A note on using biased parameter values and non-random mating to reduce rates of inbreeding in selection programmes

Grundy, B.; Caballero, Armando; Santiago, Enrique Rodríguez de; Hill, William G.

doi:10.1017/s0003356100008011

Cited by 51 publications

(36 citation statements)

References 11 publications

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“…The general idea behind these strategies is to reduce the weight given to family information (Villanueva et al, 1994). The simplest method, that can be also applied to BLUP evaluations, is to use a heritability that is upwardly biased (Grundy et al, 1994). With such a simple method, inbreeding can be reduced by up to 30% with only a small reduction in response; however, those procedures can produce some psychological dissatisfaction because they seem to imply that ignorance or false information might be better than true knowledge.…”

Section: Managing the Contributions Of Individualsmentioning

confidence: 99%

Management of genetic diversity in small farm animal populations

Fernández

Meuwissen

Toro

et al. 2011

Animal

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Many local breeds of farm animals have small populations and, consequently, are highly endangered. The correct genetic management of such populations is crucial for their survival. Managing an animal population involves two steps: first, the individuals who will be permitted to leave descendants are to be chosen and the number offspring they will be permitted to produce has to be determined; second, the mating scheme has to be identified. Strategies dealing with the first step are directed towards the maximisation of effective population size and, therefore, act jointly on the reduction in the loss of genetic variation and in the increase of inbreeding. In this paper, the most relevant methods are summarised, including the so-called 'Optimum Contribution' methodology (contributions are proportional to the coancestry of each individual with the rest), which has been shown to be the best. Typically, this method is applied to pedigree information, but molecular marker data can be used to complete or replace the genealogy. When the population is subjected to explicit selection on any trait, the above methodology can be used by balancing the response to selection and the increase in coancestry/inbreeding. Different mating strategies also exist. Some of the mating schemes try to reduce the level of inbreeding in the short term by preventing mating between relatives. Others involve regular (circular) schemes that imply higher levels of inbreeding within populations in the short term, but demonstrate better performance in the long term. In addition, other tools such as cryopreservation and reproductive techniques aid in the management of small populations. In the future, genomic marker panels may replace the pedigree information in measuring the coancestry. The paper also includes the results of several experiments and field studies on the effectiveness and on the consequences of the use of the different strategies.

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Section: Managing the Contributions Of Individualsmentioning

confidence: 99%

Management of genetic diversity in small farm animal populations

Fernández

Meuwissen

Toro

et al. 2011

Animal

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“…Recently, Wu and Schaeffer [19] presented a study, where the methods of Grundy et al [5] and Verrier et al [16], which reduce inbreeding, were compared with their new method. All three methods selected for modified EBVs with an artificially reduced the effect of parent average on the animal model EBVs.…”

Section: Practical Schemesmentioning

confidence: 99%

Non-random mating for selection with restricted rates of inbreeding and overlapping generations

Sonesson¹,

Meuwissen²

2002

Genet. Sel. Evol.

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-Minimum coancestry mating with a maximum of one offspring per mating pair (MC1) is compared with random mating schemes for populations with overlapping generations. Optimum contribution selection is used, whereby ∆F is restricted. For schemes with ∆F restricted to 0.25% per year, 256 animals born per year and heritability of 0.25, genetic gain increased with 18% compared with random mating. The effect of MC1 on genetic gain decreased for larger schemes and schemes with a less stringent restriction on inbreeding. Breeding schemes hardly changed when omitting the iteration on the generation interval to find an optimum distribution of parents over age-classes, which saves computer time, but inbreeding and genetic merit fluctuated more before the schemes had reached a steady-state. When bulls were progeny tested, these progeny tested bulls were selected instead of the young bulls, which led to increased generation intervals, increased selection intensity of bulls and increased genetic gain (35% compared to a scheme without progeny testing for random mating). The effect of MC1 decreased for schemes with progeny testing. MC1 mating increased genetic gain from 11-18% for overlapping and 1-4% for discrete generations, when comparing schemes with similar genetic gain and size. mating / overlapping generations / selection / rate of inbreeding / genetic response / optimum contribution

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“…Both pieces of evidence suggest that the heritability estimates used in the EBV are too large. Use of a lower heritability estimate would reduce the range in EBV (Grundy et al 1994), but would have little effect on the ranking for selection. It would, however, reduce the estimates of genetic change in the population (Kennedy et al 1996), which were estimated by the trend in EBV through time (Sorenson and Kennedy 1984).…”

Section: Discussionmentioning

confidence: 99%

An empirical check on best linear unbiased prediction genetic evaluation using pig field recording data

Quinton¹,

Smith²

1997

Can. J. Anim. Sci.

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check on best linear unbiased prediction genetic evaluation using pig field recording data. Can. J. Anim. Sci. 77: 211-216. The theory and use of best linear unbiased prediction in genetic evaluation are well developed. However, there has been little empirical checking of its efficacy in practice. The objective here was to use a large body of Canadian pig performance records to check on the predicted benefits of BLUP in genetic evaluation. Phenotype records were available on fat depth and on days to 100 kg on some 65 000 progeny born in 1994 and 1995 from parents evaluated before 1994. Rank correlations between parent and progeny in data were calculated within herd-year-season to avoid effects due to differences in these factors. Computer simulation studies were also run to check on the predicted results. The simulation results confirmed the expectations on the higher correlation of mid-parental EBV than of mid-parental phenotype with progeny genotype and a regression (of progeny phenotype on mid-parental EBV) of unity when all relevant pedigree and performance data were used. In the data analysis, the (rank) correlations with progeny phenotype were consistently higher (36 and 27%) for mid-parental BLUP genetic evaluation than for mid-parental phenotypes, confirming the superiority of the BLUP evaluations over phenotypes. However, the regression of progeny phenotype on mid-parent BLUP EBV was usually less than the predicted value of unity. Simulation results suggest that either the base population heritability was lower than that used in the evaluation or that the information used was incomplete.Key words: Best linear unbiased prediction, EBV, pigs, performance, selection Quinton, V. M. et Smith, C. 1997. Vérification empirique de la méthode d'évaluation génétique BLUP à partir des relevés de production sur le terrain. Can. J. Anim. Sci. 77: 211-216. Bien que la théorie et l'utilisation de la méthode de BLUP soient toutes deux bien rodées, il n'y a eu que peu de vérifications empiriques de son efficacité sur le terrain. A partir des archives du Programme canadien de contrôle d'aptitudes, nous avons examiné les données phénotypiques relatives à l'épaisseur du lard dorsal et à l'âge des porcs au poids de marché (100 kg) recueillies sur quelque 65 000 porcs nés en 1994 et en 1995 de parents éval-ués avant 1994. Les corrélations de rang entre géniteurs et descendances étaient calculées par troupeau-année-saison de façon à éviter les effets imputables à des différences chez ces divers facteurs. Simultanément, des études en simulation sur ordinateur étaient conduites pour vérifier les résultats prédits. Les résultats de ces dernières études ont permis de confirmer les attentes en ce qui a trait aux plus fortes corrélations obtenues entre l'EBV, qu'entre le phénotype du parent moyen, et le phénotype de la descendance. Ils font également voir une régression proche de l'unité (génotype de la descendance sur EBV parent-moyen) lorsqu'on utilisait tous les relevés de généalogie et de performances pertinents. Dans l'analyse ...

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A note on using biased parameter values and non-random mating to reduce rates of inbreeding in selection programmes

Cited by 51 publications

References 11 publications

Management of genetic diversity in small farm animal populations

Management of genetic diversity in small farm animal populations

Non-random mating for selection with restricted rates of inbreeding and overlapping generations

An empirical check on best linear unbiased prediction genetic evaluation using pig field recording data

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