Genetic parameters were estimated for 35-, 42-, 50-, 100- and 150-day weigh
t in the South African Mutton Merino breed. The direct heritability estimat
es obtained were 0.270, 0.366, 0.278, 0.185 and 0.115 respectively. The mat
ernal heritability estimates for the respective weights were 0.494, 0.249,
0.129, 0.091 and 0.080. The correlation between the animal effects (direct
and maternal) varied between -1.000 for 36-day weight to -0.376 for 150-day
weight. Very little selection progress was made over the period (1980-1999
) in the breed.