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The epidemiology of ovine brucellosis was investigated in 6 ram flocks in which anomalous reactions to the complement fixation test was recorded. It was shown that rams can become infected as young as 4 months of age. Naturally infected animals have an epididymitis and excrete Brucella ovis in their semen or they may only show a serological response for a short time then recover. The base line titres of chronically infected animals stay relatively constant. The importance of abortive infection and possible reinfection is discussed.

Thyroxine levels in serum of lambs and ewes were measured to determine their usefulness in assessing iodine nutrition of sheep. Lambs born on properties with no history of goitre had serum thyroxine concentrations more than twice that recorded in their mothers. These high values decreased to a level similar to that in the ewes after 8 weeks. In goitrous lambs younger than 2 weeks old, serum thyroxine concentrations were less than their ewe levels. Lambs born to ewes supplemented with iodine during pregnancy had higher thyroxine levels than lambs of control ewes. A survey of 80 flocks of ewes in Victoria showed that 40% had a low mean thyroxine concentration (less than 50 nmol/l), but only one of these properties had reported an outbreak of goitre. It is suggested that serum thyroxine levels in newborn lambs may provide a more sensitive indicator of hypothyroidism associated with iodine deficiency than ewe levels.

A trial was carried out to determine whether selenium responsive unthriftiness existed on a property in the Strathbogie ranges of Central Victoria where unthriftiness of young sheep has been a problem for 10 to 20 years. White muscle disease had been diagnosed on the property in the previous year and on other properties in the area. Eighty Merino ewes and lambs were allotted to one of 4 groups in a 2 x 2 factorial designed trial in which sodium selenite (0.1 mg/kg) was given orally to ewes and/or lambs at marking time and to treated lambs at 3 monthly intervals thereafter. Selenium treatment of the ewes had no significant effect on subsequent lamb performance. Selenium treatment of the lambs produced significant responses: mortality in treated groups was 0% compared with 17.5% in untreated groups; body weight gains were 1.9 kg higher at both weaning and one year of age in treated than in untreated lambs; mean fleece weight was 14.4% higher in treated lambs and they produced 39% more wool than the surviving untreated lambs.