Meal-induced gastric relaxation and emptying in horses after ingestion of high-fat versus high-carbohydrate diets

Abstract

Objective - To evaluate the effect of ingestion of a high-carbohydrate versus a high-fat meal on relaxation of the proximal portion of the stomach and subsequent gastric emptying in horses. Animals - 6 healthy adult horses. Procedure - The study consisted of 2 phases. In phase I, horses were offered a high-fat (8% fat) or a high-carbohydrate (3% fat) pelleted meal (0.5 g/kg) of identical volume, caloric density, and protein content. In phase II, meals consisted of a commercial sweet feed meal (0.5 g/kg) or this meal supplemented with corn oil (12.3% fat) or an isocaloric amount of glucose (2.9% fat). Proximal gastric tone was measured by variations in volume of an intragastric bag introduced through a gastric cannula and maintained with a constant internal pressure by an electronic barostat. Rate of gastric emptying was measured simultaneously with the 13C-octanoic acid breath test. Interaction between both techniques was studied in additional experiments. Results - Meals with higher carbohydrate content induced a significantly more prolonged receptive relaxation of the proximal portion of the stomach than those with higher fat content, but the accommodation response was similar. Labeling the meals with the breath test marker influenced the accommodation response measured by the barostat. Gastric emptying rates were not significantly different between meals, although those high in carbohydrate initially emptied more slowly. Conclusions and clinical relevance - In horses, in contrast to most species, dietary fat supplementation may not have a profound effect on gastric motility.