Dietary Leucine Supplementation Does Not Influence Glycemic and Insulinemic Response in Yearling Quarter Horses

Open Access
Lambert, Nicole Michelle
Area of Honors:
Animal Sciences
Bachelor of Science
Document Type:
Thesis Supervisors:
  • William Staniar, Thesis Supervisor
  • Troy Ott, Honors Advisor
  • horse
  • glycemic response
  • insulinemic response
  • leucine supplementation
Supplementation with leucine results in an increase in muscle protein synthesis, glycogen synthesis and recovery, and an alteration in glycemic and insulinemic responses to glucose (Anthony et al., 1999; Anthony et al., 2001; Kalogeropoulou et al., 2008). In the horse, supplementation with leucine leads to increases in both the glycemic and insulinemic response to glucose administration (Urschel et al., 2010). This study’s goal was to assess the acute effects of dietary leucine supplementation on glycemic and insulinemic response to a meal. The initial hypothesis was that leucine supplementation would result in a dose-dependent increase in the insulinemic response to a meal. Using a replicated balanced latin square design, eight Quarter Horse yearlings each received four different treatments over the course of four weeks. These treatments consisted of a concentrate sweet feed mixed with either 0.0, 0.05, 0.1, or 0.2 g/kgBW leucine. Blood samples were collected via indwelling jugular catheters at -15, 0, 15, 30, 45, 60, 75, 90, 120, 150, 180, 240, 300, 360, and 420 minutes, with treatments being given directly after the 0 minute sample. Plasma was analyzed for glucose and insulin concentrations. There were no differences between the area under the curve (AUC) for insulin (p > 0.05). However, there was a difference (p = 0.0231) in glucose AUC between the 0.1 and 0.2 g/kgBW treatments. In conclusion, supplementation with leucine did not result in an increased insulinemic response. An increase in glucose area response was observed between the 0.1 and 0.2 g/kgBW leucine treatments. However, due to large variation in the glucose and insulin AUC responses to the supplemented meal, it was concluded that oral leucine supplementation does not have an effect on glucose or insulin responses in yearling Quarter Horses.