Monitoring of 17α-methyltestosterone residues in tilapia’s (Oreochromis niloticus) flesh and experimental water after its sex reversal
By: Nadir Boudjlal Dergal, Marie-Louise Scippo, Guy Degand, Vincent Gennotte, Charles Mélard, Sidi-Mohammed El-Amine Abi-Ayad
Key Words: Monitoring, Oreochromis niloticus, 17α-methyltestosterone, Residues, ELISA
Int. J. Biosci. 9(6), 101-113, December 2016.
Tilapias are sexually reversed by hormonal treatment with 17α-methyltestosterone (MT) before introduction in culture unit to avoid over-breeding. This manipulation can be perceived as a real chemical hazard for consumers and environment. Therefore, this study was undertaken to evaluate the withdrawal of MT residues in tilapia’s flesh treated with 65 mg of MT/kg of impregnated-feed for 28 successive days then enlarged for another three months post-treatment. At the 60th day post-treatment, the average of sex ratio in treated groups (97.78% males and 2.22% females) was significantly different (P<0.001) from the untreated one (48.57% males and 51.43% females). MT residues were analyzed using an ELISA method after liquid/solid extraction. The MT content in flesh was very low at the first day post-treatment (1.59 µg/kg), then continued to decrease significantly (P<0.05) and passed below the detection threshold (0.09 µg/kg) after 60 days post-treatment. The MT concentration in water’s samples was below the detection threshold (0.16 µg/kg) and was insignificant from toxicological point of view. So from the data collected it can be suggested that MT treatment of tilapia carries no risk for human health and environment.