Genetic variation in incidence of daggy sheep - an indicator of
genetic resistance to parasites?
H.H. Meyer, T.G. Harvey, J.E. Smeaton
Ruakura Animal Research Station, Ministry of Agriculture and
Fisheries, Hamilton
Proceedings of the New Zealand Society of Animal Production.
1983, 43: 87-90
About 4000 ewes born over 3 years to single sire matings were
repeatedly scored for incidence and severity of dags. Dag scores were
analysed for evidence of genetic variation and relationship to
structural and performance characteristics. Perendales were found to
have lowest incidence of dags followed by Booroola x Perendales,
Booroola x Romneys and then Romneys and Border Leicester x Romney ewes.
There was no relationship between dag score and either wool or body
weight characteristics, either within or between breeds. Among progeny
of 6 Romney strain, daughters of Ruakura High Fertility rams had
substantially lower incidence with little variation among the rest. It
is suggested that long-term selection for fertility in this line has
reduced incidence of dags through improved utilisation of forage,
possibly as a result of resistance to internal parasites. The mean
heritability of dag score was 0.31 with a range of 0.13 to 0.60,
indicating that selection would be effective in reducing the incidence
of dags and their associated costs to farmers.
Keywords: NZSAPAB;
Dags; sheep parasites; crutching; flystrike; sheep breeds; wool
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Last Updated 03-05-1997
