title: Effects of various diets on gastric tone in the proximal portion of the stomach of horses.
abstract: OBJECTIVE
  To assess gastric tone in the proximal portion of the stomach in horses during and after ingestion of 4 diets (2 diets of grain and 2 diets of hay).
  
  
  METHODS
  6 adult horses.
  
  
  METHODS
  A polyester bag with a volume of approximately 1,600 ml was inserted through a gastric cannula into the proximal portion of the stomach of each horse. Internal pressure of the bag was maintained at 2 mm Hg by use of an electronic barostat, and changes in bag volume were recorded before, during, and after horses consumed diets of grain or hay. Each horse was fed 0.5 and 1.0 g of grain/kg and 0.5 and 1.0 g of hay/kg. Changes in bag volume measured by use of the barostat were indirectly related to changes in tone of the gastric wall.
  
  
  RESULTS
  Food intake caused a distinctly significant biphasic increase in volume. The first phase was during active ingestion, which was followed shortly by a second, more prolonged postprandial phase. The ingestion-related phase of the response to intake of a diet of 1 g of hay/kg was significantly greater than that for the other diets.
  
  
  CONCLUSIONS
  ingestion of a solid meal induces a biphasic relaxation response in the proximal portion of the stomach of horses. Magnitude of the ingestion-related phase may be determined by size of the meal.
authors.affiliation: Island Whirl Equine Colic Research Laboratory, College of Veterinary Medicine, University of Florida, Gainesville 32610-0136, USA.
authors.forename: Mireia
authors.initials: M
authors.lastname: Lorenzo-Figueras
authors.forename: Galin
authors.initials: G
authors.lastname: Jones
authors.forename: Alfred M
authors.initials: AM
authors.lastname: Merritt
mesh_terms: D000818:Animals; D004032:Diet; D005260:Female; D005769:Gastrointestinal Motility / Q000502:physiology; D006736:Horses / Q000502:physiology*; D008297:Male; D009129:Muscle Tonus / Q000502:physiology*; D009130:Muscle, Smooth / Q000502:physiology*; D013270:Stomach / Q000502:physiology*; D013997:Time Factors