title: Growth of Mashona cattle on range in Zimbabwe. II. Estimates of genetic parameters and predicted response to selection.
abstract: For 1,456 Mashona calves sired by 88 bulls heritability estimates from paternal half-sibs were 0.44 +/- 0.11 for birth weight, 0.38 +/- 0.10 for 205-day weaning weight, 0.39 +/- 0.10 for 18-month weight, 0.37 +/- 0.10 for pre-weaning daily liveweight gain and 0.41 +/- 0.11 for daily gain from weaning to 18 months of age. Genetic correlations were relatively low for birth weight with weaning weight (0.42 +/- 0.18), 18-month weight (0.56 +/- 0.16), pre-weaning gain (0.33 +/- 0.19) and post-weaning gain (0.36 +/- 0.19). Higher genetic correlations were observed for pre-weaning gain with weaning weight (0.98 +/- 0.01) and 18-month weight (0.59 +/- 0.14) and for 18-month weight with weaning weight (0.67 +/- 0.12) and post-weaning gain (0.73 +/- 0.10). Post-weaning daily gain was not significantly correlated genetically with both pre-weaning gain (-0.11 +/- 0.22) and weaning weight (-0.03 +/- 0.22). With 10% retention of males and 60% of females expected genetic improvements per generation from direct selection for weaning weight or 18-month weight were 8.11 kg and 12.12 kg respectively. These improvements would be reduced by 18% and 35% if selection indices were used to produce no correlated change in birth weight.
authors: Makoholi Experiment Station, Masvingo, Zimbabwe.
authors: H P
authors: HP
authors: Tawonezvi
mesh_terms: D000818:Animals; D001724:Birth Weight; D001947:Breeding; D002417:Cattle / Q000235:genetics / Q000254:growth & development*; D005260:Female; D008297:Male; D010375:Pedigree; D010641:Phenotype; D014886:Weaning; D015430:Weight Gain; D015030:Zimbabwe