Effects of diet-induced weight gain and turnout to pasture on insulin sensitivity in moderately insulin resistant horses.

This research investigates the impact of weight gain through a fattening diet, and subsequent pasture turnout, on insulin sensitivity in moderately insulin resistant horses.

Methods

• The research was undertaken on 9 adult Standardbred mares which were between 11 to 20 years old.
• The mares underwent a period of weight gain for 22 weeks where they were fed a forage diet supplemented with increasing amounts of fat, eventually being fed at 2.5 times their daily maintenance requirements.
• Following this, the horses were then turned out to pasture.
• Insulin sensitivity was measured using the euglycemic hyperinsulinemic clamp method before and after the weight gain phase, and after four weeks on the pasture. Other measurements taken during the study included body weight, body condition score, cresty neck score, as well as plasma insulin, plasma glucose, serum triglyceride, and serum nonesterified fatty acid concentrations.

Results

• The body weight of mares typically increased by 10% during the weight gain period, and the body condition score also increased significantly.
• In contrast, there were no significant changes in insulin sensitivity or the metabolic clearance rate of insulin during the weight gain phase.
• After four weeks of being out to pasture, there were significant improvements in both insulin sensitivity and metabolic clearance rate of insulin (by 54% and 32% respectively), but no changes in body weight or condition.

Conclusion

• The findings suggest that dietary composition played a more crucial role in changes to insulin sensitivity in the horses, compared to short-term weight gain.
• This provides important insights into managing insulin resistance in horses and other similar animals.