MOIRA (the Management of Insemination through Routine Analysis) is a computer program that is a module of DAISY, the Dairy Information System. This decision support system uses the results of milk progesterone tests to determine when to inseminate cows. The MOIRA program plans a series of weekly tests for each cow, to check for cyclicity. Subsequently, the program lists cows for alternate day tests to identify the days when they should be served, and if necessary, a cow can be served without being seen in heat. The work which led to the development of MOIRA showed that ovulation detection rates of 98 per cent were achieved; in commercial herds the rate is around 85 per cent. As pregnancy rates were unchanged, the effect of MOIRA was to reduce calving to conception interval from 90 to 85 days and the culling rate for failure to conceive from 13 per cent to 5 per cent in one herd and from 104 to 100 days and 21 per cent to 12 per cent in another herd. The use of the program produced an estimated extra net profit for the farmers of pounds 52/cow in the first herd and pounds 54/cow in the second.