Abstract
Described are data in a retrospective study of the epidemiology of dystocia, retained placenta, metritis, cystic follicle and luteal cyst. The 2960 lactation records by 1401 registered Holstein cows in 20 commerical herds were from the Canadian Record of Performance, and the disease data were from the head health program of the Ontario [Canada] Veterinary College. Means and standard deviations of production variables were given for days dry calving interval breed class average for milk, fat and days in milk. Rates of disease per lactation were dystocia 5.0% retained placenta 7.1%, metritis 13.8%, cystic follicle 12.9% and luteal cyst 3.2%. The distribution of calving ages suggested that the annual herd turnover was 20 to 25%. The distribution of diseases per lactation suggested that diseases occurred together in lactations more often than expected.