Genet. Sel. Evol.
Volume 35, Number 6, November-December 2003
|Page(s)||637 - 655|
Genetic variability of six French meat sheep breeds in relation to their genetic managementMarie Hubya, Laurent Griffona, Sophie Moureauxa, b, Hubert De Rochambeauc, Coralie Danchin-Burgea and Étienne Verrierd
a Institut de l'Élevage, Département de génétique, 149 rue de Bercy, 75495 Paris Cedex 12, France
b Station de génétique quantitative et appliquée, Institut national de la recherche agronomique, 78352 Jouy-en-Josas Cedex, France
c Station d'amélioration génétique des animaux, Institut national de la recherche agronomique, BP 27, 31326 Castanet-Tolosan Cedex, France
d UMR Génétique et diversité animales, Institut national de la recherche agronomique, Institut national agronomique Paris-Grignon, 16 rue Claude Bernard, 75231 Paris Cedex 05, France
(Received 18 November 2002; accepted 16 June 2003)
Some demographic parameters, the genetic structure and the evolution of the genetic variability of six French meat sheep breeds were analysed in relation with their management. Four of these breeds are submitted to more or less intense selection: the Berrichon du Cher (BCH), Blanc du Massif Central (BMC), Charollais (CHA) and Limousin (LIM); the other two breeds are under conservation: the Roussin de La Hague (RLH) and Solognot (SOL). Genealogical data of the recorded animals born from 1970 to 2000 and of their known ancestors were used. The most balanced contributions of the different flocks to the sire-daughter path was found in the SOL. In the BCH, a single flock provided 43% of the sire-AI sire path, whereas the contributions of the flocks were more balanced in the BMC and LIM (the only other breeds where AI is used to a substantial amount). The distribution of the expected genetic contribution of the founder animals was found to be unbalanced, especially in the BCH and LIM. The effective numbers of ancestors (founders or not) for the ewes born from 1996 to 2000 were equal to 35 (BCH), 144 (BMC), 112 (CHA), 69 (LIM), 40 (RLH) and 49 (SOL). Inbreeding was not analysed in the BMC, due to incomplete pedigree information. From 1980 on, the rates of inbreeding, in percentage points per year, were +0.112 (BCH), +0.045 (CHA), +0.036 (LIM), +0.098 (RLH) and +0.062 (SOL). The implications of the observed trends on genetic variability are discussed in relation to the genetic management of each breed. The need for a larger selection basis in the BCH, the efficiency of the rules applied in the SOL to preserve the genetic variability and the need for a more collective organisation in the CHA and RLH are outlined.
Key words: genetic variability / inbreeding / selection schemes / conservation programmes / sheep
Correspondence and reprints: Étienne Verrier email@example.com
© INRA, EDP Sciences 2003