Effect of weight loss on lipid metabolism in the mature horse (814.4)

Abstract

Obesity currently affects over half of the nation’s horses, and causes concern as it poses increased disease risks and impairs various metabolic functions. Weight loss is considered a viable option to correct these maladies. Our objective was to determine if weight loss affected markers of lipid metabolism. Eight, mixed sex horses (5‐19 yr) were kept at an obese body condition score (BCS, 7‐8) for two weeks, then entered a six week period of 30% caloric restriction and light exercise to reach a moderate BCS (5). Blood samples collected every other week were analyzed for non‐esterified fatty acid (NEFA) and triglyceride concentration. Neck fat biopsies were also collected for ex vivo lipolysis analysis and media were analyzed for NEFA and free glycerol release. Plasma triglyceride and serum NEFA did not differ due to change in BCS or percent weight loss. Lipolysis, as indicated by release of NEFA, was decreased by change in BCS (p=0.01) and tended to be decreased by percent weight loss (p=0.07). Glycerol release was correlated (r=0.47, p=0.001) with NEFA release, but not significantly altered by change in BCS or percent weight loss. As an indicator of fatty acid oxidation, acyl‐CoA dehydrogenase mRNA expression was measured in skeletal muscle, but was not significantly affected. Therefore, as these horses transitioned to a leaner phenotype they exhibited only minor changes in lipid metabolism, indicating that while overweight they were not unhealthy.