Genetic Parameters for Growth Traits of Malya Goats and Heterosis from Crossbreds of Malya and Sukuma Goats

The study estimated heterosis of growth traits from crossbred progeny of MalyaxSukuma goats and heritability, genetic correlation and phenotypic correlation for growth traits of Malya goats in Maswa, Tanzania. The objective was to explore strategies for crossbreeding Malya goats with the Sukuma goats. Growth performance data recorded during the implementation of a crossbreeding project for parent breeds and crossbred off-springs were used to estimate the parameters. Positive heterosis was observed for birth weight (8.19%), yearling weight (9.59%), post-weaning growth rate (19.26%) and birth to yearling growth rate (9.62%), while negative heterosis was found for weaning weight (-10.92%), 32-weeks weight (-6.66%) and pre-weaning growth rate (-9.50%). Heritability estimates from sire variance components were 0.43±0.040 for birth weight, 0.23±0.028 for weaning weight, 0.11±0.020 for 32 weeks weight, 0.18±0.025 for yearling weight, 0.18±0.025 for pre-weaning growth rate,0.17±0.024 for post-weaning growth rate and 0.17±0.024 for birth to yearling growth rate. Genetic correlations between body weights ranged from 0.17±0.062 to 0.49±0.055, while the corresponding phenotypic correlations ranged from 0.10 to 0.61. Genetic correlations between growth rates for the different stages ranged from 0.39 to 0.90, whereas the phenotypic correlations ranged from -0.38 to 0.89. Genetic and phenotypic correlations (-0.39±0.058 and -0.38, respectively) between pre-weaning growth rate and post-weaning growth rate were negative. Genetic and phenotypic correlations between body weights at different ages, pre-weaning growth rate and birth to yearling growth rate, and post-weaning growth rate and birth to yearling growth rate were all positive. In conclusion, heterosis results showed that, birth weight, yearling weight and post-weaning growth traits benefited from the crossbreeding program. Heritability results showed birth weight and weaning weight were considerably controlled by additive genes and thus, in inferiorly performing breeds the traits can potentially be improved by breeding. Correlations among growth traits indicated promising correlated responses to selection.