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Animal : an international journal of animal bioscience2017; 11(9); 1558-1566; doi: 10.1017/S1751731117000556

The effect of rider weight and additional weight in Icelandic horses in tölt: part I. Physiological responses.

Abstract: This study examined the effect of increasing BW ratio (BWR) between rider and horse, in the BWR range common for Icelandic horses (20% to 35%), on heart rate (HR), plasma lactate concentration (Lac), BWR at Lac 4 mmol/l (W4), breathing frequency (BF), rectal temperature (RT) and hematocrit (Hct) in Icelandic horses. In total, eight experienced school-horses were used in an incremental exercise test performed outdoors on an oval riding track and one rider rode all horses. The exercise test consisted of five phases (each 642 m) in tölt, a four-beat symmetrical gait, at a speed of 5.4±0.1 m/s (mean±SD), where BWR between rider (including saddle) and horse started at 20% (BWR20), was increased to 25% (BWR25), 30% (BWR30), and 35% (BWR35) and finally decreased to 20% (BWR20b). Between phases, the horses were stopped (~5.5 min) to add lead weights to specially adjusted saddle bags and a vest on the rider. Heart rate was measured during warm-up, the exercise test and after 5, 15 and 30 min of recovery and blood samples were taken and BF recorded at rest, and at end of each of these aforementioned occasions. Rectal temperature was measured at rest, at end of the exercise test and after a 30-min recovery period. Body size and body condition score (BCS) were registered and a clinical examination performed on the day before the test and for 2 days after. Heart rate and BF increased linearly (P0.05), but negative correlations (P<0.05) existed between body size measurements and Hct. While HR, Hct and BF recovered to values at rest within 30 min, Lac and RT did not. All horses had no clinical remarks on palpation and at walk 1 and 2 days after the test. In conclusion, increasing BWR from 20% to 35% resulted in increased HR, Lac, RT and BF responses in the test group of experienced adult Icelandic riding horses. The horses mainly worked aerobically until BWR reached 22.7%, but considerable individual differences (17.0% to 27.5%) existed that were not linked to horse size, but to back BCS.
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Publication Date: 2017-03-21 PubMed ID: 28320488PubMed Central: PMC5561439DOI: 10.1017/S1751731117000556Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This study aimed to understand how increasing the body weight ratio (BWR) between a rider and an Icelandic horse affects the animal’s physiological responses. The research concluded that as BWR increases, the horse’s heart rate, plasma lactate concentration, body temperature, and breathing frequency also increase, indicating a greater degree of physical stress.

Research Methodology

  • The study involved eight experienced school-horses undergoing an incremental exercise test performed on an outdoor oval riding track. A single rider rode all the horses to maintain control and consistency.
  • The exercise test had five phases where the body weight ratio (BWR) between the rider (including the saddle) and the horse initially started at 20% and was increased in increments up to 35%. After reaching 35%, it was decreased back to 20%.
  • After each phase, the horses were briefly stopped to add lead weights to the rider’s specially adjusted saddle bags and vest to increase the BWR.
  • During the warm-up, the exercise test, and the recovery periods, the researchers measured the horses’ heart rate, and took samples to ascertain their plasma lactate concentration and breathing frequency.
  • Rectal temperature was also measured before and after the exercise, and after a 30-minute recovery period.
  • The researchers also noted body size, body condition score and performed clinical examinations before and after the test.

Findings and Conclusion

  • As BWR increased, the heart rate, plasma lactate concentration (an indicator of stress and fatigue), body temperature, and breathing frequency of the horses also increased. This pointed towards increased physical strain on the horses with increased BWR.
  • While the heart rate, hematocrit (ratio of red blood cells to total volume of blood), and breathing frequency recovered to their normal levels within 30 minutes of the exercise, the plasma lactate concentration and rectal temperatures did not, pointing to prolonged physiological effects of increased BWR.
  • Interestingly, the study found individual differences among horses, meaning that the percent of BWR at which horses began to work aerobically (using oxygen to meet energy demands) varied between 17% and 27.5%. This variance was not linked to the horse’s size, but to its body condition score (an assessment of fat coverage on a horse’s body).
  • The study thus concluded that increasing the BWR from 20% to 35% indeed led to significant physiological changes in the robust Icelandic horses.

Cite This Article

APA
Stefánsdóttir GJ, Gunnarsson V, Roepstorff L, Ragnarsson S, Jansson A. (2017). The effect of rider weight and additional weight in Icelandic horses in tölt: part I. Physiological responses. Animal, 11(9), 1558-1566. https://doi.org/10.1017/S1751731117000556

Publication

Animal : an international journal of animal bioscience
ISSN: 1751-732X
NlmUniqueID: 101303270
Country: England
Language: English
Volume: 11
Issue: 9
Pages: 1558-1566

Researcher Affiliations

Stefánsdóttir, G J
  • 1Department of Equine Science,Hólar University College,IS-551 Sauðárkrókur,Iceland.
Gunnarsson, V
  • 1Department of Equine Science,Hólar University College,IS-551 Sauðárkrókur,Iceland.
Roepstorff, L
  • 3Department of Anatomy, Physiology and Biochemistry,Swedish University of Agricultural Sciences,750 07 Uppsala,Sweden.
Ragnarsson, S
  • 1Department of Equine Science,Hólar University College,IS-551 Sauðárkrókur,Iceland.
Jansson, A
  • 1Department of Equine Science,Hólar University College,IS-551 Sauðárkrókur,Iceland.

MeSH Terms

  • Animals
  • Body Weight / physiology
  • Exercise Test / veterinary
  • Female
  • Gait / physiology
  • Heart Rate / physiology
  • Hematocrit / veterinary
  • Horses / physiology
  • Iceland
  • Lactic Acid / blood
  • Male
  • Physical Conditioning, Animal / physiology
  • Respiration
  • Weight-Bearing / physiology

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Citations

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