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Evaluation of dietary phytochemicals on sex differentiation and growth in Nile tilapia (Oreochromis niloticus)

Rodriguez Montes de Oca, Gustavo Alejandro
http://rave.ohiolink.edu/etdc/view?acc_num=osu1133358425

Abstract Details

2005, Doctor of Philosophy, Ohio State University, Natural Resources.
Monosex tilapia is desirable in aquaculture to control reproduction and produce the gender with faster growth characteristics. Phytochemicals are present in many plants and have many reported biological properties. Here we explore the use of selected phytochemicals as potential in vivo inhibitors of aromatase and as antagonist in nuclear estrogen receptors in gonad germ cells, in order to modulate the gonad differentiation process in sexually undifferentiated Nile tilapia (Oreochromis niloticus). In a first trial, diets were supplemented with genistein (500 mg/kg) and quercetin (10g/kg) along with the androgenic synthetic hormone 17á-methyltestosterone (MT) (60 mg/kg), we evaluated the in vivo response towards masculinization in genetically all-female Nile tilapia. In a second trail, experimental diets with caffeic acid (500 mg/kg), chrysin (500 mg/kg), daidzein (500 mg/kg) including MT (60 mg/kg), along with the steroidal aromatase inhibitor 1,4,6-androstatrien-3-17-dione (ATD) (150 mg/kg), and spironolactone (500 mg/kg), were administered to all-female tilapia to assess the response in final phenotypic sex of the gonad. In this trial, phytochemicals and spironolactone were also administered to all-male tilapia. A control diet, free of chemicals was included in all trials. Our results indicate that the phenotypic sex is not affected by the inclusion of phytochemicals at supplemented levels in the diet. MT and ATD induced masculinization in both feeding trials. Final male ratio with MT was 86 and 100% for experiments 1 and 2 respectively, ATD induced a 50% masculinization. Spironolactone did not affect the phenotypic gender of tilapia. Survival and growth was not different across treatments in experiment 1 and all-male fish in experiment 2. In all-female experiment 2, treatment groups for MT and ATD were significantly smaller (p<0.05). Phytochemical absorption rates were validated with HPLC methods, after adaptation of extraction procedures and chromatographic conditions that allowed estimating concentrations in whole body after administration for either 6 or 8 weeks. Antioxidant biological activity of phytochemicals (quercetin) was also under study; here we explored the possible cumulative effect with ascorbic acid on experimental fish after acute UV-irradiation exposure in order to reduce ascorbic acid depletion in skin tissue, our results indicate no interaction between both antioxidants.
Konrad Dabrowski (Advisor)
157 p.
Tilapia; phytochemicals; sex reversion; MT; ATD; spironolactone; antioxidants

Recommended Citations

Citations

  • Rodriguez Montes de Oca, G. A. (2005). Evaluation of dietary phytochemicals on sex differentiation and growth in Nile tilapia (Oreochromis niloticus) [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1133358425

    APA Style (7th edition)

  • Rodriguez Montes de Oca, Gustavo. Evaluation of dietary phytochemicals on sex differentiation and growth in Nile tilapia (Oreochromis niloticus). 2005. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1133358425.

    MLA Style (8th edition)

  • Rodriguez Montes de Oca, Gustavo. "Evaluation of dietary phytochemicals on sex differentiation and growth in Nile tilapia (Oreochromis niloticus)." Doctoral dissertation, Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1133358425

    Chicago Manual of Style (17th edition)

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