The Booroola gene in Mérinos d'Arles sheep : IWMGQSG (Toulouse, 8-11 Dec 2003) The Booroola gene in Mérinos d'Arles sheep : introgression of the FecB gene & productivity of FecB heterozygous carrier ewes under farm conditions J. Teyssier1, J.M. Elsen2, L. Bodin2, P.M. Bouquet3, P. Mulsant4 and J. Thimonier1 J’ai remplacé introduction par introgression 1INRA-Agro.M Elevage des Ruminants en Régions Chaudes, Montpellier, France 2INRA Station d’Amélioration Génétique des Animaux, Castanet-Tolosan, France 3Agro.M, Domaine du Merle, Salon de Provence, France 4INRA, Laboratoire de Génétique Cellulaire, Castanet-Tolosan, France

1982 : transfer of 5 Booroola rams from Australia introgression of the FecB gene in a Mérinos d'Arles flock (Domaine du Merle) Genotyping Importation = transfert backcrossing process through males and females genotyping at each generation for females and a part of the males (Elsen et Le Roy, 1991)

Mean ovulation rate of 1-yr-old ewes in the MA backcross generations (No. of ovulation records) (Data collected from 1984 to 1994 on three consecutive cycles between October and mid-December) Specificity of early stages of introgression

Percentage of endoscopies without any observation of CL in 1-yr-old ewes of the successive backcross generations (Data collected from 1984 to 1994 on three consecutive cycles between October and mid-December) FecBB/FecB+ FecB+/FecB+ 20 16 12 Non ovulation records (%) 8 4 1/2 MA 3/4 MA 7/8 MA 15/16 MA Greater sexual precocity of carrier ewes

Evaluations of the productivity of FecB carrier Mérinos d'Arles ewes comparison of FecB heterozygous carrier and non-carrier MA ewes high percentage background breed (at least 7/8 MA) pastoral breeding system of the MA breed in south-eastern France Exp. 1 : 1993-1995 (3 years) experimental farm (Domaine du Merle) Exp. 2 : since 1999 private farm (Mr and Mrs D. Raymond)

* ewes were genotyped on OR observed when 1-yr-old Exp. 1 : Domaine du Merle Comparison of 4 genotypes : FecBB/FecB+ MA* FecB+/FecB+ MA* Pure breed MA F1 Romanov x MA * ewes were genotyped on OR observed when 1-yr-old during 3 years (1993, 1994, 1995) on a total of 1.222 mating records (602 ewes) Natural mating in spring after a "ram effect" with harnessed Ile-de-France rams (OR on the first mating) First mating at 18 mo of age

Exp. 1. Changes in productivity of FecB carrier MA compared with non-carrier MA ewes (Teyssier et al., 1998)

* ewe-lambs were genotyped using genetic markers Exp. 2 : Private farm (D. Raymond) Comparison of 2 genotypes : FecBB/FecB+ MA* FecB+/FecB+ MA* * ewe-lambs were genotyped using genetic markers since 1999 on 25 carrier and 17 non-carrier ewes born in October 1998 Natural mating in spring (main mating period) and in autumn with MA rams First mating at 12 mo of age (autumn 1999)

Exp. 2. Comparison of productive careers of FecB carrier and non-carrier MA ewes from 1999 to 2003 Overall prolificacy : FecBB/FecB+ 1.86 (+ 0.75) FecB+/FecB+ 1.11 (1.59 and 1.15 on the first mating, respectively) Production of lambs* : FecBB/FecB+ 5.2 lambs/ ewe (+ 67%) FecB+/FecB+ 3.1 " " * Total number of lambs weaned/ ewe over the studied interval Greater ability of carrier ewes for early recycling on an autumn lambing

Consequences of increase in prolificacy in FecB carrier MA on components of lamb production

CONCLUSIONS Results from the first trial in a private farm (Exp. 2) shows that the FecB gene could be introduced in a larger part of the flock without major change in its extensive management, except for the organisation of mating. Under similar breeding systems, the consequent decrease in prolificacy of the carrier ewes in Exp. 2 might result from the difference between both experiments in the genotype determination (selection on higher OR in Exp. 1).

Acknowledgements Thanks to the staff of the "Domaine du Merle" (C. Maton, J.D. Guyonneau, D. Montier) for the management of sheep and the data collection. to J. Rallières of the INRA LGC for the genotyping of animals, to Mr and Mrs Raymond, breeders in the Lubéron, for their contribution to these results. A part of this work was supported by the EC program CT92-0232

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