Genetic parameters for growth traits and litter size in Danish Texel, Shropshire, Oxford Down and Suffolk

In this study, heritabilities and (co)variance components for birth weight (BW), average daily gain from birth until 2 months (ADG2) and litter size (LS) were estimated in Danish Texel, Shropshire, Oxford Down and Suffolk. Data from 1990 to 2004 were extracted from the sheep recording database at the Danish Agricultural Advisory Centre. A multivariate animal model was used to estimate genetic parameters, including both direct and maternal additive genetic effects, common litter effects and permanent environmental effects. Average values ranged from 4.20 to 4.68 kg for BW, from 281 to 333 g for ADG2 and from 1.36 to 1.55 lambs for LS. Direct and maternal heritabilities for BW for all breeds were in the range from 0.16 to 0.19 and from 0.15 to 0.20. Direct and maternal heritabilities for ADG2 ranged from 0.14 to 0.30 and from 0.09 to 0.16. The heritability for LS ranged from 0.04 to 0.06. Both direct genetic correlations between BW and ADG2, and maternal genetic correlations between BW and ADG2 were positive for all breeds. Genetic correlations between LS and direct genetic effects on BW were not significant different from zero, but the genetic correlation between LS and maternal genetic effects on BW were positive and favourable.