METABOLIC RESPONSES OF CHRONICALLY STARVED HORSES TO REFEEDING WITH 3ISOENERGETIC DIETS

Objective-To examine metabolic responses of chronically starved horses to refeeding with 3 isoenergetic diets. Design-Uncontrolled clinical trial. Animals-22 mature mixed-breed horses that were emaciated but ot herwise clinically normal. Procedure-Horses were fed 1 of 3 diets: alf alfa hay, oat hay, or a combination diet of half oat hay and half comm ercially prepared ration. Digestible energy of diets was gradually inc reased throughout the refeeding period. One pre-and 4 postprandial blo od samples were obtained daily, and analyses included RBC count, Hct, and determination of hemoglobin, glucose, insulin, free fatty acid, to tal bilirubin, 2,3-diphosphoglyceric acid, phosphorus, magnesium, calc ium, sodium, and potassium concentrations. Body weight, fecal output, and feed and water consumption were measured and recorded daily. Repea ted-measures ANOVA was used to examine dietary and temporal (day) effe cts of the 3 dietary regimens during 10-day trials. Results-19 horses survived. Three horses (2 fed alfalfa diet, 1 fed combination diet) di ed of metabolic or gastrointestinal problems. Increasing temporal effe cts in serum concentrations of glucose, insulin, magnesium, calcium, a nd sodium; decreasing temporal effects in serum concentrations of free fatty acid, 2,3-diphosphoglyceric acid, and phosphorus; and dietary e ffects in serum concentrations of glucose, insulin, magnesium, and pot assium were detected in the 19 surviving horses. Serum phosphorus and free fatty acid concentrations decreased dramatically during the first 5 days of refeeding with all 3 diets. Serum magnesium concentrations increased in horses fed the alfalfa hay diet, whereas improvement was not evident in horses fed oat hay or combination diets. Horses receivi ng the alfalfa and oar hay diets had lower postprandial glucose and in sulin concentrations than horses receiving the combination diet. Horse s fed oat hay alone ate 92% of feed offered, compared with 98% feed co nsumption for horses fed alfalfa hay or combination diets. Clinical Im plications-Clinically normal emaciated horses can be successfully reha bilitated by gradual refeeding with a high forage diet.