Ketosis: The Hidden Challenge Affecting Dairy Herd Performance

When it comes to dairy herd health, some of the biggest threats are the hardest to spot. Ketosis is a prime example: a metabolic challenge that quietly chips away at productivity, fertility, and profitability, often without any obvious clinical signs. In fact, ketosis, also called hyperketonemia, affects approximately 400,000 cows in early lactation every year in Canada (4 in 10 cows). Of those cases, as much as 95% are subclinical, i.e. invisible to the naked eye.

Why Ketosis Matters and What Puts Cows at Risk

Most fresh cows with elevated ketones will look fairly normal, but under the surface, the disease will eventually have an impact on milk yield, breeding success, and health. If left unchecked, this “silent thief” can cost producers dearly, not just in lost milk, but in higher risk of other diseases like displaced abomasum, higher culling rates in early lactation, delayed conception, and increased vet bills. Each case of hyperketonemia can remove up to $400 from your bottom line, making early action critical for herd profitability.

Ketosis typically develops early in lactation, when energy demand for milk production soars but feed intake hasn’t caught up. Cows then start mobilizing body fat for fuel, and some of that mobilized fat will be transformed by the liver into ketones which will build up in the blood. While some weight loss is normal, excessive weight loss and poor feed intakes often lead to ketosis. Certain risk factors for ketosis have been identified: high-energy dry cow rations, cows that are over-conditioned at calving, long dry periods, carrying twins, inconsistent bunk management, or limited access to feed and water. Crowded or uncomfortable housing also tips the balance, reducing intake when cows need it most.

Invisible Losses and the Power of Monitoring

With 95% of ketosis cases being subclinical, relying on visible symptoms is a losing battle as it only shows the tip of the iceberg. Subclinical ketosis, where cows appear normal but have elevated ketones, is far more common than the clinical form. These invisible cases can spiral into major issues like displaced abomasum, metritis, and poor conception rates.

That’s why routine testing in the first two to three weeks after calving makes such a difference. It isn’t just about catching sick cows; it’s about ensuring your transition program is working. At the herd level, testing gives a clear snapshot of how cows are adapting and whether your nutrition and management strategies are on target. At the individual level, frequent monitoring of the fresh cows allows you to find and treat cows that are positive to the ketone test, allowing you to minimize your losses.

Prevention Begins Before Calving

The best defense against ketosis starts in the dry period. Keep dry cow diets balanced, with enough energy for maintenance and fetal growth, but not so much that cows gain excess weight. To avoid overfeeding energy, you may need to dilute the dry cow ration by adding chopped straw or mature forages. Comfortable housing, ample bunk space, and access to fresh, clean water are all essential. When cows are crowded or stressed, their feed intake may suffer, opening the door to metabolic issues. Consistent routines, clean feed, and a calm environment make a real difference.

Keys to a Strong Start and Lasting Success

A smooth transition sets the foundation for a productive lactation. Prevention means getting the fundamentals right: moderate body condition, balanced rations, comfortable facilities, and proactive monitoring. Test all fresh cows within the first two to three weeks post-calving, use those results to spot at-risk cows, and act quickly on elevated ketones. Pair routine observation with regular testing and adjust your transition approach as needed.

Tackling ketosis takes a team. Work closely with your veterinarian and your nutritionist to tailor a transition plan for your herd. Your Elanco representative is also a valuable partner, offering expertise, research insights, and practical solutions to keep your cows and your bottom line on track.

With the right management and support, ketosis doesn’t have to be a recurring problem. By staying alert to the hidden risks and acting early, you can protect herd health, improve performance, and prevent hundreds of dollars in lost profit, one successful transition at a time.