Article Sidebar
Article Details
Issue
Section
Articles
Copyright @ Bachudo Science Co. Ltd. This work is licensed under the creative commons Attribution 4.0 International license.
Main Article Content
Non-genetic factors and correlation studies in cattle
Abstract
The data comprised of 3272 birth weight (BWT), 3091 weaning weight (WWT), 2112 yearling weight (YWT) and 1978 eighteen month weight (18-MO) pedigree records were collected from an experimental indigenous Tuli cattle herd maintained at Matopos Research Station, Bulawayo, Zimbabwe, over the period 1988-1997 were used for this study. The mean BWT, WWT, YWT and 18-MO during the study period were from 28.14± 0.07 kg, 176.43± 0.07 kg, 176.58± 0.07 kg and 242.68 ± 0.07 kg with, respectively. It was found that sire, year of birth, sex of calf, age of dam
had significant effect (p<0.01) effect on all growth trait. It was inferred that male calves were significantly heavier than female calves. The birth weight and weaning weight were found to be highest in seven and eight year groups, respectively, and the lowest in three-year group. The inconsistency of literature estimates indicates the importance of estimation of environmental factors that affect growth traits within specific experimental herds and environment. Correction of environmental effects is necessary to increase accuracy for selection of growth traits in indigenous Tuli cattle.
In the development of any breeding plan knowledge of various properties of traits under consideration is required. Bivariate and multivariate analyses fitting an animal model, were conducted by means of (ASREML)
procedures to obtain the genetic correlations. The fixed effects included in the model were sex, year of birth and age of dam. Heritability estimates for growth traits associated with the bivariate analyses were higher than those obtained using multivariate analyses. The phenotypic correlations between growth traits from both bivariate and multivariate analyses were positive and, were moderate to high. The genetic correlation between birth weight and weaning weight was positive and moderate. The genetic correlation between birth weight and post-weaning growth traits were moderate and positive, indicating that these traits are not under exactly the same genetic control. Selection for yearling weight may increase birth weight due to positive indirect selection response and high heritability (h2
a). Birth weight is a good indicator of post-weaning growth traits in this herd.
had significant effect (p<0.01) effect on all growth trait. It was inferred that male calves were significantly heavier than female calves. The birth weight and weaning weight were found to be highest in seven and eight year groups, respectively, and the lowest in three-year group. The inconsistency of literature estimates indicates the importance of estimation of environmental factors that affect growth traits within specific experimental herds and environment. Correction of environmental effects is necessary to increase accuracy for selection of growth traits in indigenous Tuli cattle.
In the development of any breeding plan knowledge of various properties of traits under consideration is required. Bivariate and multivariate analyses fitting an animal model, were conducted by means of (ASREML)
procedures to obtain the genetic correlations. The fixed effects included in the model were sex, year of birth and age of dam. Heritability estimates for growth traits associated with the bivariate analyses were higher than those obtained using multivariate analyses. The phenotypic correlations between growth traits from both bivariate and multivariate analyses were positive and, were moderate to high. The genetic correlation between birth weight and weaning weight was positive and moderate. The genetic correlation between birth weight and post-weaning growth traits were moderate and positive, indicating that these traits are not under exactly the same genetic control. Selection for yearling weight may increase birth weight due to positive indirect selection response and high heritability (h2
a). Birth weight is a good indicator of post-weaning growth traits in this herd.
