Grasses and hays high in water-soluble carbohydrates (WSC) can spell disaster for horses with laminitis or insulin resistance (IR). Some veterinarians and nutritionists suggest soaking hay to reduce the amount of WSC in the hay (because water-soluble means these simple sugars dissolve in water), but how much WSC content does soaking actually reduce? According to one team of researchers, it varies depending on how long the hay is submerged.

High WSC levels markedly affect blood-insulin responses in horses and often cause an exaggerated response in laminitic or IR horses. Exaggerated insulin responses can lead to potentially life-threatening bouts of laminitis.

Led by Annette Longland, BSc, PhD, DIC, of Equine and Livestock Nutrition Services in Wales, U.K., a group of researchers recently set out to test the effects of soaking on the WSC and crude protein (CP, to see how much protein was leached during hay soaking) of nine different hays from England and Wales.

The research team completely submerged two kilograms of the mixed species meadow or ryegrass hays either compacted in the flakes or shaken loose of the flake in large plastic tubs filled with 24 liters of 8°C (46°F) tap water. Hays were soaked for 20-minute, 40-minute, three-hour, and 16-hour periods. The researchers then dried the hays in an oven before analyzing them chemically