Effect of feeding state on the response of horses to repeated bouts of intense exercise.

This research article investigates how the feeding status of horses (whether they’ve been fasted or recently fed) affects their metabolic responses to a regimen of intense exercise. The study found that the feeding status did not significantly influence the horses’ heart rates or lactate responses during intense workouts.

Study Design and Methodology

• The experiment involved four mature Standardbred horses in a 2-period cross-over design. This design allowed each horse to serve as both the experimental and control subject, undergoing both fed and fasted conditions.
• In the fed condition, horses were fasted for 12 hours and then given 2 kg of whole corn 2.5 to 3 hours before exercise. In the fasted condition, horses were not fed 15 to 16 hours prior to exercise.
• The exercise regiment consisted of two sessions of intense bouts separated by a 90-minute recovery period. Each exercise session included a warm-up phase and a high intensity phase. During the high intensity phase, the horses ran 1600 m at 11 m/s on a 2% graded treadmill.

Biomarkers and Measurements

• The researchers took blood samples during the exercise test to assess the levels of glucose, non-esterified fatty acids (NEFA), insulin, and lactate.
• The study found that fasted horses had lower insulin concentrations and higher NEFA concentrations at the start of exercise. This indicates that fasting may activate fat metabolism in horses in response to energy demands from intense exercise.
• The NEFA levels remained consistently higher in fasted horses until the high intensity phase of the second exercise bout.
• The heart rates and lactate responses to exercise in both groups were not affected by the feeding state. This suggests that the horses’ physical performance and lactate production – a sign of anaerobic metabolism during intense exercise – were not dependent on whether they had fasted or recently eaten.

Conclusions

• One interesting trend observed but not statistically significant was that plasma glucose levels tended to drop in fed horses during the first exercise bout. While not conclusive, this shows that recently fed horses could be using glucose as an energy source during exercise, which is worth further exploration.
• Overall, the study concluded that feeding state doesn’t have either a positive or negative effect on horses performing repeated bouts of intense exercise. This is important because it suggests that exercise performance in horses, at least in terms of heart rate and lactate responses, may not necessarily need to be adjusted according to their feeding times.