Dagginess studied for breed differences

Press, 11 February 1983, Page 23

Dagginess studied for breed differences

Perendale flocks, or flocks selected for multiple births, may be less prone to dags than others. This is the conclusion of a study carried out by Ruakura Agricultural Research Centre scientists to see why some sheep are more prone to dagginess than others. Dr Howard Meyer, Mrs Jan Smeaton and Mr Tim Harvey presented their findings in a paper to delegates at the New Zealand Society of Animal Production Conference last week. They said daggy sheep are an economic burden to farmers. Reduced wool returns, losses through flystrike and labour for additional crutching and dagging cost an estimated 60 cents per stock unit. Of the 4000 ewes tested. Perendales had the lowest incidence of dags. They were followed by Booroola Cross Perendales, Booroola Cross Romneys, and the Romneys and Border Leicester Cross Romney ewes. “There was no relationship between dag score and either wool or body weight characteristics, either within or

between breeds," the scientists said. There was a proven relationship between dags and parasitism but diarrhoea and dags were not necessarily caused by internal parasites and not all internal parasites caused diarrhoea. The scientists noted that probably the most interesting finding was the much lower incidence of dags in Ruakura Romney high, fertil-ity-sired ewes compared to the other strains. The Ruakura high fertility strain has been maintained as a closed flock and selected for multiple births for 35 years. Selection for multiple births could be the key factor with this group, the scientists said. “Hence any factor likely to favour higher ovulation rate would be selected for and factors such as parasitism susceptibility or digestive inefficiencies would be selected against." Studies are now underway to examine the relationship between dagginess and worm burdens assessed through faecal egg counts and autopsy procedures.