Changes in certain metabolic parameters in horses associated with food deprivation and endurance exercise.

This research investigates how horses’ metabolic parameters change in scenarios of endurance exercise and food deprivation, looking particularly at various fatty acids, glucose, and insulin. The study found that certain non-esterified fatty acids increased significantly both during intense exercise and periods of no food, and that feeding caused a significant decline in these fatty acids and a rise in insulin levels.

Understanding the Metabolic Parameters

• The metabolic parameters monitored in the study include individual non-esterified fatty acids (NEFA), pyruvate, lactate, alpha ketoglutarate, acetoacetate, beta hydroxybutyrate, glucose, and insulin. These molecules play crucial roles in the body’s metabolism, energy production, and hormonal regulation.
• NEFA in particular became significantly elevated both during the 80 km endurance ride and during four days of food deprivation, indicating the body’s shift in energy utilization from carbohydrates to fats in times of intense physical activity or lack of food.
• The prominent NEFA in these circumstances were oleic, palmitic, linoleic, and linolenic acids.

Impacts of Feeding on Metabolic Parameters

• The total NEFA were found to decrease to around 20% of their levels after 12 hours of fasting, one hour after feeding. This suggests that consuming food outright sparks a metabolic reaction, shifting the body from its fat-burning state back to a carbohydrate-burning one.
• This decrease in NEFA was correlated with a fourfold increase in insulin, a hormone released by the pancreas that regulates glucose utilization, underscoring the body’s return to carbohydrate utilization after eating.

Effects of Food Deprivation and Endurance Exercise

• Small but significant increases were noted in lactate, acetoacetate, and beta hydroxybutyrate after the 80 km endurance ride. These metabolites are produced during anaerobic metabolism and fat oxidation, reinforcing the metabolic shift in the horse’s body during strenuous exercise.
• The researchers concluded that the ketone pathway, often important in other mammals during extended physical exertion or starvation, is relatively less significant in the horse, possibly because of the liver’s ability to maintain glycogenolysis, the breakdown of glycogen to glucose for energy use.