Physiological response to a breed evaluation field test in Icelandic horses.

The research article delves into the physical reactions—heart rate, breathing rate, haematocrit, body temperature, and some blood plasma changes—of Icelandic horses of different ages and sexes during a breed evaluation test ride. Over 200 horses, both stallions and mares of varying ages, were studied in Iceland and several measurements were taken pre and post riding. Findings showed stallions had a better aerobic fitness while age appeared to have minimal impact on the physical responses.

Methods of the study

• This study was conducted on 266 Icelandic horses, comprising 180 mares and 86 stallions, split into four age groups: 4 years, 5 years, 6 years, and 7 years and above.
• The physiological parameters recorded were heart rate and its peak, breathing rate, haematocrit (the amount of red blood cells in blood), rectal temperature, and certain plasma variables. These were noted both prior to the warm-up and after the riding assessment as part of the breed evaluation field test (BEFT).
• In addition, the horse’s velocity, total distance covered, and the distance covered in the BEFT were tracked during the warm-up, the riding assessment, and a 5-minute recovery period.

Findings of the study

• The study found that on average, the horses covered a distance of 2.9 km during the BEFT, with a duration of about 9 minutes and an average speed of 17.8 km per hour.
• The average heart rate was found to be 184 beats per minute (b.p.m.), with a peak of 224 b.p.m., and for 36% of the BEFT, heart rate was above 200 b.p.m.
• After the exercise, there was an increase in the plasma lactate concentration, total plasma protein, plasma creatine kinase and aspartate amino transferase concentration, breathing rate, rectal temperature, and haematocrit (Htc).
• The study showed stallions covered a greater distance at a higher speed during the BEFT. Stallions also showed a higher hematocrit value but lower heart rate and post-exercise lactate values, suggesting better aerobic fitness than mares.
• Age seemed to have a limited effect on the physiological response, although 4-year-old horses displayed higher post-exercise breathing rates, even though they were ridden for a shorter distance, duration, and peak velocity.

Implications of the study

• The study shows that the breed evaluation field test is a high-intensity exercise for horses, given the changes observed in physiological parameters like heart rate, breathing rate, etc.
• The findings also provide insights into the fitness level of horses based on their sex, with stallions demonstrating higher aerobic fitness.
• Even though the impact of age on physiological responses was limited, the results suggest that age can influence some variables like post-exercise breathing rates and haematocrit levels.
• These findings can help in designing tailored training programmes and fitness tests for Icelandic horses to improve their performance and welfare.