A 90-day adaptation to a high glycaemic diet alters postprandial lipid metabolism in non-obese horses without affecting peripheral insulin sensitivity.

The research investigates the effects of high glycaemic feeds on lean horses over a 90-day feeding period and finds that such diet doesn’t induce insulin resistance but may potentially influence the horses’ lipid metabolism.

Objective and Methodology of the Research

• The primary aim of the research was to study the effects of high glycaemic feeds on the insulin sensitivity of lean horses. Previous studies primarily focused on horses ranging from lean to obese, or horses fed to increase body condition; thus, this study fills that gap.
• The study was carried out on 18 lean horses which were respectively fed a non-structural carbohydrate complementary feed comprising 10% (LO group), 20% (MED group), and 60% (HI group) for 90 days.
• The research measured the insulin sensitivity by observing insulinaemic responses to feeding and using a glucose tolerance test.

Findings

• Contrary to the belief that high glycaemic feeds lead to insulin resistance in horses, the research found that neither the MED nor the HI diets resulted in insulin resistance, despite increasing insulinaemic responses in comparison with the LO diet.
• However, the study made an interesting discovery that the post-feeding suppression of plasma non-esterified fatty acids was less pronounced in HI-fed horses on days 30 and 90 of the study. This observation potentially indicates a possible reduction in insulin-induced suppression of adipose tissue lipolysis.

Implications and Future Research

• Although high glycaemic feeds did not induce insulin resistance, the observed potential alteration in lipid metabolism could signify an early event in the development of insulin resistance. Since insulin-resistant animals often experience elevated plasma lipid concentrations, changes in lipid metabolism could be a precursor to insulin resistance.
• As a result, the research suggests that the long-term effects of high glycaemic feeds on glucose and lipid metabolism should be further investigated to understand the potential risk of lean horses developing insulin resistance.