Survey of intramammary infections in ewes on the New England Tableland of New South Wales.

Samples of mammary secretion were collected aseptically from 1093 ewes in 8 separate flocks. Most of the ewes were suckling lambs 4 to 6 weeks old. Standard bacteriological tests were carried out on the samples to identify the organisms involved in intramammary infections. Data on age, breed, lactational status and clinical status of the gland and its secretion were recorded at the time of sampling. The prevalence of intramammary infection was 14% of ewes (8% of glands). There was a tendency for prevalence of intramammary infection to be positively correlated with age of the ewe (two-year-old and six-year-old ewes had, respectively, 4.4% and 14.0% of glands infected). This relationship was highly significant for Border Leicester x Merino ewes. There were also significant differences in infection prevalence between breeds. infected glands had a higher prevalence of clinical abnormalities of udder, teat and secretion than did non-infected glands. Staphylococcus aureus was overwhelmingly the most frequently isolated bacterium being responsible for 40% of all intramammary infections.