An examination of genetic trend in a herd of range Hereford cattle

LIST OF TABLES 1. Summary of heritability estimates for weaning weight and score 13 2. Estimates of heritability for yearling traits 14 3. Mean squares, repeatabilities and heritabilities for weaning and yearling traits 23 4. Least squares means for weaning traits from Model I 24 5. Least squares means for yearling traits from Model I 2 5 6.Linear regression coefficients for weaning and yearling traits from Method I -Models I, II and III 26 7. Estimates of genetic and environmental trends for weaning and yearling traits -Method I 29 8. Estimtes of phenotypic, genetic and environmental trends for weaning traits from Models I and IV 32 9. Estimates of phenotypic, genetic and environmental trends for weaning and yearling traits from Method III 34 APPENDIX TABLES 1. Mean squares for weaning traits from the analysis of variance of Model I -years 47 2. Mean squares of yearling traits from the analysis of variance of Model I -years 47 3. Mean squares for weaning traits from the analysis of variance of Model II -dams 48 4. Mean squares for yearling traits from the analysis of variance of Model II -dams 49 IV 5. Mean squares for weaning traits from the analysis of variance of Model III -sires 50 6.Mean squares for yearling traits from the analysis of variance of Model III sires 51 7. Mean squares for weaning traits from the analysis of variance of Model IVrepeat matings 52 8. Mean squares for weaning traits from the analysis of variance of Model Vwith sires included 52 9. Mean squares for yearling traits from the analysis of variance of Model Vwith sires included 53 10.Mean squares for weaning traits from the analysis of variance of Model Vwithout sires 53 11.Mean squares for yearling traits from the analysis of variance of Model Vwithout sires 54 LIST OF FIGURES 1. Change in adjusted weaning weight (WWA) over birth years of calves 55 2. Change in adjusted weaning score (WSA) over birth years of calves 56 3. Change in adjusted yearling weight (YWA) over birth years of calves 57 4. Change in postweaning daily gain (PWDG) over birth years of calves 58 5. Change in yearling score (YS) over birth years of calves 59 VI CHAPTER I