Six important British-based studies relating to laminitis and nutrition in horses were among those presented at the recent Equine Science Symposium (ESS) in Asheville, North Carolina, in the US.
The Equine Science Society is a US-based international body promoting quality research on equine nutrition and physiology. It holds a symposium every other year and cooperates with other organisations with similar interests.
Through its collaborators, six research papers were presented at the symposium this week by the Waltham Equine Studies Group, which investigates the role of nutrition in the health, welfare, behaviour and performance of horses.
“While our understanding of the science behind equine conditions such as laminitis, equine metabolic syndrome, insulin dysregulation and senior nutrition continues to grow, there is still much that we don’t know,” said Clare Barfoot RNutr, the research and development manager at feed manufacturer Spillers. The science behind Spillers is provided by the Equine Studies Group at the Waltham Centre for Pet Nutrition.
“As partners in care we strive to lead, support and communicate research to continually expand our knowledge and improve horse health worldwide. We are extremely proud to present some of our important recent work at ESS this year.”
Three associated with potential risk factors for laminitis and three associated with other aspects of nutrition were presented by Waltham through its collaborators:
Endocrinopathic laminitis is considered a major form of laminitis, specifically insulin dysregulation (ID) associated with the Equine Metabolic Syndrome (EMS). The study Insulin Dysregulated and Healthy Horses’ Seasonal Insulin Responses to the Oral Sugar Test documented seasonal insulin changes over a two-year period, with the lowest insulin values being found in the autumn. The results suggest a potential need for establishing seasonal reference ranges for diagnosing insulin dysregulation via the oral sugar test.1
Insulin dysregulation (ID) is associated with an increased risk of laminitis. The oral sugar test (OST) has been suggested as a practical diagnostic tool for ID determination. Recently, research in the UK showed that increasing the OST dose better differentiated between ponies with and without a history of laminitis. The study Effect on the insulin response to varying doses of corn syrup to the Oral sugar test (OST) looked at the applicability of this test for horses and found that some ID horses could potentially be misdiagnosed because their low dose OST value fell under the currently recommended cut-off level.2
Recently it has been suggested that the main feature of equine metabolic syndrome (EMS) is insulin dysregulation (ID) associated with an increased risk of laminitis, with or without other metabolic alterations and/or obesity. The study Relationship between insulin dysregulation and morphometric neck measurements in the non-obese stock-type horse showed that reassuringly, ID was not prevalent in most non-obese stock-type horses but an increase in neck crest height, even in non-obese stock-type horses, may indicate a greater risk of ID.3
Vitamin E is an essential antioxidant and key component in equine diets. The study Cytokine and oxidative stress response to vitamin E supplementation in exercising horses suggested that feeding higher levels of the more bioactive natural vitamin E may have beneficial effects for the equine athlete.4
It is widely accepted that extruding feed increases digestibility, however, recent work has reported reduced digestibility. The study Digestibility and postprandial response according to processing method and meal time of day showed no significant beneficial or adverse effect of feeding the same feed ingredients, processed either by extrusion or pelleting on digestibility.5
Prebiotics may help increase digestibility through modification of the hindgut microbiota and improving overall host health in senior horses. The study Are prebiotics beneficial for digestion in mature (adult) and senior horses? found no differences between apparent digestibility in mature and senior groups when fed short-chain fructooligosaccharides (scFOS) in a ration balancer. Interestingly, on un-supplemented diets the mature group showed greater digestibility when fed 1.5% bodyweight per day of hay compared to the senior group. A previous study had shown no effect of age on digestibility when groups were fed a higher level of fibre. This indicates that dietary prebiotic supplementation may help mitigate some decreases in digestibility experienced by seniors under certain conditions.6
Spillers has several other nutrition related studies in progress around the world and is also currently recruiting a student for a PhD project looking at the microbiome and its association with laminitis risk.
1. Macon, E. L., P. A. Harris, V. D. Barker, S. Elzinga, A. A. Adams. (2019). Insulin dysregulation and healthy horses’ seasonal insulin responses to the oral sugar test. Journal of Equine Veterinary Science 76 p38.
2. Macon, E. L., P. A. Harris, A. Herbst, A. A. Adams. (2019). Effect on the insulin response to varying doses of corn syrup to the oral sugar test (OST). J Equine Veterinary Science 76; p42-43.
3. Heaton, C. P., C. A. Cavinder, E. N. McClure, T. Smith, P. Harris, N. Liburt, and A. Krotky. 2019. Relationship between insulin dysregulation and morphometric neck measurements in the non-obese stock-type horse. 26th Equine Science Society Symposium, Asheville, NC, June 3-6, 2019; p181.
4. Fagan MM, Adams A, Harris P, Krotky A, Duberstein KJ. Cytokine and oxidative stress response to vitamin E supplementation in exercising horses. J Equine Veterinary Science 76: p48-9.
5. Ely K., P. Harris, K. Kaufman, N. Liburt, A. Krotky, B. McIntosh (2019). Digestibility and postprandial response according to processing method and meal time of day. J Equine Vet Sci 76; p67.
6. Heaton, C. P., C. A. Cavinder, H. Paz, B. J. Rude, T. Smith, E. Memili, P. Harris, N. Liburt, and A. Krotky. 2019. Are prebiotics beneficial for digestion in mature and senior horses? J. Equine Vet. Sci. p106.