Inactive ovaries in high-yielding dairy cows before service: aetiology and effect on conception

The overall rate of inactive ovaries diagnosed by two consecutive rectal examinations was 8.5 per cent for 7751 lactations. Inactive ovaries had an inverse association with increasing parity and were directly associated with twinning, retained placenta, primary metritis and high milk yield after calving in heifers. No independent associations were established with stillbirth, a low milk yield in the last 120 days before calving, a long dry period, ketonuria or a high serum glutamate oxaloacetate transaminase activity in the first week after calving. The presence of inactive ovaries in the previous lactation was a significant predictor of the trait. Cows with either metritis or inactive ovaries were at a greater independent risk of not conceiving within 150 days after calving and the combined risk associated with both factors was higher than their sum. It is concluded that while damage to the uterus repeatability and an energy shortage after calving are responsible for ovarian inactivity, this trait was not associated with fatty liver. Such an association could be due to an indirect causal relationship, the outcome of post parturient uterine diseases which are associated independently with overfeeding before calving and inactive ovaries.