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Breeding for scrapie resistance in France

Breeding for scrapie resistance in France. Isabelle Palhière 1 *, Brochard M. 5 , Astruc JM. 2 , Barillet F. 1 , Bed’Hom B. 3 , Bibé B. 1 , Bouix J. 1 , Catrou O. 4 , Dion F. 5 , Elsen JM. 1 , François D. 1 , Griffon L. 2 , Jullien E. 2 , Orlianges M. 5 , Perret G. 2 , Tribon P. 4.

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Breeding for scrapie resistance in France

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  1. Breeding for scrapie resistance in France Isabelle Palhière 1*, Brochard M.5, Astruc JM.2, Barillet F.1, Bed’Hom B.3, Bibé B.1, Bouix J.1, Catrou O.4, Dion F.5, Elsen JM.1, François D.1, Griffon L.2, Jullien E.2, Orlianges M.5, Perret G.2, Tribon P.4 1 INRA SAGA, Toulouse 2 Institut de l’Elevage 3 LABOGENA 4 Ministry of Agriculture 5 France UPRa Sélection

  2. The French scrapie eradication programme Four complementary actions • Clinical surveillance of the disease • Since 1996 • About 50 positive flocks per year • Active surveillance • 51,600 rapid tests • 150 positive animals

  3. The French scrapie eradication programme Four complementary actions • Scrapie eradication programme for affected flocks • Since 1996 • Based on genetic resistance since 2002 • Selection programme for scrapie resistance • Curative : help affected flocks to control scrapie • Preventive : Improve scrapie resistance in the whole population

  4. Selection programme for scrapie resistance General framework • Launched in all the sheep breeds • Based on : PrP gene polymorphism is linked to variability of scrapie susceptibility • Planned for 5 years(2002-2006) • Funded bythe Ministry of Agriculture • Ruled by a board including all the organisations of sheep production

  5. Included in existing breeding schemes Adapted to each breed French selection programme for scrapie resistance Implemented efficiently and rapidly

  6. Included in existing breeding schemes Adapted to each breed French selection programme for scrapie resistance Implemented efficiently and rapidly

  7. Pyramidal French selection organisation In sheep Selection flocks : 600,000 animals -Use of selection tools -Creation and diffusion of the genetic gain Commercial flocks : 9,000,000 animals Gene flow 620,000 AI 9,500 rams -Use of the genetic gain -Production of lambs, milk

  8. Concentration on selection flocks -Selection efficiency -Identification quality -Pedigree and production recording Breeding organisation Selection flock Selection flock Selection flock Selection flock Selection flock

  9. Laboratories Laboratories 10 laboratories approved -New analysis techniques -Genotyping capacity -Traceability Breeding organisation Selection flock Selection flock Selection flock Selection flock Selection flock

  10. Quality assurance and circulation of data -Include PrP data -Connect data bases Laboratories -Centralize data -Organise circulation Data base Breeding organisation Selection flock Selection flock Selection flock Selection flock Selection flock

  11. Management Laboratories Research Technical organisations -New abilities -Coordination research/ development Data base Breeding organisation Selection flock Selection flock Selection flock Selection flock Selection flock

  12. Included in existing breeding schemes Adapted to each breed French selection programme for scrapie resistance Implemented efficiently and rapidly

  13. Included in existing breeding schemes Adapted to each breed French selection programme for scrapie resistance Implemented efficiently and rapidly

  14. Four general objectives Eradicate the VRQ allele Selection flocks VRQ Affected flocks Commercial flocks

  15. Four general objectives Provide ARR/ARR rams or semen to affected flocks Selection flocks VRQ ARR/ARR ARR/ARR Affected flocks Commercial flocks

  16. Four general objectives Select for the ARR allele while maintaining genetic variability and selection for production traits Selection flocks VRQ ARR ARR/ARR ARR/ARR Affected flocks Commercial flocks

  17. Four general objectives Provide ARR/ARR rams or semen to commercial flocks Selection flocks VRQ ARR ARR/ARR ARR/ARR Affected flocks Commercial flocks

  18. Specific selection programmes… …adapted to each breed depending on : • Initial PrP allele frequencies

  19. Initial PrP allele frequencies in the French breeds

  20. Specific selection programmes… …adapted to each breed depending on : • Initial PrP allele frequencies • Scrapie prevalence in the breed • Characteristics of the breeding scheme : • Selection objectives • Use of breeding tools : example of the AI rate

  21. Breed AI rate (%)

  22. Specific selection programmes… …adapted to each breed depending on : • Initial PrP allele frequencies • Scrapie prevalence in the breed • Characteristics of the breeding scheme • Weight of the breeding scheme in the whole population

  23. Weigth of the breeding schemes in the whole population Importance of the gene flow Size of the selection nucleus

  24. Type of genotyped animals Assortative matings X Elite rams Sire dams Gathering structures AI or young males for commercial flocks Priority to the males

  25. Type of genotyped animals Priority to the males Assortative matings X Elite rams Sire dams Genotyping Gathering structures AI or young males for commercial flocks

  26. Type of genotyped animals Increase the candidates number Genotype as sooner as possible Assortative matings X Elite rams Sire dams Genotyping Gathering structures AI or young males for commercial flocks

  27. Type of genotyped animals Ratio of genotyped animals 100% 430% / year 19% 34% / year 2002 2003 Adult sires 10,000 0 Young rams 28,600 40,900 Sire dams 15,500 7,700 Ewe lambs 29,100 41,300 TOTAL 83,200 89,900

  28. Importance of genotyping depending on the breeding schemes (2003) % Breed

  29. Included in existing breeding schemes Adapted to each breed French selection programme for scrapie resistance Implemented efficiently and rapidly

  30. Included in existing breeding schemes Adapted to each breed French selection programme for scrapie resistance Implemented efficiently and rapidly

  31. All the French sheep breeds involved • 30 breeds (+ 20 rare breeds) • 2,100 flocks • 600,000 ewes / 14,000 rams

  32. Evolution of PrP frequencies Young sires 2002 Young sires 2003 Example of terminal sires breeds 100% 90% 80% 70% VRQ/X 60% ARQ/ARQ 50% ARR/ARQ 40% ARR/ARR 30% 20% 10% 0% Adult sires

  33. Evolution of PrP frequencies ARR frequency of young males after two years of selection % ARR frequency Breed

  34. Evolution of ARR frequency, genetic level and diversity Example of the Lacaune dairy breed Total merit index (std) % ARR / No grand-sires

  35. Conclusion • Selection on the PrP gene : efficient strategy to improve scrapie resistance • French selection programme since 2002 • 2 aims : • help the affected flocks to control scrapie • improve scrapie resistance in the whole population • 2 main characteristics : • Included in existing breeding schemes • Adapted to each breed • After 2 years, for the young sires : • Elimination of the VRQ allele • Rapid evolution of ARR allele frequency

  36. Thank you for your attention

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