Turn your Late Calvers into Great Calvers

Introduction

Late-calving cows pose a significant challenge for seasonal-calving dairy herds. If these cows fail to conceive early enough, they risk culling, leading to financial losses and disruptions to herd structure.. This case study examines whether targeted support using AHV’s SLAM-B protocol can help ‘problem cows’ calve earlier, and stay in step with the rest of the herd. A successful outcome would:

• Reduce costs associated with extended calving intervals

• Improve reproductive efficiency

• Retain valuable cows in the herd

Case Study Overview

On a Welsh grazing Friesian Holstein herd operating within an autumn calving system, the 20 latest-calving cows from the 2024 season—previously identified as ‘problem cows’——were selected for intervention with the AHV SLAM-B protocol

• At calving: StartLac, Aspi, and Metri

• 2–3 weeks post-calving: Booster tablet

To measure the impact of AHV support, these cows were compared to their own performance from the previous year. Key reproductive metrics, including calving dates, days to first service, and insemination success, were recorded for two consecutive years. Statistical analysis (Mann-Whitney U tests) was used to compare year-on-year differences, assuming that cows conceived on their final recorded service.

Results & Key Findings

On average, the cows, when supported with AHV products, were seen in heat and inseminated 34.3 days sooner. The difference in time to first service was highly statistically significant (U = 47.5, p = 0.00012). The 95% Confidence Limits (error bars in the graph) also reduced substantially, showing that the variability between cows decreased, meaning cows came into heat in a more predictable manner.

On average, the cows, when supported with AHV products, had 90.1 fewer open days.
The difference in time to first service was highly statistically significant (U = 4, p < 0.00001).
Again, the 95% Confidence Limits reduced very substantially, indicating that cows conceived at far more predictable intervals, effectively creating a ‘synchronization’ effect.

On average, the cows, when supported with AHV products, required 1.1 fewer straws per conception. In all graphs shown, last year’s results are depicted by the blue bar on the left and this year’s results (supported by AHV products) by the green bars on the right. Any error bars give the 95% confidence limits.

Return on Investment (ROI) Potential

The financial implications of improving reproductive efficiency are significant;

1. Retention of Cows in the Herd
   • The most critical financial gain comes from keeping cows that would have otherwise been culled. This factor is difficult to quantify with the current dataset but is likely the biggest driver of ROI.
2. Reduced Costs from Shortened Calving Intervals
   • The estimated cost of an open day is £5.00 per cow per day for this lower-input, grass-based system. With an average saving of 90.1 days per cow, this equates to £315.35 saved per cow.
3. 26 Fewer AI Straws Used
   • 26 fewer AI straws were used, saving an estimated £260 (£13 per cow), based on the assumption that first services used sexed semen and subsequent services used beef semen (£10 per straw).

Total Calculated Savings per Cow

ROI: 4.9x (without accounting for saved cows, meaning the real ROI is likely even higher)

£328.35 per cow saved

Total investment per cow: £55.50

Discussion & Practical Takeaways

This case study suggests that AHV’s SLAM-B protocol played a significant role in improving reproductive performance in late-calving cows. While additional factors such as nutrition, AI technique, and heat detection also contribute to outcomes, the consistent improvements despite challenging grass conditions suggest that AHV products were instrumental in ‘turning these cows around.’

For dairy farmers struggling with late-calving cows, the implications are clear:

• Better reproductive performance reduces culling pressure

• Improved calving intervals enhance herd fertility and productivity

• Significant cost savings can be achieved through fewer open days and reduced AI usage

By integrating AHV’s SLAM-B protocol into your transition and fertility management strategy, you could see tangible improvements in herd reproductive performance, cow retention, and overall profitability.

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