Ultrasound-immersion techniques to improve the efficiency of sex reversal of male tilapia population | |
| Author | Athauda, A. R. S. B. |
| Call Number | AIT Thesis no. AQ-00-25 |
| Subject(s) | Tilapia Hormones, Sex |
| Note | A thesis submitted in paiiial fulfillment of the requirements for the degree of Master of Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. AQ-00-25 |
| Abstract | Recent studies on sex reversal have shown that immersion technique requires substantially shorter exposure period compared to feeding. The present study was conducted in order to determine the best treatment combination using immersion techniques. Furthermore, this study used ultrasound with immersion treatment to achieve high sex mvers1on and more consistent production of mono sex male population of Oreochromis niloticus. The first experiment was carried out as a preliminary study to determine the best immersion duration of one or two hour as for immersion in Methyltestosterone (MT) and Androstenedione (AN) at concentrations of 100 μg/L, 500 μg/L. The second experiment was conducted with immersion solutions of Methyltestosterone (MT), Methyldihydrotestosterone (MDHT) and Trenbolone acetate (TBA) hormones with concentration levels of 50, 100 and 250 ~Lg/L each. The third experiment was ca1Tied out with two hormones, MDHT and TBA 100 μg/L and 250 μg/L each. All the other conditions were similar to experiment two. Immersion periods of 2 h were applied for all treatment combinations of ultrasound, nonultrasound and control. Of the two time periods (1 h and 2 h) applied in the preliminary trial, 2 h immersion resulted in higher (91.75%) and consistent male percentage with ultrasound, while 1 h gave lower (73.5 %) and highly variable results. Both concentrations (100 μg/L, 500 μg/L) of MT and An showed similar results (83%, 82.3%) with ultrasound treatments. Between two hormones, MT resulted in higher male percentage (90.25%) with ultrasound compared to An (75%). Ultrasound immersion resulted 82.63 % males, while non-ultrasound gave 69.5%. In experiment two, ultrasound resulted in significantly higher (P< 0.05) male percentage (96%) than non-ultrasound (87.5). Highest (P< 0.05) percentage of males resulted with ultrasound treated with MT 50, MDHT 100 and TBA 250 μg/L. The male percentages were similar (97, 96, and 96). Without ultrasound treatment, percentage males were 86, 87 and 88. In experiment three, significantly higher (P< 0.05) percentage of male population was found with ultrasound (93.35%) treatments than non-ultrasound (89%) in experiment three. Highest (P< 0.05) percentage of males resulted with ultrasound treated with MDHT 100, TBA 100 and 250 μg/L. The male percentages were 91, 94 and 98, respectively. Without ultrasound treatment, percentage males were 83, 88 and 94. Furthermore rest of the treatment combinations (MT 100 μg/L, MDHT 250 μg/L) also achieved high sex reversal rate, but were not significantly different from non-ultrasound. This study indicated that the ultrasound treatment with immersion was more effective in sex reversal of Oreochromis niloticus than treatment with immersion alone. |
| Year | 2000 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. AQ-00-25 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Other Field of Studies (No Department) |
| Program | Aquaculture and Aquatic Resources Management (AARM) |
| Academic Program/FoS | Aquaculture and Aquatic Resources Management (AQ) |
| Chairperson(s) | Bart, Amrit N.; |
| Examination Committee(s) | Edwards, Peter;Mair, Graham C.; |
| Scholarship Donor(s) | T C D C Netherlands; |
| Degree | Thesis (M. Sc.) - Asian Institute of Technology, 2000 |