Early pregnancy diagnosis in cattle

Progesterone concentrations in peripheral plasma and in milk were determined by competitive protein-binding assay each day throughout the oestrous cycle of heifers and a dairy cow and also in animals after insemination. The accuracy of detecting and forecasting pregnancy and non-pregnancy was assessed in studies involving blood-sampling of heifers on the 20th and 23rd day after artificial insemination, and milk sampling of cows on the 21st and 24th day after mating. The high degree of accuracy obtained using this procedure for an early pregnancy diagnosis would be particularly useful in herds involved in a controlled breeding programme.