Issue |
Genet. Sel. Evol.
Volume 37, Number 6, November-December 2005
|
|
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Page(s) | 587 - 599 | |
DOI | https://doi.org/10.1051/gse:2005020 |
DOI: 10.1051/gse:2005020
A combination of walk-back and optimum contribution selection in fish: a simulation study
Anna K. SonessonAKVAFORSK (Institute of Aquaculture Research Ltd), P.O. Box 5010, 1432 Ås, Norway
(Received 2 December 2004; accepted 4 July 2005)
Abstract -
The aim of this paper was to study the performance of a novel fish breeding
scheme, which is a combination of walk-back and optimum contribution
selection using stochastic simulation. In this walk-back selection scheme,
batches of different sizes (50, 100, 1000, 5000 and 10 000) with the
phenotypically superior fish from one tank with mixed families were
genotyped to set up the pedigree. BLUP estimated breeding values were
calculated. The optimum contribution selection method was used with the rate of
inbreeding () constrained to 0.005 or 0.01 per generation. If the
constraint on
could not be held, a second batch of fish was
genotyped etc. Compared with the genotyping of all selection candidates (1000, 5000
or 10 000), the use of batches saves genotyping costs. The results show that two
batches of 50 fish were often necessary. With a batch size of 100, genetic
level was 76-92% of the genetic level achieved for schemes with all fish
being genotyped and thus candidates for the optimum contribution selection
step. More parents were selected for schemes with larger batches, resulting
in a higher genetic gain, especially when all selection candidates were
genotyped. There was little extra genetic gain in genotyping of 1000 fish
instead of 100 for the larger schemes of 5000 and 10 000 candidates. The
accuracy of breeding values was similar for all batch sizes (
0.30),
but higher (
0.5) when all candidates were included. Since only the
phenotypically most superior fish were genotyped, BLUP-EBV were biased.
Compared with genotyping of all selection candidates, the use of batches saves
genotyping costs, while simultaneously maintaining high genetic gains.
Key words: fish breeding / selection / parentage testing / walk-back selection / genetic markers
Correspondence and reprints: Anna.Sonesson@akvaforsk.no
© INRA, EDP Sciences 2005