| dc.contributor.author | Bolivar, Remedios B. | en_US |
| dc.date.accessioned | 2014-10-21T12:37:56Z | |
| dc.date.available | 1998 | |
| dc.date.issued | 1998 | en_US |
| dc.identifier.other | AAINQ36572 | en_US |
| dc.identifier.uri | http://hdl.handle.net/10222/55584 | |
| dc.description | Within-family selection approach was undertaken to improve the growth at 16-weeks in Nile tilapia derived from locally adapted strains. The focus was the development of a selection strategy that will be applicable in conditions with limited facilities. Twelve generations of within-family selection have shown that this approach can effectively improve the growth of farmed tilapias as demonstrated by the selection response that was apparent up to the current generation covered by this study. The genetic trend showed a continuous linear response for body weight at 16 weeks. The regression of mean breeding values on generation number indicates that the expected genetic gain would be about 12% per generation. Based on mixed model methodology, the estimate of the heritability in the base population was 0.38. Genotype-environment interaction under the conditions that were examined in this study was of minor importance to the total variation for final body weight. Although the selection was done in a tank environment, substantial response was also observed in hapas and ponds. Routine selection activity can therefore be based on small facilities like tanks while the production of stock and the grow-out can proceed normally in ponds. | en_US |
| dc.description | On a managerial perspective, it has been found that within-family selection is easy to manage and inbreeding can be kept to a minimum if a structured mating scheme like a rotational mating plan is used. Rotational mating has proven to be easy to apply in association with the within-family selection scheme where a complete pedigree is maintained. The within-family selection approach does not require extensive facilities as would be needed for a presumably more efficient selection approach like combined selection. The choice of a selection procedure, particularly for tilapia aquaculture, is a matter to be decided not only on genetic but also on economic grounds given the prevalent scale of the tilapia industry in Asia, which is highly diverse and small-scale. On-farm selective breeding using a simple, low-cost within-family selection scheme can be practiced by small-scale farmers to manage and improve fish stocks. This will empower farmers to use strains of their choice and not be continually dependent on commercial hatcheries. | en_US |
| dc.description | Thesis (Ph.D.)--Dalhousie University (Canada), 1998. | en_US |
| dc.language | eng | en_US |
| dc.publisher | Dalhousie University | en_US |
| dc.publisher | | en_US |
| dc.subject | Biology, Genetics. | en_US |
| dc.subject | Agriculture, Plant Culture. | en_US |
| dc.title | Estimation of response to within-family selection for growth in Nile tilapia (Oreochromis niloticus). | en_US |
| dc.type | text | en_US |
| dc.contributor.degree | Ph.D. | en_US |
