A definition of unknown parent groups based on bull usage patterns across herds

In genetic evaluations, the definition of unknown parent groups (UPG) is usually based on time periods, selection path and flows of foreign founders. The definition of UPG may be more complex for populations presenting genetic heterogeneity due to both, large national expansion and coexistence of ar...

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Main Authors: A. Bouquet, G. Renand, F. Phocas
Format: Article
Language:English
Published: Elsevier 2011-01-01
Series:Animal
Subjects:
Online Access:http://www.sciencedirect.com/science/article/pii/S1751731110002144
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author A. Bouquet
G. Renand
F. Phocas
author_facet A. Bouquet
G. Renand
F. Phocas
author_sort A. Bouquet
collection DOAJ
description In genetic evaluations, the definition of unknown parent groups (UPG) is usually based on time periods, selection path and flows of foreign founders. The definition of UPG may be more complex for populations presenting genetic heterogeneity due to both, large national expansion and coexistence of artificial insemination (AI) and natural service (NS). A UPG definition method accounting for beef bull flows was proposed and applied to the French Charolais cattle population. It assumed that, at a given time period, unknown parents belonged to the same UPG when their progeny were bred in herds that used bulls with similar origins (birth region and reproduction way). Thus, the birth period, region and AI rate of a herd were pointed out to be the three criteria reflecting genetic disparities at the national level in a beef cattle population. To deal with regional genetic disparities, 14 regions were identified using a factorial approach combining principal component analysis and Ward clustering. The selection nucleus of the French cattle population was dispersed over three main breeding areas. Flows of NS bulls were mainly carried out within each breeding area. On the contrary, the use and the selection of AI bulls were based on a national pool of candidates. Within a time period, herds of different regions were clustered together when they used bulls coming from the same origin and with an estimated difference of genetic level lower than 20% of genetic standard deviation (σg) for calf muscle and skeleton scores (SS) at weaning. This led to the definition of 16 UPG of sires, which were validated as robust and relevant in a sire model, meaning numerically stable and corresponding to distinct genetic subpopulations. The UPG genetic levels were estimated for muscle and SS under sire and animal models. Whatever the trait, differences between bull UPG estimates within a time period could reach 0.5 σg across regions. For a given time period, bull UPG estimates for muscle and SS were generally larger by 0.30 to 0.75 σg than those of cows. Including genetic groups in the evaluation model increased the estimated genetic trends by 20% to 30%. It also provoked re-ranking in favor of bulls and cows without pedigree.
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spelling doaj.art-f437281249f44463b6188150ff79e9af2022-12-21T19:54:30ZengElsevierAnimal1751-73112011-01-0153337346A definition of unknown parent groups based on bull usage patterns across herdsA. Bouquet0G. Renand1F. Phocas2INRA, UMR1313 Génétique Animale et Biologie Intégrative, F-78352 Jouy-en-Josas, France; AgroParisTech, UMR1313 Génétique Animale et Biologie Intégrative, F-75231 Paris Cedex 05, FranceINRA, UMR1313 Génétique Animale et Biologie Intégrative, F-78352 Jouy-en-Josas, FranceINRA, UMR1313 Génétique Animale et Biologie Intégrative, F-78352 Jouy-en-Josas, FranceIn genetic evaluations, the definition of unknown parent groups (UPG) is usually based on time periods, selection path and flows of foreign founders. The definition of UPG may be more complex for populations presenting genetic heterogeneity due to both, large national expansion and coexistence of artificial insemination (AI) and natural service (NS). A UPG definition method accounting for beef bull flows was proposed and applied to the French Charolais cattle population. It assumed that, at a given time period, unknown parents belonged to the same UPG when their progeny were bred in herds that used bulls with similar origins (birth region and reproduction way). Thus, the birth period, region and AI rate of a herd were pointed out to be the three criteria reflecting genetic disparities at the national level in a beef cattle population. To deal with regional genetic disparities, 14 regions were identified using a factorial approach combining principal component analysis and Ward clustering. The selection nucleus of the French cattle population was dispersed over three main breeding areas. Flows of NS bulls were mainly carried out within each breeding area. On the contrary, the use and the selection of AI bulls were based on a national pool of candidates. Within a time period, herds of different regions were clustered together when they used bulls coming from the same origin and with an estimated difference of genetic level lower than 20% of genetic standard deviation (σg) for calf muscle and skeleton scores (SS) at weaning. This led to the definition of 16 UPG of sires, which were validated as robust and relevant in a sire model, meaning numerically stable and corresponding to distinct genetic subpopulations. The UPG genetic levels were estimated for muscle and SS under sire and animal models. Whatever the trait, differences between bull UPG estimates within a time period could reach 0.5 σg across regions. For a given time period, bull UPG estimates for muscle and SS were generally larger by 0.30 to 0.75 σg than those of cows. Including genetic groups in the evaluation model increased the estimated genetic trends by 20% to 30%. It also provoked re-ranking in favor of bulls and cows without pedigree.http://www.sciencedirect.com/science/article/pii/S1751731110002144beef cattleunknown parentsgenetic evaluationgenetic groupsgenetic trend
spellingShingle A. Bouquet
G. Renand
F. Phocas
A definition of unknown parent groups based on bull usage patterns across herds
Animal
beef cattle
unknown parents
genetic evaluation
genetic groups
genetic trend
title A definition of unknown parent groups based on bull usage patterns across herds
title_full A definition of unknown parent groups based on bull usage patterns across herds
title_fullStr A definition of unknown parent groups based on bull usage patterns across herds
title_full_unstemmed A definition of unknown parent groups based on bull usage patterns across herds
title_short A definition of unknown parent groups based on bull usage patterns across herds
title_sort definition of unknown parent groups based on bull usage patterns across herds
topic beef cattle
unknown parents
genetic evaluation
genetic groups
genetic trend
url http://www.sciencedirect.com/science/article/pii/S1751731110002144
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