DIRECT AND MATERNAL (CO)VARIANCE COMPONENTS AND GENETIC PARAMETERS FOR GROWTH TRAITS OF DORPER SHEEP IN SEMI-ARID KENYA

Abstract

Genetic and phenotypic parameters for lamb growth traits for the Dorper sheep were estimated from data obtained from the Sheep and Goats Station in Naivasha, Kenya. Traits considered were body weights at birth (BW0, kg), at 1 month (BW1, kg), at 2 months (BW2, kg), at weaning (WW, kg), at 6 months (BW6, kg), at 9 months (BW9, kg) and at yearling (YW, kg), average daily gain from birth to 6 months (ADG0–6, gm) and from 6 months to 1 year (ADG6–12, gm). Direct heritability estimates were, 0.18, 0.36, 0.32, 0.28, 0.21, 0.14, 0.29, 0.12 and 0.30 for BW0, BW1, BW2, WW, BW6, BW9, YW, ADG0–6 and ADG6–12, respectively. The corresponding maternal genetic heritability estimates for body weights up to 9 months were 0.16, 0.10, 0.10, 0.19, 0.21 and 0.18. Direct maternal genetic correlations were negative and high ranging between −0.47 to −0.94. Negative genetic correlations were observed for ADG0–6 and ADG6–12, BW2 and ADG6–12, WW and ADG6–12 and BW6 and ADG6–12. Phenotypic correlations ranged from 0.15 to 0.96. Maternal effects are important in the growth performance of the Dorper sheep though a negative correlation exists between direct and maternal genetic effects. The current study has provided important information on the extent of additive genetic variation in the existing flocks that could now be used in determining the merit of breeding rams and ewes for sale to the commercial flocks. The estimates provided would form the basis of designing breeding schemes for the Dorper sheep in Kenya. Keywords: Annual trends; Dorper sheep; (Co)variance components; Genetic parameters; Growth traits