New research, conducted by the WALTHAM-initiated Laminitis Consortium, has raised questions over the assumption that soaking hay will make it safe to feed to laminitis-prone horses and ponies¹. 

The Laminitis Consortium comprises world-leading equine veterinary, nutrition and research experts interested in collaborating on the important topic of laminitis. It includes the authors of this work: Dr Pat Harris of the WALTHAM^® Equine Studies Group, Clare Barfoot of Mars Horsecare UK Ltd and Dr Annette Longland of Equine Livestock and Nutrition Services (ELNS).

Over-consumption of water-soluble carbohydrates (WSC) has been associated with the onset of laminitis. It has been recommended that hay with a non-structural carbohydrate (WSC and starch) content of less than 10% should be fed to obese animals as well as those at risk of laminitis² and that hay should be soaked in water before being fed in order to reduce the WSC^3,4,5.  The study, which was completed earlier this year, examined the loss of water-soluble carbohydrates from nine different hays submerged in water for up to 16 hours.  It was presented to the biannual Equine Science Symposium in America in May 2009.

Previous studies have shown that the prolonged soaking of chopped hay in large volumes of water can result in the leaching of nutrients, including soluble carbohydrates. However, because common practice in the UK tends to involve long-stemmed hay, soaked in relatively small volumes of water over varying timescales, the Laminitis Consortium's study aimed to replicate such a practice⁶.

The nine different hay samples were analysed for WSC and then soaked in cold water. The soaked samples were subsequently analysed at four intervals of 20 minutes, 40 minutes, three hours and 16 hours.

Clare Barfoot said: "The results showed a highly variable leaching of WSC and substantially less leaching than reported previously for chopped hay soaked for 30 minutes.³

"Very few samples reached below 10% WSC, despite prolonged soaking. The concern is that this strongly suggests that soaking may not be sufficient to render some hays safe to feed to horses and ponies prone to laminitis. 

"Our current advice is that ideally you should analyse your hay before feeding it to an animal at high risk of laminitis and choose hay with the lowest WSC content you can find. Soaking hay provides an additional safeguard but should not be relied upon."

The study also highlights that if hay is soaked for extended periods, it may not meet the nutritional requirements of the animal because substantial amounts of other nutrients, protein, vitamins and minerals will also be lost ⁵. In such cases it is even more important that the horse or pony should receive a balanced supplementary feed.

The Laminitis Consortium is continuing its work in this area and hopes to be able to identify practices that will be of greater benefit to the horse owner faced with hay of unknown WSC content.

¹Longland AC Barfoot C &  Harris PA  (2009) The loss of water- soluble carbohydrate and soluble protein from nine different hays soaked in water for up to 16 hours.  J. Equine Vet Science 29 (5 ) p 383 - 384, ² Frank  N Equine Metabolic Syndrome J Equine Vet Sci 29 (5) p 259 - 267, ³Cottrell, E., Watts, K., Duarte, S. and Ralston, S. (2005). Equine Science Symposium, 2005, ⁴Kenny, D. (2007). Proceedings of the British Society of Animal Science. ⁵Warr EM, Petch JL. Equine Vet Educ 1993;5:169-171, ⁶Longland, A.C. (2009) In preparation.

PS: Whilst you're here, take a moment to see our latest job opportunities for vets.