Glucose and insulin responses to delayed rate of intake of concentrate meals by horses

Pronounced changes in postprandial blood glucose and insulin concentrations in horses may be problematic for horses with metabolic disorders. Research has identified specific grains and processing methods for attenuating glycemic response to concentrate meals, and other methods of manipulating concentrate meals are needed when these are not available to horse caretakers. Controlling rate of intake of a concentrate meal through portioning may be one method that could attenuate glycemic response. In 2 experiments, a serial blood draw was performed in conjunction with offering of a concentrate meal to follow postprandial changes in plasma glucose and insulin. Meals were portioned into smaller allotments and offered at 15-min increments. In Exp. 1, 8 horses received 4 Mcal of DE from oats or sweet feed divided into 1, 2, 3, or 4 portions. Glucose and insulin area-under-the-curve concentrations and peak concentration values were not different between feed types or among portioning treatments (P > 0.05). In Exp. 2, the equivalent of 8 Mcal of DE divided into 1, 3, or 5 portions was offered to 6 horses fed a conventional sweet feed or a sweet feed with grains processed to minimize glycemic response. Horses consuming conventional sweet feed had greater glucose and insulin area-under-the-curve concentrations (P < 0.05) that may have been due to differences in total nonstructural carbohydrate content of the 2 feedstuffs. Portioning of the concentrate meal had no effect (P > 0.05) on postprandial glucose and insulin responses in Exp. 2. Delaying the rate of intake of a concentrate meal under these conditions did not alter glycemic response.