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Soaking your horse’s hay

Quick facts

  • Rely on forage tests before and after soaking to decide which type of hay is best for your horse especially with a horse that has laminitis, PSSM, HYPP or COPD.

    • For these horses NSC, P and mold content are key.

  • Soaking hay for 15 to 60 minutes is a good way to manage these horses, but only soak hay if your preferred hay isn’t available.

  • Feed soaked hay right away to avoid mold growth.

  • Dispose of water in random grassy areas that horses can’t access.

Why soak hay?

Soaking hay in water is a common way to care for horses diagnosed with one of the following.

  • Laminitis

  • Polysaccharide Storage Myopathy (PSSM)

  • Hyperkalemic Periodic Paralysis (HYPP)

  • Chronic Obstructive Pulmonary Disease (COPD)

Soaking hay for 15 to 60 minutes in water reduces water soluble carbohydrates (WSC), potassium (K) and dust. Each of these elements play a role the diseases mentioned above.

  • Researchers suggest complete rations (hay, grain and supplements) should contain less than 12 and 10 percent nonstructural carbohydrates (NSC)(starches and sugars in forage) for horses with laminitis and PSSM, respectively.

  • Reynolds et al. 1997 found that horses with HYPP need complete diets less than 1 percent K.

  • Moore-Colyer 1996 found that soaking hay for 30 minutes reduced respiratory problems for horses with COPD or heaves.

Does soaking hay remove other nutrients?

Hay soaking in water inside plastic bins.
We soaked the hay for 15 minutes to 12 hours in cold and warm water.

We looked at four hay types including:

  • Budding alfalfa (AB)

  • Flowering alfalfa (AF)

  • Vegetative orchardgrass (OV)

  • Flowering orchardgrass (OF)


Authors: Jim Paulson, former Extension dairy educator, Jennifer Earing, former postdoctoral student, College of Food, Agricultural and Natural Resource Sciences, Roy Johnson, Cargill, and Sarah Ralston, DVM, Rutgers

Reviewed in 2021

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