Induction of mono-sex (male tilapia) population by inter-specific hybridization and hormonalsex revesal of Nile tilapia.

Abstract

The present study. was planned with the aim to determine the optimal dose of oral administration of the androgen 17-α methyl testosterone (MT) for effective sex reversal, of Nile tilapia as well as comparing growth performance and feed utilization, proximate body composition and human food safety of hybrid blue tilapia Oreochromis aures X O. niloticus (T1), normal (T2) and sex reversed Nile tilapia, O. niloticus (T3 , T4 and T5). All treatment groups that received androgen, 17 α methyl testosterone (MT) showed sex reversal in Oreochromis niloticus, with a significantly higher male proportion than female as compared to the control. The dose level of oral administration of 60 mg MT/ kg of feed for 28 days to Oreochromis niloticus resulted in maximum male sex ratio. The treatment groups (T2), that received 60 mg MT for 28 days exhibited the best feed utilization in terms of FCR, PER, PPV% and EU% and in turn growth performance in terms of AFW, AWG, ADG, SGR (%/ day)and survival rates. With regard to hman food safety, tilapias rapidly excrete ingested hormone, with MT levels falling to less than 1% within 100 hours of withdrawing MT. Thus MT was not detectable in adult tilapias, which require a grow-out period of at least five to eight months to reach international marketable size. From the results of the present study it can be concluded that, the use of 60 mg/ kg MT produced statistically higher male sex percentage when done for 28 days post hatch with efficient feed and protein utilization and in turn attaining higher growth performance, survival rates and human safety.