Bell Ranch: Integrated Seedstock and Commercial Programs

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

8. Lecture 23 Correlated Response

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

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

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

12. Correlated Response

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

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

15. 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

16. Correlated Response Why does a genetic covariance exist?

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

18. 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)

19. Correlations Positive verses negative correlations Beneficial verses antagonists correlations

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

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

22. 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

23. Revisit the Quail Project

24. Correlated Response

25. What is my dogs name?

26. Superior 3 Huron 2 Ontario 1 Dog = Rowdy

27. Selection versus Mating Systems

28. Selection Objective: change gene frequency

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

30. Genetic Merit =

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

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

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

34. Mating Systems

35. Mating Systems • Planned matings of selected parents

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

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

38. Inbreeding -- the systematic mating of related animals

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

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

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

42. 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.

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

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

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

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

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

48. 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.

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

50. 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)