Glycemic response to meal length in horses
Type of DegreeThesis
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Cereal grains are an ideal feedstuff for horses with high energy demands because of their high soluble carbohydrate content. However, consumption of a single meal high in soluble carbohydrates causes an immediate increase in blood glucose. This increase could be problematic for horses with certain health conditions such as insulin resistance or laminitis. Because some horses require additional energy for growth, performance, pregnancy or lactation, it becomes difficult to completely remove cereal grains from their diet. Therefore, new feeding management strategies are needed to attenuate the blood glucose response to meals high in soluble carbohydrates. The objective of this study was to assess the glycemic response to a concentrate meal based on time required to consume that meal as measured by peak plasma glucose and insulin concentrations, glucose and insulin areas under the curve, and time to peak plasma glucose and insulin. Eight mature, idle horses were used in an experiment consisting of eight 7 d periods in which treatment combinations were systematically arranged in a 2 × 4 factorial of feeds and meal portions. Horses were offered approximately 4 Mcal of oats or textured sweet feed twice daily at 0600 and 1800 h. Horses were offered their respective concentrate in 1, 2, 3, or 4 equal portions in 15 min intervals, thereby restricting rate of intake of the concentrate. Blood was collected via indwelling jugular catheters at the evening feeding on d 7 of each period, with a baseline sample collected 30 min prior to feeding (1750 h), then every 30 min post-feeding until 0000 h. Plasma glucose and insulin concentrations were determined, and resulting data were analyzed by the GLM procedure of SAS. Time to peak plasma insulin was longer (P < 0.05) for horses consuming oats, but there were no other significant differences for concentrate type, portions, or treatment interactions for glucose and insulin. A period effect (P < 0.05) was noted for peak plasma glucose and time to peak plasma glucose. There was a trend (P < 0.10) toward a period effect for glucose area under the curve, but no period effects were observed for measures of insulin. A horse effect (P < 0.05) was also noted for peak plasma glucose and insulin as well as glucose and insulin area under the curve (AUC). Glucose and insulin responses to a concentrate meal were not altered by time to consume the meal in the present study.