The Booroola gene in Mérinos d'Arles sheep : introgression of the FecB gene & productivity of FecB heterozygous carrier ewes under farm conditions J. Teyssier.

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

1INRA-Agro.M Elevage des Ruminants en Régions Chaudes, Montpellier, France2INRA Station d’Amélioration Génétique des Animaux, Castanet-Tolosan, France3Agro.M, Domaine du Merle, Salon de Provence, France4INRA, Laboratoire de Génétique Cellulaire, Castanet-Tolosan, France

IWMGQSG(Toulouse, 8-11 Dec 2003)

• 1982 :1982 : transfer of 5 Booroola rams from Australia

introgression of the FecB gene in a Mérinos d'Arles flock (Domaine du Merle) backcrossing process through males and

females genotyping at each generation for females and a part of the males (Elsen et Le Roy, 1991)

1/2 MA 3/4 MA 7/8 MA 15/16 MA

FecB B /FecB + 2,93 2,23 2,08 2,07

(n=137) (n=269) (n=510) (n=849)

FecB + /FecB + 1,21 1,09 1,07 1,04

(n=135) (n=592) (n=1078) (n=991)

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

0

4

8

12

16

20

1/2 MA 3/4 MA 7/8 MA 15/16 MA

No

n o

vula

tio

n r

eco

rds

(%

)

FecBB/FecB+ FecB+/FecB+

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)

Greater sexual precocity of carrier ewes

comparison of FecB heterozygous carrier and non-carrier MA eweshigh percentage background breed (at least 7/8 MA)pastoral breeding system of the MA breed in south-eastern France

Evaluations of the productivity of FecB carrier Mérinos d'Arles ewes

Exp. 1 : 1993-1995 (3 years)1993-1995 (3 years)experimental farm (Domaine du

Merle) Exp. 2 : since 199since 19999

private farm (Mr and Mrs D. Raymond)

Exp. 1 : Domaine du Merle

Comparison of 4 genotypes : FecBB/FecB+ MA*

FecB+/FecB+ MA*Pure breed MAF1 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

(FecB B / (FecB + /FecB + ) FecB + )

OR (first oestrus) + 1.2 ovulations/ ewe 2.59 1.38

Litter size at birth + 0.9 lamb born/ ewe lambing 2.10 1.21Litter size at 70 d* + 0.6 lamb/ ewe lambing 1.72 1.14

Lamb BW at 70 d (kg) - 1.8 kg (- 9%) 18.8 20.6

Weight of 70-d lamb (kg) + 8,6 kg (+ 40%) 29.5 20.9/ ewe joined

* 70 days (by weaning) (Teyssier et al., 1998)

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 :Overall prolificacy : FecBB/FecB+ 1.86 (+ 0.75)

FecB+/FecB+ 1.11

(1.59 and 1.15 on the first mating, respectively)

• Production of lambsProduction 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

Exp. 1 Exp. 2

Overall prolificacy of carriers 2,10 1,86

Proportion (%) of LS > 3 29,5 14,5

Artificial rearing of lambs (%) 34 7*

Lamb mortality before weaning (%) 18,4 14,9

* fostering + artificial rearing of lambs

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).

AcknowledgementsAcknowledgements

Thanks to the staff of the "DomaineThanks to the staff of the "Domaine du Merle"du Merle" ((C. Maton, J.D. Guyonneau, D. MontierC. Maton, J.D. Guyonneau, D. Montier) for the ) for the management management of sheep andof sheep and the data collection. the data collection.

to to J. RallièresJ. Rallières of the INRA LGC for of the INRA LGC for the genotyping of animals, the genotyping of animals,

to to Mr and Mrs RaymondMr and Mrs Raymond, breeders in the , breeders in the Lubéron, for Lubéron, for thetheir contribution to these results.ir contribution to these results.

A part of this work was supported by the A part of this work was supported by the EC program CT92-0232EC program CT92-0232

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