Dairy cows that have had a normal calving event and are healthy and well managed return to normal cyclicity within 15-20 days of calving. The first heat should be observed from approximately day 25 after calving and then normally occurs at 18-24 day intervals thereafter.
On average 50-80% of cows within a herd fall into this category, with the balance of cows having delayed resumption of ovulation. A proportion of cows, given time, will repair any minor damage to the reproductive system after calving. Some, however, do need intervention to ensure that they resume cycling in time for the breeding season.
Early identification of non-cycling cows enables earlier intervention pre-breeding maximising submission and pregnancy rates. Failure or late identification of these “problem” cows will result in an extended calving season, a shortened lactation number and increase the likelihood of eventually culling the cow.
The most common reasons for delayed resumption of cyclicity are excessive loss of body condition, and/or severe metabolic/disease insults in the early postpartum period.