Exercise- and metabolism-associated blood variables in Standardbreds fed either a low- or a high-fat diet.

This research article investigates the effects of feeding either a high- or low-fat diet on exercise and lipid metabolism-associated blood variables in Standardbred horses during moderate exercise.

Research Methodology

• The study was conducted as a cross-over experiment on 6 Standardbred horses. They were fed either a high-fat diet, which contained 11.8% fat in total dietary dry matter, or a low-fat diet, containing 1.5% fat. Each feeding period lasted for 4 weeks.
• At the end of each feeding period, a standardised submaximal stepwise exercise test on a treadmill was administered to the horses. Blood samples were taken before the exercise started, during the last 10 seconds of each exercise step, and after recovery (which comprised of 40 minutes walking).

Outcome of the Experiment

• The research found no difference in pre-exercise values for several blood variables, like plasma lactate, pH, ionised sodium, potassium, calcium, chloride, glucose, nonesterified fatty acids, and glycerol between the two diets.
• However, the concentration of triacylglycerols was found to be significantly lower when horses were fed a high-fat diet compared to a low-fat diet. Conversely, the concentrations of cholesterol, HDL cholesterol, and phospholipids were found to be significantly higher in the high-fat diet.
• A significant finding was that plasma lactate accumulation during exercise was less when the horses were given a high-fat diet. Lactate accumulation is associated with the onset of fatigue; hence this result indicates that high-fat diet may help delay fatigue during exercise.
• The study also found that horses on a low-fat diet had significantly different plasma lipid values compared to when they were on a high-fat diet. However, the changes in these values during and after moderate exercise were comparable for both diets.

Conclusion

• The results of the study suggest that fat metabolism in horses is significantly adapted on a high-fat diet. The authors suggest that feeding such a diet may enhance potential performance by delaying lactate accumulation and thereby delaying the onset of fatigue, a critical aspect in equine performance.