Electrolyte Balance in Exercising Horses Fed a Control and a Fat-Supplemented Diet

Abstract

Summary Eight mature Thoroughbred horses were used in a replicated 4 x 4 Latin square experiment to verify the results of a previous study conducted in this laboratory which estimated dietary electrolyte requirements for exercising Miniature Horses, and to evaluate the effect of feeding fat on electrolyte balance. The rations contained concentrations of electrolytes as suggested from the previous study. Horses were exercised at two work loads that increased digestible energy requirements to approximately 145% and 180% of maintenance, and were fed a control diet and a fat-supplemented diet. Each period of the Latin square was 3 weeks. Mineral balance trials were conducted during the last 4 days of each period. During the balance trials, horses were housed in metabolism crates, except while exercising, for total urine and fecal collections. Sweat loss was quantified and sweat samples were collected. Feed, water, fecal, urine, and sweat samples were used to determine electrolyte balances in exercising horses supplemented according to predicted needs. Sweat losses in horses in this study averaged 11.9 g/kg BW at the lowest work load and 15.6 g/kg BW at the highest work load. There were no significant differences in composition of sweat due to work load or diet. Furthermore, there was no effect on electrolyte balance due to diet. Horses were in near electrolyte balance when fed the concentrations of sodium, potassium and chloride as predicted from a previous study conducted in this laboratory. Thus, to maintain exercising horses in electrolyte balance, diets should contain (per Mcal of DE) approximately 1.3 g sodium, 3.1 g chloride and 4.5 g potassium.