Moderate Dietary Carbohydrate Improves and High Dietary Fat Impairs Glucose Tolerance in Aged Thoroughbred Geldings

Low-carbohydrate diets are often recommended for horses with metabolic syndrome and high-fat diets are useful for managing horses suffering from RER and PSSM. It is questionable whether these types of diets are appropriate for normal, non-obese horses. This study was conducted to determine whether a moderate daily intake of carbohydrate from oats or a high level of fat intake from vegetable oil would affect glucose tolerance as measured by an intravenous glucose tolerance test.

A moderate intake of carbohydrate improved glucose clearance during the intravenous glucose tolerance test compared to an all-hay or high-fat diet. Blood glucose concentration returned to baseline in 126 ± 25.8 minutes with an oat-based diet (31% of digestible energy supplied by nonstructural carbohydrates) compared to 216.7 ± 23.5 minutes for the oil-based diet (30% of digestible energy supplied by soybean oil). The difference in return to baseline concentration was statistically significant.

The oat-based diet (31% of digestible energy supplied by nonstructural carbohydrates) is characteristic of most concentrate based feeds fed to horses. The alfalfa and soybean oil diet (30% of digestible energy supplied by soybean oil) had a much higher proportion of calories supplied by fat than typical equine rations. In other species, experimental diets high in fat have been used as an experimental model to produce glucose intolerance. This study demonstrated that a high-fat diet can produce the same effects in horses.

Pagan JD, Waldridge BM, Lange J, Brown-Douglas CG and Huntington PJ (2012). Moderate Dietary Carbohydrate Improves and High Dietary Fat Impairs Glucose Tolerance in Aged Thoroughbred Geldings. Proceedings of the Australasian Equine Science Symposium 4: 20

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