29/06/2026
*Impact of increased days open*
Reduced profitability
More non-productive days increase feeding and management costs without producing another calf.
Lower lifetime milk production efficiency.
Longer calving interval
Increased days open directly lengthens the calving interval.
Fewer calves are born over the cow's lifetime.
Reduced lifetime productivity
Cows produce fewer lactations during their productive life.
Genetic improvement slows because fewer replacement calves are available.
Higher culling risk
Cows failing to conceive are more likely to be culled for reproductive reasons.
Increased insemination and veterinary costs
More services per conception.
Additional pregnancy diagnosis, synchronization, and treatment expenses.
Lower herd reproductive efficiency
Delayed pregnancies reduce the percentage of pregnant cows in the herd.
More cows remain in late lactation, where milk production is naturally lower.
Economic impact
Every extra day open beyond the target can cost approximately US$2–5 per cow per day, depending on milk price, feed costs, and farm management.
Target days open
Excellent: 85–110 days
Acceptable: 110–130 days
Problematic: More than 130–150 days (depending on the farm's voluntary waiting period and breeding goals)
Strategies to reduce days open
Detect estrus accurately.
Maintain proper transition cow management.
Improve nutrition and body condition.
Diagnose pregnancy early.
Treat postpartum reproductive disorders promptly.
Use timed AI protocols where appropriate.
Keep accurate reproductive records.
