Efficacy of 17 α‐methyl testosterone and letrozole on sex reversal of protogynous grouper, Epinephelus tauvina (Forskal, 1775) and spawning performance of sex‐reversed males
2015
Ranjan, Ritesh | Xavier, Biji | Dash, Biswajit | Edward, Loveson L | Suresh, Relangi D | Kumar, Pilli Suresh
This study aimed to test the efficacy of 17 α‐methyl testosterone (17 α‐MT) alone and in combination with letrozole, an aromatase inhibitor, for the induction of sex reversal in protogynous greasy grouper, Epinephelus tauvina. Further, the long‐lasting effects of these treatments and spawning performance of sex‐reversed males were also investigated. Greasy grouper with oocytes in the perinucleolus stage were implanted with 5 mg 17 α‐MT kg⁻¹ body weight (T₁), 5 mg 17 α‐MT and 0.2 mg letrozole kg⁻¹ body weight (T₂) and 5 mg 17 α‐MT with 0.4 mg letrozole kg⁻¹ body weight (T₃) and no androgens/enzyme inhibitor implanted (C). The 17 α‐MT alone and in combination of letrozole‐induced sex reversal in greasy grouper, whereas untreated control fish (C) showed normal ovarian development. However, T₂ and T₃ group showed 100% sex reversal and completion of spermatogenesis up to functional male phase in 2 and 3 months, respectively, whereas T₁ group resulted in only 66.67% functional male with motile spermatozoa after 4 months. Sex‐reversed males successfully fertilized the eggs during induced spawning. There were significant differences on fertilization and hatching rates between T₂ group (79.00 ± 4.36%; 77.67 ± 2.87%, respectively) and T₁ group (57.67 ± 3.17%; 63.87 ± 2.91%, respectively). The result suggested that 17 α‐MT (5.0 mg kg⁻¹ BW) in combination with letrozole (0.2 mg kg⁻¹ BW) has the potential to produce 100% sex‐reversed male in short period in greasy grouper, which might greatly help in seed production of greasy grouper.
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