High-glycemic meal responses affect fundamental components of metabolic regulation in growing Quarter Horse weanlings

Open Access
Gray, Sarah Marie
Graduate Program:
Animal Science
Master of Science
Document Type:
Master Thesis
Date of Defense:
June 28, 2011
Committee Members:
  • William Staniar, Thesis Advisor
  • horse
  • growth hormone
  • deconvolution analysis
  • meal feeding
  • nutrition
The primary objective of this study was to investigate relationships between fundamental components of the somatotropic axis and concentrate meal responses in young, growing horses. Twelve Quarter Horse weanlings were utilized in a crossover design consisting of two 21-day periods, where treatments consisted of a twice-daily feeding of a high-glycemic (HG) or low-glycemic (LG) concentrate meal. On the final day of each period, blood samples were drawn every 15 minutes for a 24-hour period and analyzed for plasma glucose, insulin, non-esterified fatty acids and growth hormone concentrations. Growth hormone secretory patterns were estimated utilizing deconvolution analysis by AutoDecon software. Glucose and insulin peak concentrations and AUC were greater in HG than LG (P<0.05) in response to AM and PM meals. Growth hormone secretion following meals was inhibited for a longer time in HG horses as compared to LG horses, with a greater amount of GH secreted following this inhibition in HG. Nocturnal growth hormone secretion was greater in HG horses than LG. Elevated insulin responses to the two daily meals may potentially alter growth hormone secretion from the pituitary. This study provides insight into the mechanisms by which growth hormone may be altered by feeding strategies in the growing horse. Ultimately, this may impact processes of growth and metabolic regulation.