Feed Type And Intake Affects Glycemic Response In Thoroughbred Horses

Pagan, J.D., P.A. Harris, M.A.P. Kennedy, N. Davidson and K.E. Hoekstra. 1999. Feed type and intake affects glycemic response in Thoroughbred horses. In: Proc. 16th Equine Nutr. and Physiol. Soc. Symp. pp. 149-150.

A 6 x 6 Latin square design experiment was conducted to determine glycemic response in horses fed six different feeds at 3 different levels of intake. Six Thoroughbred geldings were fed mixed grass hay and one of six diets: cracked corn, whole oats, sweet feed (45% cracked corn, 45% whole oats, and 10% molasses), sweet feed + 10% corn oil, alfalfa forage, or a low starch, high fermentable fiber mix (25% rice bran, 25% soy hulls, 25% wheat bran, and 25% soaked beet pulp). Horses were randomly assigned low (.75 kg), medium (1.5 kg), or high (2.5 kg) intake levels at each feeding during six 3-day test periods. Diets were fed at medium intake (1.5 kg/feeding) twice each day and each horse received 5.45 kg hay per day during transitions between test periods, during which time treatments were altered for the subsequent period. Horses were given access to free exercise on pasture during the day, although they were not allowed to graze. On test days, morning feeding levels equaled 750, 1,500, or 2,500 g of the treatment diets in every case except sweet feed + corn oil. Horses on this diet received 750, 1,500, or 2,500 g of sweet feed with an additional 75, 150, or 250 g corn oil, respectively. Blood samples were taken prior to the morning feeding on test days to determine baseline glucose values and at 30-min intervals following feeding until glucose levels returned to or dropped below baseline for 120 min.Mean glucose (mg/dl) was highest for sweet feed, whole oats, and the low starch, high fiber mix and lowest for the alfalfa diet. More research is required to determine the relevance of glycemic response in predicting the effects of different feed ingredients on a horse’s performance or behavior.

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