28 Effects of low-dose electrolyte supplementation to university horses in light to moderate exercise

Abstract

Electrolyte supplementation is a frequent practice in human and equine athletes, as exercise in hot and humid weather can exacerbate electrolyte and fluid losses. Previous equine electrolyte research has focused on supplementation of horses in heavy or very heavy workloads with limited research in horses in light to moderate workloads. The objective of this research was to determine if a low-dose electrolyte supplement would benefit university horses in light to moderate exercise during hot and humid weather, with the intention to elucidate information regarding electrolyte supplementation to other lesson programs or horse owners. The study covered 5 consecutive weekdays during mid-September in Murfreesboro, Tennessee, with record high temperatures (33 to 37°C) and humid weather. Eleven mature stock-type horses from the Middle Tennessee State University teaching and research herd were selected for the study, with 5 horses assigned to the treatment group and 6 horses assigned to the control group. Treatment horses received a low-dose oral electrolyte supplement daily for 5 d comprised of 0.07g NaCl/kg of body weight (BW) and 0.02g KCl/kg BW, and control horses received 0.09g/kg BW granulated sugar as a placebo. All horses received their normal diet of Purina Strategy concentrate and prairie grass hay. Measurementsincluded 24-h water intake, fasted blood glucose, and plasma concentrations of sodium, potassium, and chloride. Throughout the week studied, each horse was ridden daily. Riders for each horse were blinded to treatments and completed a Qualtrics survey following each ride to assess their perceptions of horse performance and willingness to work. Data were analyzed using a mixed model with repeated measures or a GLM procedure when appropriate (SAS 9.4) with significance set at P < 0.05. Rider-perceived horse fatigue (P = 0.23) and willingness (P = 0.47) were not different between treatments. Day had an effect on water consumption (P < 0.01), with average water consumption peaking at 37L on d 3 with the highest ambient temperature (37°C), while treatment did not affect water consumption (P = 0.94). Treatment did not affect horse weight (P = 0.66), or serum levels of sodium (P = 0.18), potassium (P = 0.92), and chloride (P = 0.26). Average blood glucose tended to be higher in control animals (P = 0.06), however they were receiving granulated sugar as a placebo. These results suggest that horses in light to moderate work receiving a commercial concentrate may not require additional low-dose electrolyte supplementation.