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Bell Ranch: Integrated Seedstock and Commercial Programs

Bell Ranch: Integrated Seedstock and Commercial Programs. Genetics . Mule Camp produces 40 bulls each year for the commercial enterprise. Weaning. Selection is for the weaning weight of the calves  205 days of age. Question.

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Bell Ranch: Integrated Seedstock and Commercial Programs

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  1. Bell Ranch: Integrated Seedstock and Commercial Programs Genetics Mule Camp produces 40 bulls each year for the commercial enterprise.

  2. Weaning Selection is for the weaning weight of the calves  205 days of age

  3. Question If we select for weaning weight and increase the growth potential of our cattle: What will happen to the mature size of our cow herd?

  4. Animal Science Introductory Courses Quail Project

  5. Project Selection for 6 week weight. 3 lines: High growth, Low growth, Control 5 generations of selection

  6. Selection Selection was based on the individuals own performance. h2 of 6 week weight about 50% The accuracy of the selection criteria is 0.70

  7. Lecture 23 Correlated Response

  8. Question: What happens to other traits when selection is for one trait?

  9. Question: What happens to other traits when selection is for one trait? y x

  10. Question: What happens to other traits when selection is for one trait? select on x y Selection Differential for Y x

  11. Correlated Response

  12. Correlated Response • change in one trait resulting from selection on another trait

  13. Correlated Response • change in one trait resulting from selection on another trait • response can often be undesirable • example: turkeys

  14. Correlated Response • change in one trait resulting from selection on another trait • response can often be undesirable • example: turkeys • response is based on genetic covariance between traits • BVx,BVy

  15. Correlated Response Why does a genetic covariance exist?

  16. Correlated Response Why does a genetic covariance exist? 1) Pleotrophy -- one gene influences more than one trait (permanent)

  17. Correlated Response Why does a genetic covariance exist? 1) Pleotrophy -- one gene influences more than one trait (permanent) 2) Linkage -- genes influencing two traits physically linked (temporary)

  18. Correlations Positive verses negative correlations Beneficial verses antagonists correlations

  19. Correlated Response bBVy on BVx = BVy,BVx 2BVx

  20. Correlated Response bBVy on BVx= BVy,BVx 2BVx = change in BVy per unit change in BVx

  21. Correlated Response bBVy on BVx = BVy,BVx 2BVx = change in BVy per unit change in BVx CRy = bBVyon BVx G (per generation) = bBVy on BVx g (per year) x x

  22. Revisit the Quail Project

  23. Correlated Response

  24. What is my dogs name?

  25. Superior 3 Huron 2 Ontario 1 Dog = Rowdy

  26. Selection versus Mating Systems

  27. Selection Objective: change gene frequency

  28. Selection Objective: change gene frequency -- Change in frequencies for quantitative traits is slow. --

  29. Genetic Merit =

  30. Genetic Merit = value of individual genes (selection)

  31. Genetic Merit = value of individual genes (selection) + value of gene pairs (mating systems)

  32. Genetic Merit = value of individual genes (selection) + value of gene pairs (mating systems) + value of combination across loci (mating system)

  33. Mating Systems

  34. Mating Systems • Planned matings of selected parents

  35. Mating Systems • Planned matings of selected parents • Objective: optimize gene combinations

  36. Mating Systems • Planned matings of selected parents • Objective: optimize gene combinations • Three Example Systems: • Inbreeding • Line breeding • Cross breeding

  37. Inbreeding -- the systematic mating of related animals

  38. Inbreeding -- the systematic mating of related animals generation Full Sibs A B C D 0

  39. Inbreeding -- the systematic mating of related animals generation Full Sibs A B C D 0 E F 1

  40. Inbreeding -- the systematic mating of related animals generation Full Sibs A B C D 0 E F 1 G H 2

  41. Inbreeding Each generation animals become more related to each other, hence each generation the inbreeding coefficient becomes larger. Remember that the inbreeding coefficient is ½ the relationship of the parents.

  42. Inbreeding Fx Generation Selfing F.S. H.S. 0 0 0 0

  43. Inbreeding Fx Generation Selfing F.S. H.S. 0 0 0 0 1 .5 .25 .125

  44. Inbreeding Fx Generation Selfing F.S. H.S. 0 0 0 0 1 .5 .25 .125 2 .75 .38 .220

  45. Inbreeding Fx Generation Selfing F.S. H.S. 0 0 0 0 1 .5 .25 .125 2 .75 .38 .220 … 5 .97 .67 .450

  46. Inbreeding With a line, animals become more similar (uniformity), because gametes of any individual become more similar.

  47. Inbreeding With a line, animals become more similar (uniformity), because gametes of any individual become more similar. Line 1 2 3    F.S. F.S. F.S.

  48. Inbreeding Between lines individuals become more dissimilar (homozygous at different loci for different alleles). Line 1  2  3    F.S. F.S. F.S.

  49. Inbreeding • Using the inbreeding coefficient at generation t, we can estimate: • Within line variation, 2BVW(t) • Between line, 2BVB(t) • Total genetic variation, 2BVT(t)

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