The prevalence of bovine keratoconjuctivitis in a beef cattle herd in north eastern Queensland

The prevalnece and severity of IBK in a group of Shorthorn and crossbred (approximately 50% B. indicus) cows, steers and calves were observed during a 31-month period, from November 1970 to May 1973, in North Queensland. In both the wet summer and dry winter seasons, IBK prevalence was significantly higher for all classes of Shorthorn than crossbred animals. Prevalence was consistently highest during the wet summer months (peak February-March). Ninety-six per cent of Shorthorn cows contracted IBK and 53% severe IBK, compared with 53% and 7% respectively, of crossbreds. Permanent and temporary blindness occurred in 3% and 10% of Shorthorn cows, but not crossbreds were affected. The implications of these findings are also discussed.