Effect of synthetic male hormone on phenotypic sexual differentiation of Nile tilapia (Oreochromis niloticus) [eclectronic resource].

Includes references.

The effect of the synthetic male hormone 17 a-methyltestosterone (MT) on phenotypic sexual differentiation in Nile tilapia Oreochromis niloticus was studied. Fourty five hundreds sexually undifferentiated Nile tilapia fry were divided into four experimental groups and control, 60 ppm MT was added to the feed and fed to 7 -day old fry for the 1st and 2nd groups, and for 14-day old try for the 3rd and 4th groups. The hormonal treatments were terminated after application. Fry were fed at approx. rate of 20% of body weight twice daily. At 100 days of age fish were dissected, the gonads were classified on the basis of microscopic appearance. The dissected gonads were stained by aceto-carmine squash method. Ovarian tissue was positively identified by the presence of oo~ cytes. Feeding Nile tilapia (Oreochromis niloticus) fry at 7days of age on diet added to it synthetic male homwne resulted in higher body weight, total body length, body weight gain, growth rate and survival rate then control. The hormone treatment resulted in male population ranged from 79.4 to 98.9% as compared to 53% for the control.

Summary in Arabic.

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