FROM THE FARM REPORT: USING AUTOMATED ESTRUS ALERTS TO OPTIMIZE REPRODUCTIVE MANAGEMENT

Automated activity monitoring systems have become a common management tool on many herds and are often used to detect estrus and ovulation of cows more easily. These tools can help identify groups of cows that may act and respond differently to common reproductive practices and potentially be managed under a more individualized or targeted approach.

Two subgroups that might be identified are those that show signs of estrus within the defined voluntary waiting period (VWP) and those that do not. Previous research indicates that cows that show signs of estrus during the VWP are more likely to conceive at estrus and may not need hormonal interventions. Meanwhile, cows that do not show signs of estrus within the VWP may require intensive synchronization to enhance fertility under timed artificial insemination.

A recent meta-analysis published in the Journal of Dairy Science (2025.27545) used six papers with over 8,621 cow records to evaluate reproductive outcomes based on estrus detection during the VWP. The authors looked at the proportion of cows inseminated upon estrus detection detected by the activity monitor at first service, the pregnancy per artificial insemination at first service, and the proportion of cows pregnant within 150 days in milk. The dataset includes both first and greater lactation cows with VWP ranging from 40 to 60 days in milk and artificial insemination after the VWP.

The overall proportion of cows used in the analysis that did not have a detection of estrus during the VWP was 36.6% while 63.4% were detected. Across the studies included there was a wide range of cows not detected, 20.7 to 52.8%.

Cows that had estrus detected in the VWP were 3.36 times more likely to receive artificial insemination upon estrus detection at first service, were 1.59 times more likely to conceive at first service and were 1.75 times more likely to be pregnant at 150 days in milk compared to cows that had not been flagged for estrus.

Cows that resume cycling in the earlier postpartum period typically have experienced adequate physiological adaptation in terms of positive energy balance, inflammation, and uterine health. Meanwhile, cows that do not show signs of estrus may have had risk factors like stillbirth, retained placenta, metritis, body condition loss, lameness, and ketosis.

Overall, cows that were flagged for an estrus event in the VWP showed improvement in reproductive outcomes, highlighting the utility of these tools in reproductive management programs. There may be some differences in terms of the sensitivity of systems to detect estrus but also considerable variation in the incidence of no estrus during the VWP on farms. This may be due to different durations of VWP and other reproductive and health management. However, across a large number of animals there is great utility in using this metric as a benchmark and potentially allowing modified management of cows based on detection of estrus in the VWP to not only reduce hormone usage (and cost) but also create a target approach for cows that are more or less likely to reproductively successful in the herd.

— Sarah Morrison

morrison@whminer.com