trout. The results  has shown in nearly ۱۰۰% of the treated animals being males. The GSI index in female and male fish of control group were  ۰.۰۴±۰.۱   and ۰.۰۷±۰.۰۱, respectively (Fig.۳) and significantly different (p≤۵%). But  GSI index  of ۱۰۰% sex riversed male fish of MT treated was ۰.۰۶±۰.۰۱ and hadn,t significantly differene (p≥۵%) with treated group ( genetically male and female).

Keywords:

Onchorynchus mykiss , ۱۷α-Methyltestosteron , Sex reversal , GSI index , XX male