Much as many owners of IR/EMS horses depend on soaking hay being a crucial lifeline for their horse, there's now evidence out there showing a significantly increased bacterial risk to the gut system when soaking.

I used to steam our Kelso’s hay day-in, day-out, because of his chronic respiration - it wasn’t about the grass sugars for him, it was all about the airborne respirable dust for him, full of allergenic bacteria, moulds, fungi and yeast. However, there's now evidence out there showing that steaming hay to reduce the grass sugars may also be infinitely healthier for our metabolic horses as well.

There are some pretty nifty benefits to steaming that we already know - unlike soaking, steaming conserves the minerals, trace elements and crude protein, whereas soaking hay has been reported to cause significant losses of minerals and soluble protein.

Steaming also uses far less water and is much less laborious - lugging heavy soaked haynets is a right royal pain – breaks your back and you get soaked jeans in the process. With Kelso's steamed hay I simply pitchforked it straight from my (home-made) steamer into his stable.

Best of all though, high temperature steaming has a major advantage over soaking: it kills bacteria, mould, fungi and yeast, producing hygienically clean forage for our horse.

Now for the grim stuff

Soaking has always been the traditional method for the metabolic horse to reduce the nutritional value - some would say it's life-saving, but – there are studies out there (Moore-Colyer et al 2015, Wyss and Pradervand, 2016) that show soaking increases the bacterial content of hay, “compromising the hygienic quality and raising the bacterial concentration above the upper safe limit of 20µg/g”, which could lead to colic/autoimmune responses.

Worse still, the post-soak liquor is a strong pollutant - biological oxygen demand (BOD) of nine times that of raw sewage (Warr and Petch 1992). Hence why you can’t pour it down storm drains. We've all seen what that water looks like after a long soak, never mind the raised bacterial concentration. No surprise that some horses really struggle to eat soaked hay.

Now to the WSC stats - that same study measured WSC (Water-soluble carbohydrates -- measures simple sugars and fructan levels. Simple sugars are digested in the foregut and raise insulin levels) in several different steamed UK hays – average losses were variable between 2.3% - 18%, compared to soaking variables starting less at 2%, with the higher values impossible to determine due to the variables in soaking time. A 16-hr soak recorded losses of 54%, which for owners of EMS horses is appealing, but ... with leaky gut now considered an epidemic, is the increased pro-inflammatory pathogen bacterial risk worth it?

Either way, these numbers show that unless you're going for the long soak, which will mean the increased bacterial risk, neither soaking nor steaming are going to reduce the WSC hay content significantly. For sure, if you're concerned about the leaky-gut risk for the EMS horse, steaming is certainly a consideration for the Bigger Picture. That said, for the seriously hardcore carb-intolerant metabolic … that same study suggests a soaking-then-steaming combo, or at the very least a darned-good hose down to wash out as much of the soak-water as possible.

How to make a home-made steamer

There are probably tons of ways on YouTube, but this is what I personally did. Take 1 wheelie bin (yes I shamelessly robbed our home one), a grid/grill thingy from a BBQ to wedge inside the bin a good 8"-plus off the bottom, and a £20 wallpaper steamer from B&Q or similar. These wallpaper steamers are brilliant - they're like an oblong plastic 'kettle' where you add in the water, with a long bendy hose that emits the steam. Obvious I know but you'll need an electricity supply at the yard - I only say this as some yards don't have electricity.

(Got the husband to) Drill a hole at the bottom of the bin, big enough to fit the hose through and under where the grid will be. Fill bin with hay - or haynets if you prefer - and close lid, fill steamer with water, switch on and let the cycle finish - you should get around 40mins to an hour.

When done, wheel your bin to where you want the hay - in my case Kelso's stable, where I tipped the bin on its side, flipped the lid open and forked the hay straight out into a big pile for him. So easy.

References:

https://www.researchgate.net/.../268875565_The_Effect_of...

https://pubmed.ncbi.nlm.nih.gov/25426729/

Stockdale, C and Moore-Colyer, M.J.S (2010) Steaming hay for horses: The effect of three different treatments on the respirable particle numbers in hay treated in the Haygain steamer.

European Workshop for Equine Nutrition, Cirencester, Sept 2010. The Impact of nutrition on the health and welfare of horses.

EAAP publication No. 128. Ed Ellis, A., Longland, A.C., Coenen, M and Miraglia, N. p136-1382. Moore-Colyer, M.J.S and Fillery, B.G. (2012) The Effect of three different treatments on the respirable particle content, total viable count and mould concentrations in hay for horses.

6th European Workshop for Equine Nutrition, Lisbon, Portugal, June. 101- 106.3. Moore-Colyer, M.J.S. Taylor, J. and James, R (2015). The effect of steaming and soaking on the respirable particle, bacteria, mould and nutrient content in hay for horses.

Journal of Equine Veterinary Science. Aug 20154. Moore-Colyer, M.J.S. Taylor, J. and James, R (2015). The effect of steaming and soaking on the respirable particle, bacteria, mould and nutrient content in hay for horses.

Journal of Equine Veterinary Science. Aug 20155. Wyss, U. and Pradervand, N. (2016) Steaming or Soaking. A

groscope Science. Nr 32 p32-336. Moore-Colyer, M.J.S. and Payne, V. (2012) Palatability and ingestion behaviour of 6 polo ponies offered a choice of dry, soaked and steamed hay for 1 hour on three separate occasions.

Advances in Animal Biosciences. Healthy Food from Healthy Animals. Vol 3 part 1. 1277.

Brown, E., Tracey, S and Gowers, I. (2013) An investigation to determine the palatability of steamed hay, dry hay and haylage.

Proceedings of British Society of Animal Science Conference, Nottingham April 2013. p 1048. James, R. and Moore-Colyer, M.J.S. (2013) Hay for horses: The nutrient content of hay before and after steam treatment in a commercial hay steamer.

Proceedings of British Society of Animal Science Conference, Nottingham April 2013.9. Moore-Colyer, M.J.S. Taylor, J. and James, R (2015). The effect of steaming and soaking on the respirable particle, bacteria, mould and nutrient content in hay for horses.

Journal of Equine Veterinary Science. Aug 201510. Warr EM, Petch JL (1992) Effects of soaking hay on its nutritional quality. Eq.Vet.Edu. 5:169–171.

Brown, James S et al. “Thoracic and Respirable Particle Definitions for Human Health Risk Assessment.” Particle and Fibre Toxicology 10 (2013): 12. PMC. Web. 29 Nov. 2017.

National Research Council. Nutrient requirements for Horses. 6th rev. ed. Washington DC. USA: National Academic Press; 2007.

Moore-Colyer MJS, Lumbis K, Longland AC, Harris PA. (2014).The effect of five different wetting treatments on the water soluble carbohydrate content and microbial concentration in hay for horses.

Plos One. Moore-Colyer, M.J.S. Taylor, J. and James, R (2015). The effect of steaming and soaking on the respirable particle, bacteria, mould and nutrient content in hay for horses.

Journal of Equine Veterinary Science. Aug 2015 Warr, E., and Petch, J (1992) Effects of soaking hay on its nutritional quality. Equine Veterinary Education 5: 169-171

Wyss, U. and Pradervand, N. (2016) Steaming or Soaking. Agroscope Science. Nr 32 p32-33