Elsevier

Journal of Equine Veterinary Science

Volume 49, February 2017, Pages 108-112
Journal of Equine Veterinary Science

Original Research
Effect of Marcha Exercise on Serum Electrolytes and Acid–Base Balance in Mangalarga Marchador Horses

https://doi.org/10.1016/j.jevs.2016.10.018Get rights and content

Highlights

  • The marcha is a comfortable lateral and diagonal gait.

  • Depending on its intensity and duration, the exercise has effects on acid–base balance.

  • After a marcha competition, only the stallions presented hypochloremic metabolic alkalosis.

  • In experiments with athletic horses, gender differences should be taken into consideration.

Abstract

The marcha competition is a functional evaluation, without similar in the world. In this competition, the animals perform marcha at average speed between 9 and 12 km/hr for 50 minutes, covering roughly 6 to 7 km with no rest. The aim of this study was to evaluate and compare the effect of batida gait competition on acid–base balance in Mangalarga Marchador horses during an official marcha competition. The study was conducted on 24 Mangalarga Marchador horses, 12 stallions, and 12 mares (aged 4–6 years and 399 ± 45 kg of body weight). Venous blood samples were collected before and after competition. Blood samples were analyzed for acid–base balance, as well as biochemical and electrolyte parameters. In stallions, a significant (P < .05) postexercise increase in pH, partial pressure of oxygen, bicarbonate concentration, base excess, and glucose was noted. Decrease (P < .05) in pCO2 (partial pressure of carbon dioxide), chloride and ionized calcium were observed after exercise only in stallions. No changes (P > .05) in hematocrit, hemoglobin, sodium, and potassium were observed after exercise in all animals. The changes in the acid–base balance and electrolyte profile of the Mangalarga Marchador stallions after marcha competition resulted in hypochloremic metabolic alkalosis. Marcha competition did not cause acid–base disturbance in mares. This study enables an evaluation and comparison of physical effort caused by the marcha exercise on acid–base balance in Mangalarga Marchador horses and provides further evidence of the existence of gender differences in sports horses.

Introduction

The Mangalarga Marchador horse is the most important and numerous Brazilian equine breed, and its natural gait is marcha rather than trot [1], [2]. There are approximately 350,000 registered Mangalarga Marchador horses in Brazil. Other Brazilians breeds have gaits with similar characteristics, such as Campolina, Mangalarga, and Piquira [1].

The marcha is a comfortable four-beat lateral and diagonal gait with moments of triple support and no suspension [3]. The ideal range of speed of the marcha gaits is 3.0 to 4.0 m/s because this speed allows maximum stability, with significant moments of triple support and a four-beat sequence and the absence of aerial phase [4]. The Mangalarga Marchador horses have at least two natural types of four-beat gaits. The picada gait is a broken pace with little vertical movement of the rider. The batida gait is a broken trot with significant movements of the legs in a diagonal pattern and with a vertical rider's movement [1].

Mangalarga Marchador horses have been submitted to different sporting disciplines, including endurance races, cavalcades, and marcha competitions [2]. The marcha competition is a functional evaluation of Mangalarga Marchador horses, without similar in the world [5]. The effort is predominantly aerobic and moderate-intensity submaximal, where horses must perform four-gaited exercise at 13 km/hr for approximately 50 minutes with no rest [2], [3], [5].

The effects of marcha exercise on a number of physiological, hematological, and biochemical parameters in the Mangalarga Marchador horse have been reported [1], [6], [7]. During the four-beat gait challenges, the red blood cells, hematocrit (HCT), hemoglobin (HGB), white blood cells, and total plasma protein rose and remained high after the 4-hour rest [6]. After a simulated marcha field test, significant increases were observed in heart rate, respiratory rate, HCT, total protein, and glucose (GLU) concentration [1]. It was demonstrated that picada horses expend more energy when compared with batida horses at the same speed [1]. Finally, marcha exercise induced significant hematologic and biochemical changes in serum of Mangalarga Marchador horses, independently of gender [7]. However, in this study, females presented more blood changes after marcha gait [7].

Currently, there is a lack of information about the effect of the marcha competition on acid–base balance in Mangalarga Marchador horses. Therefore, it has been hypothesized that horses in marcha exercise have significant changes in venous blood gas analysis. The aim of this study was to evaluate the effect of marcha exercise on acid–base balance and biochemical parameters of Mangalarga Marchador horses in an official competition and whether this differs in male and female horses.

Section snippets

Horses and Competition

All procedures applied in this study were approved by the Ethics Committee for Tests with Animals of Universidade Estadual do Norte Fluminense Darcy Ribeiro (number 2014/250). Evaluations were carried out during a marcha gait in a rodeo park in the city of Campos dos Goytacazes, Rio de Janeiro, Brazil (south latitude 20°48′21″, west longitude 40°38′52″ and altitude 13 m). The mean temperature during the competitions was 26°C, and relative humidity was 72%.

Twenty-four Mangalarga Marchador horses

Results

The values of horses’ blood gasometric parameters before the competition demonstrated the acid–base balance state (Table 1). Postexercise, the values of pH, pO2, HCO3, and BE showed a significant increase in stallions (P < .05), whereas the values of pCO2 decrease significantly (P < .05) in these same animals.

Mean values of blood hematological indices in horses are presented in Table 2. No significant differences (P > .05) were observed between before and after exercise levels of HCT and HGB

Discussion

The significant increase of pH in stallions after the marcha exercise was probably caused by increase pCO2 elimination due to hyperventilation. HCO3 and BE could be connected with the excessive Cl loss through perspiration during the marcha competition. Chloride is the most abundant anion in extracellular fluid, and Cl and HCO3 are the only important resorbable anions in renal tubular fluid. Loss of Cl ions from serum results in an increased secretion of HCO3 ions, in order to maintain

Conclusions

In conclusion, this study demonstrated that marcha competition results in acid–base and electrolytic imbalance only in Mangalarga Marchador stallions. Therefore, the gender differences in studies of sports horses should be taken into consideration.

Acknowledgments

The authors declare no competing interests. None of the authors has any financial or personal relationships with other people or organizations that could inappropriately influence or be perceived to influence the content of the paper.

P.A.D.F., L.P.M., and M.A.D.M. participated in the design of the study, supervised the experiments, revised and submitted the final manuscript. L.P.M., L.M.M., L.M.F.R., I.S.V., and R.M.S.P. participated in the study from the early phase to the end of data

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