O2 transport in the horse during rest and exercise.

The study involves investigating how oxygen transport in horses changes from a state of rest to a state of exercise. It’s found that horses have a remarkable ability to transfer oxygen during exercise, achieving a massive increase in consumption compared to humans.

Research Methodology

• The research was conducted on six adult horses aged between 2 to 5 years. The horses were studied both at rest and while doing steady exercise on a treadmill, reaching speeds of 12 meters/second, achieved during a submaximal gallop.
• The researchers measured the horses’ oxygen consumption using an open-flow system. An open-flow system allows for a continuous supply of gas, in this case, oxygen, from a source to the demand site or the body. This type of system enables more precise measurements of oxygen consumption.
• Arterial and mixed venous blood samples were taken from the horses for evaluation of oxygen content and hemoglobin concentration. Hemoglobin is the protein in red blood cells that carries oxygen from the lungs to the body’s tissues and returns carbon dioxide from the tissues back to the lungs.

Findings

• At rest, the horses’ oxygen consumption (VO2) was measured at 1.5 ± 0.2 L/min. But this rate increased significantly to 46.2 ± 4.8 L/min during exercise, exhibiting a substantial boost in oxygen uptake when the animal was physically active.
• The researchers also monitored the horses’ heart rates, which rose from a resting average of 36.9 bpm ± 2.5 bpm to 196.5 bpm ± 10.9 bpm during exercise. This increase backs up the reported growth in oxygen consumption during physical activity.
• The arterio-venous oxygen content difference (a-v O2), which is a measure of the difference in oxygen levels between the arterial and venous blood, also saw a significant leap from 4.2±0.8 ml O2/100 ml blood to 20.3±1.6 ml O2/100 ml blood. This change points towards an intensified usage of oxygen by the body’s tissues during exercise.

Conclusion

• The research concluded that the horse has a noteworthy ability to transport and use oxygen, marked by a 30.4-fold increase in oxygen consumption during a state of moderate exercise as compared to rest. In contrast, humans exhibit only a 10-fold increase at maximum oxygen uptake. This substantial difference underscores the horse’s superior O2 absorption and usage capabilities during physical activity.