Estimates of covariance components and genetic parameters for growth traits in Tswana cattle selected for increased weaning or eighteen-month weights

The objective of this study is to estimate variance-covariance components and genetic parameters for growth traits in Tswana cattle. Genetic analyses average daily gain (ADGs) were conducted using 7223 records animals which born between 1996 2013 from 1662 dams 188 sires 54 contemporary groups. Both univariate bivariate animal models used. Heritability estimates ranged 0.12±0.03 BWT 0.45±0.03 EWT while those obtained ADGs 0.24±0.03 0.31±0.04 ADG1 ADG2, respectively. Permanent maternal environmental effects significant WWT ADG1. Substantial observed BWT, correlations among 0.19±0.07 0.99±0.02 Phenotypic 0.19±0.01 0.94±0.01 two selected lines significantly improved annual all the was optimally enhanced S2 than S1. control line exhibited not anticipated perhaps attributed asymmetry selection response. variations suggesting that improvement can be attained through rate. High indicated one these may result indirect correlated response on other traits. Key words: Bivariate analysis, correlations, heritability, indigenous cattle, effects, variation.