Q: My Thoroughbred gelding tends to lose weight during the winter months (he drops a full body condition score), but during the summer he maintains a body condition score of 5 easily. What can I do during the warmer months to help prevent this weight loss once fall and winter arrive?

A: Many horses drop weight during the winter, but proactive management can help your horse maintain optimal condition year-round. Planning ahead—before the pounds slip away—sets the stage for success.

If your horse maintains a body condition score (BCS) of 5 in the summer but drops weight in colder months, start by calculating his summer calorie intake. This number gives you a baseline to guide winter feeding adjustments.

Seasonal Forage Changes

Access to high-quality pasture during summer and hay-only diets in winter often lead to calorie discrepancies that contribute to seasonal weight loss. Even if forage type stays consistent season to season, switching to new hay introduces nutritional variables.

Hay’s calorie content can shift significantly based on plant maturity and harvest conditions. This subtle change can create major weight fluctuations.

To reduce seasonal weight swings, aim to keep your horse’s calorie intake consistent year-round. In colder months modestly increase those calories to help offset greater energy needs.

Measuring Calorie Content

Testing your hay remains the most accurate way to measure caloric content; without testing, you risk feeding lower-calorie hay than intended. Each batch varies, and analysis provides critical data on energy levels. For instance, hay’s caloric content can range between 1.5 and 2.5 megacalories (Mcal) per kilogram—a major difference when feeding daily rations. By tracking how many calories support a healthy body condition in your horse, you can fine-tune winter feeding strategies.

Adding Supplemental Calories

Beyond testing your hay and monitoring your horse’s forage caloric intake, add extra calories before the weather turns. Horses that lose weight in winter often benefit from increased energy intake in late summer or early fall, especially if pasture forage quality begins to wane due to drought or getting colder, respectively.

Bringing a horse into winter with a BCS of 5.5—or even up to 6—can help prevent drops below a healthy 4 during colder months. Introduce energy-dense feeds such as oils or fortified fat supplements. Fiber-rich options, including beet pulp or hay cubes, can also support calorie intake without relying heavily on grain (concentrates).

Take-Home Message

Nutritional discrepancies due to forage changes—from pasture to hay or between hay batches—often go unnoticed until horses begin to lose condition. These transitions can significantly impact total calorie intake. Testing hay and consulting with an equine nutritionist can help you understand and meet your horse’s caloric needs. Before temperatures drop, consider adding supplemental calories such as fat or digestible fiber to support your horse through the season.