Common ground: Dairy-longevity takeaways from the 45th Discover Conference

Matt Lucy, PhD (University of Missouri), and Albert De Vries, PhD (University of Florida), were co-chairs of the 45th ADSA Discover Conference (DC45) on Dairy Cattle Lifespan: New Perspectives, which was dedicated to dairy cow longevity and took place in October 2023. The two conducted a recap session of the DC45 learnings and takeaways during the 2024 ADSA Annual Meeting. Want more on this topic? Look for a future Perspective paper in the Journal of Dairy Science that will condense the learnings and remaining questions raised during the closed-door sessions.

As previous attendees know well—and as Gail Carpenter, PhD, so beautifully phrased it—Discover Conferences operate on Fight Club rules: We do not talk about the specific details of our conversations once the session has wrapped, which grants us a rare chance to focus on a shared, singular issue, ask tough questions, and embrace an environment in which diverse viewpoints, nuance, and even disagreements are a strength, not a weakness.

Dairy cow lifespan is a topic with many facets, differing viewpoints, and unresolved questions—a shared optimum replacement rate remains a spectrum. As our industry continues advancing research and knowledge on this topic, we want to take you behind the curtain of DC45 to share the key moments of common ground, which was the focus of our recent DC45 recap platform session at this year’s ADSA Annual Meeting.

So, what do we all agree on? 

• Dairy cows produce two important parts of the human diet: milk and meat. Milk production is the primary purpose of dairy farms and an essential part of feeding the world. Nonetheless, the importance of meat from marketed dairy cows should not be understated; it serves as an important income stream for farms and a crucial source of beef for consumers.
• A farm thrives on healthy cows. Regardless of age and optimum replacement rates, all cows deserve the highest quality feeding, management, and veterinary care. A dairy cow with a productive and healthy life is the goal of the dairy farmers who care for them and the clear expectation of modern dairy consumers. For the sake of welfare, then, replacement rates should not be prioritized over cow health and well-being.
• Lifespan should be weighed in partnership with health, productivity, and profit. If you hold all things constant, regardless of production system, cows that make more milk solids—fat and protein—are more profitable. These high-production cows are the basis of a profitable and thriving dairy farm. Cows that are lower producing and less profitable than their herd mates should be replaced for economic reasons, even if they are healthy and high producing, to make space for more productive and profitable animals before their health starts to decline so they can contribute positively to the beef supply.
• The replacement heifer is the future of the dairy herd. We have made (and continue to make) huge strides in management, genetics, and fertility. Replacement heifers pave the way for tomorrow’s healthy, high-producing, genetically superior herds. They should be raised with care and the best possible genetics so they can improve tomorrow’s herd health and performance.  
• The optimal replacement rates—or the percentage of the herd that is replaced annually—differ across nations and production systems. Mathematical models designed to predict optimum replacement rates need to be sufficiently robust to accommodate production systems and dairy industries across different nations. A suitable replacement rate for a large US dairy is likely at least 30%, whereas the optimal replacement rate for an Irish grass-based dairy is considerably less than that (approximately 20%). The greater or lesser replacement rates should not be interpreted as greater or lesser cow health or welfare on the dairy.

Overall, we left the session proud to tell our story: Dairy, as a connected sector, has made huge strides and continues to push toward a shared goal of healthy and productive cows that provide high-quality and nutritious food for human consumption with minimal environmental impact.

ADSA Annual Meeting

As a dairy professional, staying up to date with the latest research and industry trends is essential to your success. Attending ADSA’s conferences gives you face-to-face, personal access to cutting-edge dairy science and the people behind the breakthroughs. Subscribe to Dairy Science Weekly to make sure you never miss any ADSA Annual Meeting or Discover Conference news, and look out for the 2025 Annual Meeting call for abstracts coming in fall 2024!