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Miniature Bull Terriers: Breeding Strategies for Health Dr Sarah Blott

Miniature Bull Terriers: Breeding Strategies for Health Dr Sarah Blott. Animal Health Trust The science behind animal welfare. TOOLS to aid breeding decisions. BREEDING PROGRAMMES for long-term health. General health Management of genetic diversity Optimised breeding programmes

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Miniature Bull Terriers: Breeding Strategies for Health Dr Sarah Blott

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  1. Miniature Bull Terriers: Breeding Strategies for Health Dr Sarah Blott Animal Health Trust The science behind animal welfare

  2. TOOLS to aid breeding decisions BREEDING PROGRAMMES for long-term health General health Management of genetic diversity Optimised breeding programmes Reduce or eradicate known disease and maintain long-term health Single gene diseases DNA tests Complex diseases Estimated Breeding Values (EBVs) Genomic BVs (based on DNA) Mate selection program

  3. Overview • Gene pool and genetic diversity • Inbreeding • Approaches to minimising diversity loss • Current situation in the MBT • Future breeding strategies

  4. Gene pool and genetic diversity

  5. Gene pool and genetic diversity

  6. Inbreeding Coancestry/kinship Inbreeding coefficient

  7. Inbreeding coefficient 1/2 1/2 1/2 1/2 1/2 1/2 (1/2)6 = 0.0156

  8. Genetic bottlenecks

  9. Diversity loss • High risk factor for emergence of new inherited disease • Long-term health means managing the loss of diversity • Controlling the rate of increase of inbreeding

  10. Control of inbreeding • What is the end goal? • Constrain rate of inbreeding (ΔF) to no more than 0.5% per generation • Effective population size (Ne)= 100 At least! • If below this, fitness of the population will steadily decrease and population will become unviable in the long-term

  11. Possible approaches • Minimising coancestry (kinship) of matings • Increasing numbers of animals used for breeding • Equalising the use of males and females • Optimising genetic contributions • Inter-breeding

  12. Miniature Bull Terrier

  13. Number of KC registrations 4,110 dogs 354 sires 797 dams

  14. Number of sires and dams used Mean no. sires = 18.7 Mean no. dams = 33.2 Ratio = 1.72 dams/sire

  15. Ratio of dams/sires 1981 1993

  16. Percentage dogs used for breeding 15% males become sires 40% females become dams

  17. Observed and expected inbreeding

  18. Effective population size (Ne) % per generationNeRegistered/year MBT 1.1 48 203 IRWS 1.8 28 133 CKCS 0.4 123 11,903 Labrador 0.5 103 26,757

  19. Number of offspring per sire/dam Dams Mean no. offspring = 5.6 Sires Mean no. offspring = 13.7 4 sires > 100 offspring 15 dams > 20 offspring

  20. Population relationships MBT born between 2006-2008

  21. Conclusions • scope for improvement • minimising coancestry (kinship) of matings • optimum contributions (no. of offspring)

  22. PLL • approx. 1200 dogs of breeding age in UK • genotype all possible dogs and re-select breeding individuals? • breed with carriers for one further generation and select unaffected homozygote (normal) replacements • further analysis based on pedigree and genotyping results

  23. http://www.the-kennel-club.org.uk/services/public/health/search/Default.aspxhttp://www.the-kennel-club.org.uk/services/public/health/search/Default.aspx Inbreeding coefficient Kinship coefficients Recommended Ballymore Delight 0.02 Ballymore Samson 0.01 Legend of Kilkenny 0.02 Rosedawn Diamond 0.12 Lordswood Romancer 0.08 Rosedawn Delilah 0.04

  24. Acknowledgements • Dr Tom Lewis (KCGC at the AHT) • Dr Jeff Sampson (The Kennel Club)

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