Effects of body weight gain on insulin and lipid metabolism in equines.

The study describes how weight gain impacts insulin regulation and lipid metabolism in horses and Shetland ponies. Researchers observed changes in various metabolic measurements over time as the test subjects were provided twice their usual energy intake.

Study Methodology and Participants

• The research looked at 19 healthy test subjects – 10 Shetland ponies and 9 warmblood horses.
• Blood samples were taken from the animals under fasting conditions, and a combined glucose-insulin test (CGIT) was performed.
• This process was repeated after both one and two years, during which the animals had been receiving double the energy they usually would for maintenance.

Observations Regarding Insulin and Glucose

• There was an increase in basal plasma glucose concentrations in ponies when comparing the readings from the start of the study and two years on.
• Basal serum insulin concentrations also increased, both in ponies and in warmblood horses, over the same period.
• However, 16 out of the 19 test subjects did not display any signs of insulin dysregulation according to the CGIT.

Findings on Lipid Metabolism

• The study also recorded changes in non-esterified fatty acids (NEFA) and triacylglycerides (TGs). Both these factors give an insight into lipid metabolism, which provides energy for the body’s cells.
• Researchers found that basal serum NEFA concentrations increased in ponies over the two-year period.
• During the CGIT, NEFA levels in all test subjects initially dropped to a lowest point before recovering back to basal concentrations.
• However, the minimum NEFA value did not change over time either in ponies or in horses.
• There was a strong correlation between basal serum NEFA concentrations and the percentage drop to this minimum level in Shetland ponies.
• In contrast, basal serum TG (a form of storage fat in animals) levels remained constant, undisturbed by weight gain or breed.

Further Implications

• Two out of three test animals identified as being insulin-dysregulated also contracted laminitis, which is a severe and painful condition of the hooves. These animals also showed a delay in the recovery of their minimum NEFA levels.
• These results suggest that serum NEFA concentrations during the CGIT are useful indicators for identifying insulin dysregulation in equines.

Conclusion and Future Research

• The study concludes that there is a clear impact on insulin and lipid metabolism with gain in body weight for horses and ponies.
• Future research should look more closely at lipid metabolism during insulin dysregulation in order to better understand these processes and how they affect the health of equines.