Sex and age effects on genetic parameters for wool production
and qualities
J.N. Clarke, J.L. Dobbie, K.R. Jones, A.L. Wrigglesworth and
S.M. Hickey
AgResearch, Ruakura Agricultural Research Centre, P B 3123,
Hamilton, New Zealand
Proceedings of the New Zealand Society of Animal Production. 1999, 59: 23-26
Heritabilities and genetic correlations were estimated for New
Zealand Romney sheep from within the selected and control lines of a
25-year selection experiment for greasy hogget fleece weight and
yearling body weight. Average repeatability of clean fleece weight in 1
to 5 year-old ewes was 0.56, 25% higher than the average heritability of
0.44. The average genetic correlation among measurements at different
ages was 0.89. Sexual dichotomy in the relative predictive power of
hogget records was most apparent for greasy and clean fleece weights but
was evident to some degree for bulk and brightness as well, due mainly
to lower heritabilities in male compared to female hoggets. Average
co-heritability of greasy hogget with adult clean fleece weights was 25%
lower for male (0.26) compared to female (0.35) hoggets, in this case
due to a lower genetic correlation (0.69 vs 0.81) as well as a lower
heritability (0.33 vs 0.43, respectively). A repeatability model seemed
an adequate approximation for estimation of breeding merit for most wool
quality traits studied but not for lifetime wool production.
Keywords: NZSAPAB;
genetic parameters; male and female hoggets; wool production and
qualities.
Last Updated 06-08-1999
