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Genetic variation of the reference population for quantitative trait loci research in South African Angora goats

Published online by Cambridge University Press:  20 November 2009

C. Visser  and
E. van Marle-Koster
C. Visser*
Affiliation:
Department of Animal and Wildlife Sciences, University of Pretoria, Pretoria 0002, South Africa
E. van Marle-Koster
Affiliation:
Department of Animal and Wildlife Sciences, University of Pretoria, Pretoria 0002, South Africa
*
Correspondence to: C. Visser, Department of Animal and Wildlife Sciences, University of Pretoria, Pretoria 0002, South Africa. email: carina.visser@up.ac.za
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Summary

The South African Angora goat industry makes the largest contribution to global mohair production. Mohair is a luxury fibre and production of a high quality clip is essential. For many years genetic improvement of Angoras in South Africa was based on quantitative selection. Genome mapping efforts provided new avenues for improvement and a quantitative trait loci (QTL) study was initiated to identify QTL associated with mohair traits. The aim of this study was to describe the genetic diversity of the reference population using the available stud and commercial herds with full phenotypic records. The most appropriate QTL design was identified based on the population structure with regard to the families and number of bucks available for breeding. Four herds, consisting of 1067 pure bred goats in 12 half-sib families, were included. Blood samples were obtained from the herds, 94 markers were tested and diversity parameters were estimated. The average number of alleles per marker varied between 5.4 and 7.2 amongst the herds, whereas the observed heterozygosity varied between 0.59 and 0.67. The genetic structure of these herds was found appropriate for use as a reference population as they showed sufficient genetic variability.

Résumé

L'industrie de la chèvre angora de l'Afrique du Sud apporte la plus grande contribution à la production mondiale de mohair. Le mohair est une fibre de luxe et la production d'une tonte de haute qualité est essentielle. Pendant de nombreuses années, l'amélioration génétique des chèvres angoras en Afrique du Sud était basée sur la sélection quantitative. Les activités de cartographie des génomes ont fourni de nouvelles voies pour l'amélioration et une étude sur le QTL a été lancée pour identifier le locus à effets quantitatifs associé aux caractères du mohair. Le but de cette étude était de décrire la diversité génétique de la population de référence en utilisant les troupeaux reproducteurs et commerciaux disponibles ayant des contrôles phénotypiques complets. Le plan de QTL le plus approprié a été identifié sur la base de la structure de la population considérant les familles et le nombre de boucs disponibles pour la sélection. Quatre troupeaux de 1067 chèvres de race pure dans 12 familles à descendance uniparentale ont été inclus. On a effectué des prises de sang sur les animaux des troupeaux, on a testé 94 marqueurs et estimé les paramètres de la diversité. Le nombre moyen d'allèles par marqueur variait entre 5,4 et 7,2 dans les troupeaux, tandis que l'hétérozygosité variait entre 0,59 et 0,67. La structure génétique de ces troupeaux a été considérée adéquate pour son utilisation en tant que population de référence car les troupeaux ont montré une variabilité génétique suffisante.

Resumen

La industria de la cabra Angora de Sudáfrica es la que representa el mayor porcentaje de producción de mohair a nivel mundial. El Mohair es una fibra considerada de lujo, y la producción donde se lleve a cabo una esquila de alta calidad es esencial. Durante muchos años la mejora genética de cabras Angora en Sudáfrica ha estado basada en la selección cuantitativa. Los esfuerzos llevados a cabo en relación con el mapeo genético abrieron nuevos caminos para mejorar, y se inició un estudio QTL para identificar el QTL asociado con los rasgos de mohair. El propósito de dicho estudio consistió en describir la diversidad genética de la población de referencia utilizando el semental disponible y rebaños comerciales con registros fenotípicos completos. El diseño más apropiado de QTL fue identificado en base a la estructura poblacional con respecto a las familias y al número de machos disponibles para la cría. Se incluyeron cuatro rebaños que sumaban 1067 cabras de raza pura en 12 familias de medios hermanos. Se obtuvieron muestras de sangre de los rebaños, se probaron 94 marcadores, y se estimaron parámetros de diversidad. El número promedio de alelos por marcador varió entre 5.4 y 7.2 entre los rebaños, mientras que la heterocigosidad observada varió entre 0.59 y 0.67. La estructura genética de estos rebaños se consideró apropiada para ser utilizada como población de referencia, dado que mostraba suficiente variabilidad genética.

Keywords

Angora goatsmohairgenetic variationquantitative trait loci designchèvres Angoramohairvariation génétiqueschéma des locis à effets quantitatifsAngoramohairvariabilidad genéticaloci de rasgos cuantitativos
Type
Research Article
Information
Animal Genetic Resources/Resources génétiques animales/Recursos genéticos animales , Volume 45 , October 2009 , pp. 113 - 119
Copyright
Copyright © Food and Agriculture Organization of the United Nations 2009

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