Effect of load on preferred speed and cost of transport.

This research studies if horses change their preferred trotting speed when carrying a load. The study found that horses did reduce their preferred trotting speed when carrying a load, likely to maintain energy efficiency.

Introduction

• The study focuses on preferred speed in trotting horses, specifically examining if they adjust this speed when loaded with 19% of their body weight.
• It was hypothesized that if metabolic economy (defined as cost of transport, CT) and preferred speeds were intertwined, then changes in metabolic economy (symbolized by shifts in CT) should lead to changes in preferred speed.

Methodology

• The study was conducted on seven horses measured for their preferred speed in two conditions: unloaded and loaded.
• The load was equivalent to 19% of the horse’s body weight.
• The preferred speed on a level surface was measured for each horse in both conditions.
• In addition, in both states (loaded and unloaded), the rate of oxygen consumption was measured as this has been linked to the energy efficiency of the horse.

Results

• The results showed a decrease in preferred speed when the horses were loaded as compared to when they were unloaded.
• The average preferred speed on level ground was found to be 3.33 +/- 0.09 m/s when unloaded, which decreased to 3.13 +/- 0.11 m/s when loaded.
• The study also found a curvilinear relationship between the rate of oxygen consumption (measured in only three horses) and the speed, implying the presence of a minimum CT or a speed at which trotting is most economical in terms of energy usage.
• This economical speed was found to be very close to the preferred speed under both conditions, unloaded and loaded.

Conclusions

• The findings support the hypothesis that the metabolic economy and preferred speed of trotting horses are interlinked.
• When carrying a load, horses seem to reduce speed to maintain the metabolic economy, effectively conserving energy.

This research contributes to a broader understanding of how horses adapt their behavior to changes in their environment or situations, such as carrying a load. Further research could extend these findings to other contexts or to studying how physiological mechanisms control this adaptation.