Q: I soak my horse’s hay to reduce sugar levels because he has equine metabolic syndrome (EMS). Does soaking also remove important nutrients I need to replace?

A: Soaking hay can be a great management tactic for horses with EMS by removing some water-soluble carbohydrates (WSC). However, soaking also leaches other nutrients, making it important to evaluate the overall diet.  

Soaking EMS Horses’ Hay

For EMS horses, soak hay 30 minutes in warm water or one hour in cold water for best results. Longer soaking increases nutrient loss and, in warm weather, can raise the risk of microbial contamination such as mold.

Fully submerge the hay, keep it out of direct sunlight, drain it thoroughly, and feed it to the horse immediately.

Filling Nutritional Gaps in Your EMS Horse’s Diet

Hay alone rarely meets a horse’s vitamin and mineral requirements, whether it’s soaked or not. Depending on hay quality, your horse might also need additional protein.

A hay analysis can help determine next steps. Most adult horses do well on hay containing 10-12% crude protein (CP). If you have a growing horse, or a horse in heavy work, he will need more CP. If your hay provides adequate protein for your horse, you can rely on a vitamin/mineral supplement to fill the nutritional gaps in the hay for your metabolic horse.

Safely Feeding a Ration Balancer

If your EMS horse needs a protein-fortified ration balancer to meet his nutritional requirements in combination with the hay, be sure each meal does not exceed 0.1 g nonstructural carbohydrates (NSC) per kilogram body weight (BW).

Here is an example calculation:

• NSC content of the ration balancer is 13% on a dry matter (DM) basis
• Multiply the NSC content by the feeding rate:
  • (0.13 NSC) x (454 g) = 59.02 g NSC
• Divide NSC in grams by the horse’s body weight:
  • 59.02 g NSC/500 kg BW = 0.12 g NSC/kg BW

The amount exceeds 0.1 g NSC/kg BW, which means you’d divide the ration balancer amount this EMS horse needs into two meals. The result, a NSC content of 0.06 g NSC/kg BW/meal, is within the recommended safe guidelines.

Take-Home Message

Hay alone will not meet a horse’s nutrient requirements, and soaking hay to reduce sugars does leach additional nutrients. To ensure your horse does not develop nutritional deficiencies, test your hay to determine the nutritional content and choose either a vitamin/mineral premix or protein-fortified ration balancer to meet his nutritional needs.