Including genetic relationships in selection decisions: alternative methodologies

Brisbane, J. R.; Gibson, John P.

doi:10.1007/bf00220957

Cited by 6 publications

(1 citation statement)

References 6 publications

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“…Introduction Different genetic improvement schemes for pigs are to be evaluated and compared both for their efficiency in making genetic progress and for their return and profit (or net present value) for the investment made in genetic selection. While alternatives have been relatively well investigated regarding their impact on genetic gain (THIELE, 1983;ENGLISCH and FECHNER, 1983;ROEHE, 1991;BRISBANE and GIBSON, 1995), there have been few studies where costs are taken into aecount. These studies were related mostly to purebred situations (NIEBEL and FEWSON, 1979), whereas selection of lines within a crossbreeding scheme was rarely investigated (TRAPPMANN, 1978;WUENSCH et al, 1998).…”

Section: Zusammenfassungmentioning

confidence: 99%

Genetic and economic evaluation of genetic improvement schemes in pigs. – II. Comparison of selection strategies in a three-way crossbreeding scheme

Wuensch¹,

Nitter

Bergfeld

et al. 2000

Arch. Anim. Breed.

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Abstract. Alternative selection strategies for a three-way cross in pigs (Pietrain as the sire line and Large White boars mated to German Landrace sows to produce the F1-female) are investigated to maximise both genetic gain and profit. The number of nucleus sows in the main female line (German Landrace) can vary within a wide range without noticeable effect on the genetic and economic response. Productive lifetimes of approximately one year are recommended for nucleus boars and sows after the progeny test. Boars mated to produce crossbreds should be used longer, especially in the terminal sire line. F1-sows can have a productive lifetime of more than two years and can be used close to their biological maximum. Four testing schemes are compared and the contribution of the three breeds to the return is evaluated. Testing crossbred animals at a central test Station cannot be recommended. This capacity should be used to test purebred animals. Both monetary genetic gain and profit are higher in a scheme with a self-performance testing of boars at Station, in comparison to a scheme with only progeny testing at Station, by 36 and 68%, respectively. Due to a reduced generation interval, using boars to produce breeding boars straight after their self-performance test leads to a further increase of monetary genetic gain by 5% and profit by 13%. In all schemes, selection in Pietrain leads to the highest return due to the highest gene proportion in and its shorter distance to the terminal product and the therefore faster transfer of genetic gain.

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Section: Zusammenfassungmentioning

confidence: 99%

Genetic and economic evaluation of genetic improvement schemes in pigs. – II. Comparison of selection strategies in a three-way crossbreeding scheme

Wuensch¹,

Nitter

Bergfeld

et al. 2000

Arch. Anim. Breed.

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Balancing selection response and rate of inbreeding by including genetic relationships in selection decisions

Brisbane

Gibson

1995

Theoret. Appl. Genetics

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An iterative selection strategy, based on estimated breeding values (EBV) and average relationship among selected individuals, is proposed to optimise the balance between genetic response and inbreeding. Stochastic simulation was used to compare rates of inbreeding and genetic gain with those of other strategies. For a range of heritabilities, population sizes and mating ratios, the iterative strategy, denoted ADJEBV, outperforms other strategies, giving the greatest genetic gain at a given rate of inbreeding and the least breeding at a given genetic gain. Where selection is currently by truncation on the EBV, with a restriction on the number of full-sibs selected, it should be possible to maintain similar levels of genetic gain and inbreeding with a reduction in population size of 10-30%, by changing to the iterative strategy. If performance is measured by the reduction in cumulative inbreeding without losing more than a given amount of genetic gain relative to results obtained under truncation selection on the EBV, then with the EBV based on a family index, the performance of ADJEBV is greater at low heritability, and is generally greater than where EBV are based on individual records. When comparisons of genetic response and inbreeding are made for alternative breeding scheme designs, schemes which give higher genetic gain within acceptable inbreeding levels would usually be favoured. If comparisons are made on this basis, then the selection method used should be ADJEBV, which maximises the genetic gain for a given level of inbreeding. The results indicated that all selection strategies used to reduce inbreeding had very small effects on the variance of gain, and so differences in this respect are unlikely to affect choices among selection strategies. Selection criteria are recommended based on maximising a selection objective which specifies the desired balance between genetic gain and inbreeding.

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Genetic gain with desired status number in breeding programs: a study on selection effects

Wei¹,

Hansen²,

Dhir³

et al. 1998

Can. J. For. Res.

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Genetic gain and average coancestry or status number was investigated for five selection methods: penalty index selection (PIS), family index selection (FIS), combined between-family and within-family selection (CBW), restricted individual selection (RIS), and combined index selection (RCS). PIS was a function of an individual's breeding value and family contributions, modelled as a stepwise procedure to select superior individuals one by one. A penalty would indicate the need to have low average coancestry or large status number. Breeding populations of unrelated families were investigated by Monte Carlo simulation to examine the genetic response of the five selection methods at a restricted selection intensity and average coancestry. PIS attained the greatest genetic gain, except at the selection limits of maximum genetic gain and minimum average coancestry where PIS might be identical to the other selection methods. FIS and RCS well approximated PIS at high average coancestry. RIS was similar to RCS when the heritability was high, particularly at low average coancestry. CBW attained the least genetic gain among the selection methods. For all selections, high heritability would contribute to a greater genetic gain and status number or low average coancestry. PIS was applied to a practical breeding program in Alberta that included several subpopulations. The results suggested that the selection efficiency for balancing genetic gain and average coancestry would increase when deploying a subpopulation strategy for breeding population management.

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Including genetic relationships in selection decisions: alternative methodologies

Cited by 6 publications

References 6 publications

Genetic and economic evaluation of genetic improvement schemes in pigs. – II. Comparison of selection strategies in a three-way crossbreeding scheme

Genetic and economic evaluation of genetic improvement schemes in pigs. – II. Comparison of selection strategies in a three-way crossbreeding scheme

Balancing selection response and rate of inbreeding by including genetic relationships in selection decisions

Genetic gain with desired status number in breeding programs: a study on selection effects

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