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Breeding Jersey cattle for Africa in the era of genomics

Breeding Jersey cattle for Africa in the era of genomics. Prof Norman Maiwashe 1,2 (PhD, Pri. Sci. Nat). 1 ARC-Animal Production Institute Private Bag X2 Irene 0062. 2 University of the Free State P.O . Box 339 Bloemfontein 9300.

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Breeding Jersey cattle for Africa in the era of genomics

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  1. Breeding Jersey cattle for Africa in the era of genomics Prof Norman Maiwashe1,2 (PhD, Pri. Sci. Nat) 1ARC-Animal Production Institute Private Bag X2 Irene 0062 2University of the Free State P.O. Box 339 Bloemfontein 9300 20th International WJCB Conference , Western Cape, South Africa, 17 Sept 2014

  2. Presentation Outline • A breeder’s dilemma • Inbreeding versus Genetic progress • How will genomics: • Complicateor Simplify breeding • Summary

  3. Genetic Improvement is a balancing act Minimal Inbreeding Rapid Genetic Progress

  4. The curse is in the principle! • Superior animals (sires) are provided more breeding opportunities While: • Inferior animals (sires) are denied breeding opportunities Consequently: • Most of the progeny are from few outstanding sires and are «likely to be outstanding themselves» • When this progeny in turn become parents, they are more «likely to mate with their siblings»

  5. Question 1: Is the rate of inbreeding reaching critical levels in Jersey populations?

  6. Inbreeding level in SA dairy cattle

  7. Inbreeding level in SA Jersey 4.8% Du Toit et al. (2012)

  8. Inbreeding in Canadian Jerseys Du Toit et al. (2012)

  9. Inbreeding depression • Inbreeding has a negative impact on longevity in SA Jersey cattle (Du Toit et al., 2012) A 1% increase in inbreeding is associated with ~0.5% reduction in longevity Lact. 1 Lact. 2 Lact. 3 Mean longevity -0.14% -0.22% -0.35%

  10. Inbreeding in the genomic era • ΔF will increase due to shorter rapid generation interval • Management of inbreeding will become more important • Opportunity • Genomics may allow for new ways to control inbreeding e.g. use of DNA to calculate genomic relatedness and inbreeding

  11. Answers to Question 1: • Inbreeding is real and should be managed • Use superior bulls that are less related to the population • Genomics could lead to rapid inbreeding • but offer better tools for managing inbreeding (genomic mating programs) • Remember: Inbreeding is not bad per se – it is rapid inbreeding that is bad • Mild inbreeding with intense selection is good

  12. Question 2: How was the Jersey breeder’s life before genomics?

  13. Genetic trend for Calving Interval

  14. Conformation and Udder Traits Figure: Genetic trends for « conformation » and « udder » in SA Jersey Theron et al. (2012)

  15. Answers to Question 2 How was the Jersey breeder’s life before genomics? Answer: • Good genetic progress made on measured traits (often with high h2) albeit at a relatively slow pace • Little progress on lowly heritable traits • Progress was costly (time and money)

  16. Question 3 How is the Jersey breeder’s life during genomics?

  17. Genomic opportunities • Genomics for managing deleterious haplotype carriers (e.g JH1, JH2 and Fertility 1) • Decreased reproductive efficiency (is accessible to the breeder) • Genomic selection (more about this later) • Selection of young animals with DNA test (with reasonable reliability ~60%) • Parentage verification or discovery of missing ancestors (is accessible to the breeder)

  18. Genomic selection • Requires a large number of animals with accurate proofs e.g. >1000 animals • Genotyping costs are still high • Use of cows in the reference population is a possibility • Genotyping a small group of animals with high density chips and using imputation • Important question: • Can I use genomic proofs from another country? • Answer: • Advise: tread carefully • Genomic proofs are population-specific and their reliabilities may erode in a different population • Using foreign scale could be hazardous for traits with low international genetic correlations (Partry and Ducrocq, 2014)

  19. Priorities during the Genomic Era • Genomic exploitation strategy: • High value animals (influential) • genotype with 50K or higher density SNP chip • Low value animals • genotyped using low density chips for: • Parentage verification • Genomic inbreeding • Deleterious haplotypes

  20. The KEY to genomic selection • Aggressive data collection (milk/performance recording) • What kind of data? • Fertility • Adaptation to heat stress • Weights / growth • Feed efficiency • Methane production • Health

  21. Answer to Question 3 How is the Jersey breeder’s life during genomics? Answer? • Genomics for parentage verification and managing deleterious haplotypes is a reality and beneficial • Genomics proofs presented on foreign scale should be treated cautiously

  22. Summary • Inbreeding is a threat to long-term genetic improvement and should be managed • Genomics presents an opportunity for fast-tracking genetic improvement • More emphasis should be placed on: • collection of data on traits that are difficult to improve through conventional selection • Both public and private (industry) investment is key to exploitation of genomics selection

  23. Thank You Dankievir u andaagNdi a livhuwa

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