EVALUATION OF DORMER SIRES FOR LITTER SIZE AND LAMB MORTALITY USING ATHRESHOLD-MODEL

Heritability estimates and breeding value predictions of Dormer sires for litter size and lamb mortality were obtained using a threshold mod el. Heritability estimates on the underlying scale were 0.24 and 0.12 for litter size and mortality, respectively. Breeding value prediction s varied between 0.41 sigma(e)2 and -0.43sigma(e)2 for litter size and 0.30sigma2e2 and -0.14sigma(e)2 for lamb mortality. Probability distr ibutions for progeny of sires across 'fixed effects' were also calcula ted. It is concluded that a threshold model can effectively be applied for routine evaluation of Dormer sires for categorical traits.