Palatability and Efficacy of Electrolyte Chews in Horses

Author

Grace Handlos, Southern Illinois University CarbondaleFollow

Date of Award

5-1-2023

Degree Name

Master of Science

Department

Animal Science

First Advisor

Perry, Erin

Abstract

The use of electrolytes in horses has become common in the equine community. Proper management of the equine athlete encourages the supplementation of electrolytes, especially during exercise. Electrolyte imbalance can cause physiological issues including fatigue, irregular heartbeat, cramping, and more. Electrolyte supplementation is utilized to replace losses via the sweat, urine, and defecation. Commercially available oral electrolyte forms include paste, powder, and pellets. Work describing chewable electrolyte use in horses has not been published. The objective of this work is two-fold: to determine preference across four electrolyte chew flavors and to ascertain efficacy of a novel electrolyte product. Protocol approval (#21-029) by Southern Illinois University Institutional Animal Care and Use Committee was obtained prior to initiation of this work. The study was completed in two phases. The first phase examined the palatability of the novel electrolyte chew while the second phase tested the serological effect of the product in exercising horses. In the first phase, stock-type horses (n = 10) were utilized for individual preference testing in palatability stocks over six days. During the palatability session, each horse was permitted 30 seconds to olfactorily investigate the product prior to release for consumption. Immediately following the olfactory period, each horse was allowed up to 5 minutes to voluntarily consume the electrolyte chews. Horses were presented with four treatments (A, B, C, D) on an alternating basis, with two treatments offered side-by-side per day. Treatment formulations consisted of the same base electrolyte content with varying flavors of peppermint, salt, and orchard grass (Table 2). Treatment locations were switched daily to prevent bias associated with location. Variables of interest included number of chews consumed (TI), first action (FA), first choice (FC), time spent consuming (TC) and water consumption (WC) were recorded. Bodyweight (BW) and body condition scores (BCS) were recorded twice over the study duration. Data were analyzed via numerical and categorical methods using PROC GENMOD, PROC FREQ & PROC GLM of SAS (v. 9.5). Significance was set at P < 0.05. There was no significant overall preference for any of the treatment formulations examined. However, there was a significant difference in chew consumption between days 1 and 2 (P = 0.0204). There was also a highly significant treatment effect between days 5 and 6 (P < 0.0001). The relationship between individual horse and consumption was variable and highly significant (P < 0.0001). The mean acceptance rate of the product was 63.6%. These results indicate palatability may differ significantly across horses for the flavors examined. In the second study phase, privately-owned local foxhunting horses (n = 15) were utilized in an exercise study. Due to poor consumption, nine horses were selected for use in the experiment to test treatments. There were three treatment groups: control (CON) offered no supplementation, light (LIG) consumed 6-9 chews, and moderate (MOD) voluntarily consumed 15-20 chews. Baseline jugular venipuncture and vitals assessments were completed on all horses prior to supplementation. Supplementation was offered in two parts: 30 minutes pre-ride and immediately following a 2-hour foxhunt ride in the afternoon. Afternoon temperature was 52°F with mostly sunshine and approximately 42% humidity. Upon return, horses were immediately offered electrolyte supplementation. Venipuncture and vitals assessments were repeated 30 minutes post-ride. Variables recorded were serum values (Na, K, Cl, Ca, HCO−3, Mg), chew consumption (TI), age, respiratory rate (RR), skin turgor (SKN), rectal temperature (BT), distance travelled (DIS) and average speed (SPD). Categorical variables were body condition score (BCS), sex, breed (BRD), and sweat rating (SWR). Data was analyzed via PROC GLM, PROC FREQ and PROC REG dependent on test with SAS (v. 9.5). Significance for all tests was set at P < 0.05. Serological values were unaffected by electrolyte consumption (P > 0.05). Body temperature was significantly higher for all horses following exercise, regardless of treatment group (P = 0.0005). Skin turgor showed significantly more time before return to original state during post-ride evaluation (P = 0.0013). Directional serum changes between Cl and K were significantly correlated (P = 0.0227) as well as Mg and Cl (P = 0.0316). Correlations of relational change between Ca and HCO−3 in addition to Ca and Na were approaching significance (P = 0.0707; P = 0.0800). Mares demonstrated a greater ability to maintain lower post-ride serum calcium levels than geldings (P = 0.013). The effect of breed on serological calcium change may also be considered (P = 0.0312). These results suggest that several major contributive factors require further investigation for the successful implementation of oral electrolyte chews into equine exercise regimens.