| Author | Jamjun Pechsiri |
| Call Number | AIT Diss. no.AQ-05-03 |
| Subject(s) | Nile tilapia
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| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Technical Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. AQ-05-03 |
| Abstract | Growth and energetic efficiency of diploid (2n) and triploid (3n) sex reversed male and female Nile tilapia were tested to evaluate whether an increased number of chromosomes in triploids has resulted in physiological superiority, faster growth rate and higher feed utilization. The study consisted of four experiments. Experiment one was designed to compare growth and feed utilization of 2n and 3n sex reversed male and female Nile tilapia at 1%, 3% body weight (BW day") and apparent satiation feeding levels in a freshwater recirculation system comprising of thirty-six 1 m3 concrete tanks. Experiment 2 compared energetic efficiency and energy budget of 2n and 3n sex reversed male and female Nile tilapia at satiation feeding level in twelve respirometer chambers. Growth and feed utilization of 2n and 3n sex reversed male and female Nile tilapia at 20, 25 and 30 mg protein per KJ was compared in a freshwater recirculation system comprising of thirty-six 1 m3 concrete tanks in experiment 3. Experiment 4 compared to compare growth of 2n and 3n sex reversed male and female Nile tilapia cultured communally in freshwater recirculation system comprising six 1 m3 concrete tanks. Triploid Nile Tilapia were produced by subjecting fertilized 2n tilapia eggs to a heat shock for 3.5 min at 41 °C, five minutes after artificial insemination. All diploid and triploid eggs were artificially incubated. After hatching, the sexes of diploid and triploid fish were sex reversed to either all-male or all-female populations by oral administration of 17 a methyltestosterone (60 mg kg" feed) or ethynylestradiol (100 mg kg 1 feed), respectively. Experiment 1 revealed that there growth was significantly higher with increased ration levels in both male and female groups. There were no significant differences in final body weight, specific growth rate (SGR), survival rate, feed conversion ratio (FCR) and protein efficiency ratio (PER) between diploid and triploid fish. Triploids had lower gonad weights than diploids, and this was particularly evident at the satiation feeding level. Triploids had a significantly higher apparent net protein utilization (ANPU) and percentage of gutted weight than diploids at all feeding levels. Experiment 2 showed that male fish requires higher energy for maintenance than female fish. Maintenance energy requirement was not affected by ploidy. Female fish require higher energy for metabolism than male fish. Diploid males had lower feed consumption than diploid and triploid females but sex and ploidy did not affect energy absorption efficiency (A/C). gross growth efficiency (P/C) and metabolic efficiency (R/C) significantly. Mean A/C, P/C and P/A ratios ranged between 82.9-83.8 %, 19.4-21.6% and 23.2-26.1%, respectively. Experiment 3 demonstrated that P:E ratio examine had no effect on growth rate, survival rate, gutted fish and carcass protein of diploid and triploid fish. Males had significantly higher growth rate than females at 25 and 30 mg P KY' diet. Protein utilization efficiency (PER and ANPU) and carcass lipid content were negatively correlated with dietary P:E ratio. The optimum dietary P:E ratio for diploid and triploid Nile tilapia is appears to be 20 fig P K.V'. Experiment 4 revealed that both diploid males and females grow faster when they are cultured together with 3n counterparts. Significantly higher gutted weight, % gutted weight and lower gonad weight was found in triploid fish than diploid females. The better growth of diploid is probably due to differences in competitive or aggressive feeding behavior, leading to differential food intake favoring the diploids or triploids might be less stress resistance than diploids. Triploid fish are physiologically similar to diploid fish both in terms of assimilation efficiency and in portioning energy for metabolism. However, triploid fish consistently had higher protein utilization efficiency than diploids (Experiments 1 and 3). This, coupled with genetic sterility might be an advantage for commercial tilapia culture but Experiment 4 showed that diploids grow better when cultured communally with triploids. Further research on these aspects is necessary before recommending the use of triploids in commercial aquaculture |
| Year | 2005 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. AQ-05-03 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Aquaculture and Aquatic Resources Management (AQ) |
| Chairperson(s) | Amararatne Yakupitiyage; |
| Examination Committee(s) | Yi, Yang;Rakshit, Sudip K;McAndrew, Brendan J.;Bart, Amrit; |
| Scholarship Donor(s) | Thaksin University and Ministry of University Affairs; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2005 |