What does the research say about hay soaking?
Surveys suggest that around 40% of horse owners soak their hay before feeding it, either to try to reduce starch and sugar content or to reduce dustiness. BUT hay soaking may not actually achieve either of those things!
Soaking hay for 12 hours in cold water may only reduce the combined starch and sugar content by 1-5%, this can be increased by up to 10% when warm water is used. So in reality on yards, soaking hay may have very little effect on the sugar content. If your hay has a high starch and sugar content it could still be well above maximum level recommended for feeding to laminitics – 10%.
What about reducing dust?
Dust may be leaf breakage (usually harmless) or moulds and spores (found to some level in all hay but can cause respiratory disease if present at high levels). If your hay is contaminated with a high level of moulds and spores, soaking it will only stick these to the hay, not remove them. Your horse can still breathe them in and, even worse, soaking actually increases the amount of bacteria and fungi present within the hay.
What should you do instead?
There are several commercial haylage growers producing timothy haylage that reliably has a starch and sugar content of less than 10%. This is my go to forage source for horses and ponies prone to laminitis or weight gain. Examples include Yeoman, Devon and Horsehage timothy haylages.
Steaming hay using a commercial steamer is the only way proven to reduce bacterial and mould contamination and improve its safety for respiratory health. Personally, my favourite is the Haygain system as they have plenty of research on the effectiveness of their steamers. Many of the commercial haylages mentioned above are also lower in some types of contaminants than most hay, although there is significant variation between bales.
If you want to be sure that your hay or haylage is suitable for your horse then I recommend getting it tested. Equicare provides a forage analysis service that will tell you how clean your forage is and the exact nutritional breakdown.
Take home message
Soaking hay is almost never effective or necessary in my opinion – using either a commercial haylage appropriate for your horse or a hay steamer is better for your horse’s health, and a lot easier!