Metabolic adaptation to fat-supplemented diet by the thoroughbred horse.

This research investigates how a fat-supplemented diet impacts the metabolic adaptation of aerobically trained thoroughbred horses over a course of 10 weeks. The findings show a significant decrease in post-eating blood fat levels, an increase in fat-digesting enzymes associated with a higher cholesterol and an improved management of fat load resulting from its supplementation.

Objective and Methods of the Study

• The objective of the study was to observe the effects of a fat-supplemented diet on the metabolic functions in aerobically trained thoroughbred horses. This involved studying changes in horse characteristics such as plasma triacylglycerol concentration, lipase activity, cholesterol concentration, and muscle citrate synthase activity.
• The method used was a 10-week fat supplementation program, with data collected and analysed through various means, including administration of pentosan polysulfate.

Findings and Observations

• The research discovered a substantial decrease in plasma triacylglycerol concentration—this means that the amount of fat in the blood after a meal dropped significantly. This condition, called postprandial plasma triacylglycerol concentration, is associated with an increased risk of cardiovascular diseases.
• This decrease in plasma triacylglycerol was linked to a mean 50% increase in plasma total lipase activity, a consequence of pentosan polysulfate administration. Lipase is an enzyme that breaks down fats, so this increase implies an improved ability to digest fats.
• There was also an observed increase in postprandial plasma cholesterol concentration.
• The activity of muscle citrate synthase also significantly increased. This enzyme plays a critical role in the process of converting food into usable energy for the body.
• The study however found no significant change in the concentration of resting muscle glycogen or triacylglycerol as a result of the fat supplementation.

Conclusions and Suggestions

• The results suggest that fat supplementation led to improved management of the fat load and increased the horses’ triacylglycerol-clearing capacity (the ability to remove fats from their blood).
• The increase in lipase might be indicative of an increased muscle lipoprotein lipase activity, which would increase the capability of the muscle for free fatty acid uptake from circulating triacylglycerol-rich plasma lipoproteins.
• It was also suggested that fat supplementation might boost muscle’s oxidative capacity, as suggested by the considerable increase in muscle citrate synthase and the trend towards an increase in beta-hydroxyacyl CoA dehydrogenase following the supplementation period.