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Genetic correlations between the performance of purebred and crossbred pigs

Genetic correlations between the performance of purebred and crossbred pigs. Sansak Nakavisut Dr.Ron Crump Matias Suarez Dr.Hans Graser. Introduction. Nucleus herds test & select purebreds But the end products are crossbreds (multipliers and commercial herds)

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Genetic correlations between the performance of purebred and crossbred pigs

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  1. Genetic correlationsbetween the performance ofpurebredandcrossbredpigs Sansak Nakavisut Dr.Ron Crump Matias Suarez Dr.Hans Graser

  2. Introduction • Nucleus herds test & select purebreds • But the end products are crossbreds (multipliers and commercial herds) • This assumes rg between purebreds and crossbreds of “1” • If not “1”, testing and genetic evaluation procedure may need some changes

  3. In general • Estimation of rg between purebreds and crossbreds NOT possible or NOT reliable • Performance test records on crossbreds not available • Crossbred records may be available BUT from different environments (nucleus VS multiplier herds)

  4. Thai government pig breeding farms • Crossbreds were performance tested • Purebreds and crossbreds were produced in the same conditions (environments, herds, management, feeding..) • Litter records available from both crossbred and purebred sows • Allows reliable estimation of rg between pure- and crossbreds

  5. Objectives • To estimate genetic correlations (rg)between the performance of purebreds and crossbreds • To validate the conventional genetic evaluation procedure (whether rg = 1)

  6. DU LW LR LRxLW LWxLR DUx(LRxLW) DUx(LWxLR) Breeding diagram GGP GP PS

  7. Performance test records by breeds

  8. Litter records by breeds

  9. PRODUCTION TDG ADG FCR BF Body Length REPRODUCTION NPB NBA LS3W LWB LW3W GEST Traits to be analysed

  10. Statistical model for test records assumption

  11. Statistical model for litter records assumption

  12. Fixed effect model for test records

  13. Bribreed fHYSjfarrowing herd-year-season AgeCkage class of the farrowing sow Parlparity of litter LitBrm(Bri)nested litter-breed within breed of sow Fixed effect model for litter records The same fixed effects were fitted for all litter traits

  14. Results: rg (pure&cross)

  15. Discussion (production traits) • rg (pure&cross) high enough => testing and selecting of purebreds in the nucleus can genetically improve the production traits of crossbreds in multiplier and commercial herds • To reduce cost of unnecessary test of crossbreds • Conventional testing of purebreds is validated

  16. Discussion (reproduction traits) • rg (pure&cross) NOT “1” (although positive) => selecting on purebred litter records can genetically improve the reproduction of crossbred sows BUT not as efficient as incorporating crossbred records in the genetic evaluation procedure. • Crossbred records readily available in most multipliers with no extra cost => combine them with purebred records to produce EBVs for litter traits

  17. Conclusion • Genetic correlations between pure- and crossbreds for production traits are high • Therefore, conventional testing and selecting of purebreds is validated by this study

  18. Conclusion • Genetic correlations between pure- and crossbreds for reproduction traits are low to moderate • Therefore, we must include crossbred information into the genetic evaluation procedure to improve reproduction traits of crossbred sows

  19. ThanksDept. Livestock Development (DLD)ThailandUNERS / IPRSAGBU UNE

  20. Genetic links b/w cross & purebreds 51 common grandparents (21 grandsires & 30 grandams) 481 Crossbred litters (38%) (Total = 1265) 544 Purebred litters (5%) (Total = 10558) Litter records

  21. Methods and Models • Treat pure- and crossbred records as different traits eg. ADGp and ADGc • Bivariate analysis of the two separate traits using ASReml; animal model • Estimate additive genetic covariances and genetic correlations between the two traits

  22. Material and methods • DU, LW, LR & their crosses • 11-year (1993-2003) • 9075 performance test records • 11823 litter records (from 3908 sows)

  23. Number of breeds per contemporary group (HYS) Test records Litter records Frequency (%) Frequency (%) Breeds/CG (fHYS) Breeds/CG (tHYS)

  24. Genetic links b/w cross & purebreds 80 common parents (39 sires & 41 dams) 429 Crossbred records (30%) (Total = 1409) 415 Purebred records (5%) (Total = 7666) Performance test records

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