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Story: Nicole Weidner

Do you steam or soak your horse’s hay? If you don’t, you probably know someone that does. Soaking and steaming hay are two commonly used methods for managing hay, especially for horses with certain health conditions, like insulin resistance or non-infectious respiratory disease. Despite how common the practices may be, there remains little Canadian research in this area. A team of researchers based at the University of Guelph are now working on tackling this problem in a study funded by Equine Guelph that will address essential questions about the effects of these hay treatments, and provide much needed answers for horse owners and veterinarians alike.

The full research team includes: Tiana G. Owens, Madeline Barnes, Vanessa Gargano, Wilfredo D. Mansilla, Katrina Merkies and Anna K. Shoveller. Owens, a graduate student at the University of Guelph, provided Equine Guelph staff with an overview of the study design, the opportunity to see some of the research in progress, and an update on the preliminary results.

The first arm of the study addresses the nutrient content of the hay. Many horse owners in Ontario steam or soak hay to reduce its non-structural carbohydrate (NCS), including water soluble carbohydrates (WSCs), as a high dietary intake of these carbohydrates can be detrimental to some horses. However, these practices are based on research that has been done mainly in the United Kingdom. Since the United Kingdom hay has a different composition than Ontario hay, scientists here needed to know if the same results would be found when using Ontario hay. To do this, researchers collected samples from hay before and after steaming or soaking, and analyzed the nutrient content of the samples. Owens explains, “Soaking in particular was expected to lower NSC/WSC the most. Steaming has been noted to affect some nutrients in comparison to dry hay but not to the extent that soaking does, hence soaking is the treatment recommended by veterinarians to reduce NSC/WSC of certain hays when feeding horses with insulin-resistance issues.”

The second arm of the study extends the nutrient content work discussed above, where soaking and steaming hay have been shown to have different effects on the WSC content of hay. Certain types of WSC, like simple sugars, can quickly affect your horse’s blood sugar concentrations, because of how quickly they are absorbed from the digestive system. Since the scientists expected that the soaked, steamed, and dry hays would have different amounts of WSC, they wanted to see if feeding the different hay treatments to horses would have a different effect on horses’ blood sugar responses. To do this, researchers teamed up with a local racing stable, fed racehorses either soaked, steamed or dry hay, and tested their blood for several hours afterwards to monitor their blood sugar response (also known as the glycaemic response).

The third arm of the study is one that horse owners with picky eaters in their paddocks will be able to appreciate. This arm addresses the behavioural aspects of the research, by investigating whether horses have a preference for steamed, soaked or dry hay. If soaking or steaming changes the nutrient content of hay, then it’s possible the taste of the hay will also be changed. Furthermore, the “mouth-feel” of the hay may be different with different moisture contents. To do this, researchers collaborated with the same local racing stable. Horses were stalled, and hay bags containing the different hay treatments were placed into each stall. The horse’s behaviour (e.g. how much time was spent investigating and eating at each bag), and the hay intakes, were recorded.

The data for the study has been collected, and researchers are currently working on analysis. Owens provided an update on the findings so far: “Our preliminary results suggest that, as expected, soaking hay significantly reduced WSC while steaming conserved WSC content. Since athletes have good insulin sensitivity, the racehorses used in this study were able to maintain tight control over their blood sugar levels regardless of the different carbohydrate levels in the hay, indicating this particular perceived benefit of soaking hay is not applicable to these athletic performers. This information, in combination with the knowledge of other nutrients lost when soaking hay should make racehorse owners reconsider the option of steaming their hay in order to better maintain its nutritional integrity. In addition, these horses appeared to prefer steamed hay equally to their normal dry hay, while the soaked hay was a less favoured choice.”

The final results of this study will give horse owners, veterinarians and equine nutritionists insight into how soaking or steaming may affect several factors associated with horse health, and will help build a better evidence base for those making decisions about hay feeding.

Interested in learning more about the nutrient content of your hay and what implications that might have for your horse’s health? Check out Equine Guelph’s upcoming Equine Nutrition course. Make sure to stay tuned with Equine Guelph for updates about this exciting research!