Genetic analyses for growth traits of two indigenous beef cattle breeds in Botswana

Genetic parameters for birth weight (BW), weaning weight (WW), pre-weaning average daily gain (ADG1), 18-months weight (18 MW) and post-weaning average daily gain (ADG2) were estimated using single-trait and multi-trait analyses. Data consisted of 2257 records for the Botswana Composite and 5923 records for the Tswana collected between the period of 1988 and 2006. The individual animal model (AM) and animal maternal model (AMM) were fitted in both analyses. Direct heritabilities for BW, WW, ADG1, 18 MW and ADG2 in the Tswana were respectively 0.45, 0.36, 0.37, 0.31 and 0.31, when the AM was fitted in single-trait analyses. Fitting the AMM gave direct and (maternal) heritabilities of respectively 0.31(0.11), 0.20(0.15) and 0.16(0.21) for BW, WW and ADG1 in the Tswana breed. Direct heritabilities for BW, WW and ADG1 in the Composite when the AM was fitted in single-trait analyses were respectively 0.58, 0.32 and 0.30. Direct and (maternal) heritabilities when the AMM was fitted for single-trait analyses in the Composite were 0.55(0.09), 0.17(0.15) and 0.14(0.15), respectively. When using multi-trait analyses and fitting the AM, the direct heritabilities for the Tswana were respectively 0.45, 0.37, 0.34, 0.39 and 0.31 for BW, WW, ADG1, 18 MW and ADG2. Genetic correlations among the live weight and growth traits ranged from 0.16 to 0.97. Direct and (maternal) heritabilities for BW, WW and ADG1 were respectively 0.31(0.11), 0.19(0.15) and 0.14(0.17) in the Tswana using the multi-trait analysis. Correlations between direct heritabilities for BW, WW and ADG1 ranged from 0.45 to 0.95 while maternal correlations ranged from 0.12 to 0.99. The magnitude of the heritabilities indicates an opportunity to make genetic progress through selection. (C) 2010 Elsevier B.V. All rights reserved.