Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1978 Individual and maternal heterosis estimated from single crosses and backcrosses of swine James Franz Schneider Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Agriculture Commons, and the Animal Sciences Commons Recommended Citation Schneider, James Franz, "Individual and maternal heterosis estimated from single crosses and backcrosses of swine " (1978). Retrospective Theses and Dissertations. 6520. https://lib.dr.iastate.edu/rtd/6520 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. 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University Microfilms International 300 North Zeeb Road Ann Arbor. Michigan 48106 USA St. John's Road. Tyler's Green High Wycombe. Bucks. England HP10 8HR 79vU21u SCHNEIDE2; JAMES FRAWZ iNDlVlfUAL AND MATERIAL "ETLRUSIS ESTIMATED FROM SINGLE CHDSSES AND RACKCKBSSES OF IÙ4* ST.'iTt I'^'IVEPSTTY, PH.O,, 197b University Micrmlms International SOON ZEEBROAD,ANNARBOR.MI48IO6 Individual and maternal heterosis estimated from single crosses and backcrosses of swine by James Franz Schneider A Dissertation Submitted to the Graduate Faculty in Partial Fulfillment of The Requirements for the Degree of DOCTOR OF PHILOSOPHY Department: Animal Science Major: Animal Breeding Approved : Signature was redacted for privacy. In Charge of Major Work Signature was redacted for privacy. For the Major Departrn'sat Signature was redacted for privacy. For the Graduate College Iowa State University Ames, Iowa 1978 ii TABLE OF CONTENTS Page INTRODUCTION 1 LITERATURE REVIEW 3 Genetic Effects of Crossbreeding 3 Non-Genetic Effects on Swine Performance 13 DESCRIPTION OF THE EXPERIMENT 15 Design of the Experiment 16 Individual Pig Measurements 19 Litter Measurements 21 Carcass Measurements 22 STATISTICAL METHODS 24 RESULTS AND DISCUSSION 30 Individual Pig Traits 33 Litter Traits 54 Carcass Traits 76 SUMMARY AND CONCLUSIONS 97 Non-Genetic Effects 97 Genetic Effects 100 LITERATURE CITED 106 ACKNO\-/LEDGMENTS 110 APPENDIX 111 iii LIST OF TABLES Table Page 1. Mating design for one season of Phase I 16 2. Mating design for one season of Phase II - crossbred sires only 18 3. Mating design for one season of Phase II - crossbred dams only 18 4. The distribution of sires and litters that produced pigs of market age during four seasons of Phase I 31 5. The distribution of sires and litters that produced pigs of market age during three seasons of Phase II - crossbred sires only 32 6. The distribution of sires and litters that produced pigs of market age during three seasons of Phase II - crossbred dams only 32 7. Means and effects of year, season and year-season interaction—individual pig traits 34 8. R-squares and effects of general combining ability, breed of maternal grandparent and maternal ability, and the correlation of general combining ability with maternal ability—individual pig traits 37 9. Deviations of the residual purebred effect, inbreeding, individual heterosis and breed specific heterosis— individual pig traits 42 10. Effects of specific combining ability and specific heterosis—individual pig traits 45 11. Effects of maternal heterosis, parity and the parity- maternal heterosis interaction—individual pig traits 48 12. Effects of sex, sex-individual heterosis interaction and sex-maternal heterosis interaction—individual pig traits 50 iv Table Page 13. Sex differences for each mating type and heterosis estimates for each sex—selected traits 53 14. Means and effects of year, season and the year-season interaction—litter size 55 15. Means and effects of year, season and the year-season interaction—total litter weight 57 16. R-squares and effects of general combining ability, breed of maternal grandparent and maternal ability, and the correlations of general combining ability with maternal ability—litter size 58 17. R-squares and effects of general combining ability, breed of maternal grandparent and maternal ability, and the correlations of general combining ability with maternal ability—total litter weight 61 18. Deviations of the residual purebred effect, inbreeding, individual heterosis and breed specific heterosis— litter size 63 19. Deviations of the residual purebred effect, inbreeding, individual heterosis and breed specific heterosis— total litter weight 65 20. Effects of specific combining ability and specific heterosis—litter size 67 21. Effects of specific combining ability and specific heterosis—total litter weight 69 22. Effects of maternal heterosis, parity and the parity- maternal heterosis interaction—litter size 71 23. Effects of maternal heterosis, parity and the parity- maternal heterosis interaction—total litter weight 73 24. Further examination of the parity-maternal heterosis interaction—selected litter weight traits 75 25. Means and effects of year, season and the year-season interaction—carcass traits 78 V Table Page 26. R-squares and effects of general combining ability, breed of maternal grandparent and maternal ability, and the correlation of general combining ability with maternal ability—carcass traits 80 27. Deviations of the residual purebred effect, inbreed­ ing, individual heterosis and breed specific heterosis—carcass traits 84 28. Effects of specific combining ability and specific heterosis—carcass traits 87 29. Effects of maternal heterosis, parity and the parity- maternal heterosis interaction—carcass traits 89 30. Effects of sex, sex-individual heterosis interaction and sex-maternal heterosis interaction—carcass traits 92 31. Sex differences for each mating type and heterosis estimates for each sex—selected carcass traits 94 32. Effects of the sex-general combining ability inter­ action and the regression on slaughter weight— carcass traits 112 33. Mean squares and tests of significance from the analysis of variance—individual pigs 114 34. Mean squares and tests of significance from the analysis of variance—litter size 115 35. Mean squares and tests of significance from the analysis of variance—litter weight 116 36. Mean squares ard tests of significance from analyses of variance—carcass traits 117 37. Means for Phase I breed combinations—individual pigs 119 38. Means for Phase II breed combinations—individual pigs 120 39. Means for Phase I breed combinations—litter size 121 40. Means for Phase I breed combinations—litter weight 122 vi Table Page 41. Means for Phase II breed combinations—litter size 123 42. Means for Phase II breed combinations—total litter weight 124 43. Means for Phase I breed combinations—carcass traits 125 44. Means for Phase II breed combinations—carcass traits 127 1 INTRODUCTION Research on swine crossbreeding was begun as early as the late 1890's, but swine producers did not seriously consider the use of cross­ breeding until hybrid seed corn was introduced in the late 1930's. Apparently the phenomenal success of crossbreeding with seed corn forced the swine industry to critically review the earlier swine research and implement those recommendations. The acceptance and success of cross­ breeding in swine is evident today by the fact that approximately 95 per­ cent of the market hogs produced in the United States are crossbred. Crossbreeding has three major advantages. The first and most obvious advantage is the production of individual and maternal heterosis,