1 / 23

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.

hamish-preston
Download Presentation

Breeding Jersey cattle for Africa in the era of genomics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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

More Related