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Genetic variability of the Norwegian Fjord horse in North America

Published online by Cambridge University Press:  19 August 2011

A.S. Bhatnagar
Affiliation:
Department of Animal and Poultry Sciences, Litton-Reaves Hall, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
C.M. East
Affiliation:
Department of Animal and Poultry Sciences, Litton-Reaves Hall, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
R.K. Splan*
Affiliation:
Department of Animal and Poultry Sciences, Litton-Reaves Hall, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
*
Correspondence to: R.K. Splan, 5527 Sullivans Mill Road, Middleburg, VA 20117, USA. email: [email protected]
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Summary

Pedigrees of a reference population of 1 659 North American Norwegian Fjord horses were traced to founders and analysed for coefficients of inbreeding and genetic variability. Effective population size was 207.8 and there were 641 total founders. Pedigree completeness was close to 100 percent for 6 generations, with 9.8 average complete generation equivalents. The average inbreeding coefficient was 3.2 percent for the entire pedigree and 1.6 percent for pedigrees traced back five generations. Average inbreeding coefficients by year of birth increased until 1983, before decreasing and then stabilizing through 2009. Effective number of founders, ancestors and genomes were 96, 30.0 and 12.7, respectively. Low effective number of founders and ancestors indicate that genetic diversity has been lost in the development of the breed in North America. However, registry-enforced breeding strategies have contributed to lower inbreeding coefficients in the current generation.

Résumé

Les arbres généalogiques d'une population de référence constituée de 1 659 chevaux Fjord norvégiens de l'Amérique du Nord ont été déterminés et analysés pour ce qui concerne la consanguinité et la variabilité génétique. La taille réelle de la population est de 207,8 animaux et les fondateurs sont au total 641. La généalogie est résultée exhaustive presque à 100 pour cent pour 6 générations, avec une moyenne de 9,8 équivalents de génération complète. Le coefficient moyen de consanguinité est de 3,2 pour cent pour l'arbre généalogique entier et de 1,6 pour cent pour la généalogie remontant à 5 générations. Les coefficients moyens de consanguinité par année de naissance ont augmenté jusqu'en 1983, avant de diminuer et ensuite de se stabiliser jusqu'à fin 2009. Les nombres réels des fondateurs, des ancêtres et des génomes sont respectivement 96, 30 et 12,7. Le faible nombre réel de fondateurs et d'ancêtres indique une perte de diversité génétique lors de la mise en valeur de la race en Amérique du Nord. Toutefois, les stratégies de sélection imposées par le registre ont contribué à faire baisser les coefficients de consanguinité dans la génération courante.

Resumen

Se han examinado los pedigríes y analizado los coeficientes de consanguinidad y la variabilidad genética de una población de referencia de 1 659 individuos de la raza equina de los Fiordos de Noruega, existentes América del Norte. El tamaño efectivo de la población fue 207,8, con 641 fundadores totales. El pedigrí estaba completo, casi al 100 percent, en las 6 primeras generaciones, con 9,8 equivalentes de la generación media completa. El coeficiente de consanguinidad fue del 3,2 percent para todo el pedigrí y de 1,6 percent teniendo en cuenta sólo las 5 primeras generaciones del pedigrí. Los coeficientes de consanguinidad medios se incrementaron por año de nacimiento hasta 1983, antes de disminuir y luego estabilizarse en 2009. El número efectivo de fundadores, ancestros y genomas fue de 96, 30, y 12,7, respectivamente. El bajo número efectivo de fundadores y ancestros indican que la diversidad genética se ha perdido con el desarrollo de la raza en América del Norte. Sin embargo, los registros obligatorios como parte de las estrategias de mejora han contribuido a reducir los coeficientes de consanguinidad en la generación actual.

Type
Research Article
Copyright
Copyright © Food and Agriculture Organization of the United Nations 2011

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