title: High glycemic and insulinemic responses to meals affect plasma growth hormone secretory characteristics in Quarter Horse weanlings.
abstract: Growth hormone is a key component of the somatotropic axis and is critical for the interplay between nutrition, regulation of metabolic functions, and subsequent processes of growth. The objective of this study was to investigate potential relations between meal feeding concentrates differing in the glycemic responses they elicit and GH secretory patterns in young growing horses. Twelve Quarter Horse weanlings (5.4 ± 0.4 mo of age) were used in a crossover design, consisting of two 21-d periods and two treatments, a high-glycemic (HG) or low-glycemic (LG) concentrate meal, fed twice daily. Horses were individually housed and fed hay ad libitum. On the final day of each period, quarter-hourly blood samples were drawn for 24 h to measure plasma glucose, insulin, non-esterified fatty acids, and GH. Growth hormone secretory characteristics were estimated with deconvolution analysis. After a meal, HG-fed horses exhibited a longer inhibition until the first pulse of GH secretion (P = 0.012). During late night hours (1:00 AM to 6:45 AM), HG horses secreted a greater amount of pulsatile GH than LG horses (P = 0.002). These differences highlight the potential relations between glycemic and insulinemic responses to meals and GH secretion. Dietary energy source and metabolic perturbations associated with feeding HG meals to young, growing horses have the potential to alter GH secretory patterns compared with LG meals. This may potentially affect the developmental pattern of various tissues in the young growing horse.
authors: Department of Animal Science, The Pennsylvania State University, University Park, PA 16802, USA.
authors: S M
authors: SM
authors: Gray
authors: P A
authors: PA
authors: Bartell
authors: W B
authors: WB
authors: Staniar
mesh_terms: D000821:Animal Feed; D000818:Animals; D001786:Blood Glucose / Q000032:analysis*; D001823:Body Composition; D018592:Cross-Over Studies; D004032:Diet / Q000662:veterinary*; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D038321:Glycemic Index; D013006:Growth Hormone / Q000097:blood* / Q000378:metabolism; D006736:Horses / Q000097:blood*; D007328:Insulin / Q000097:blood*; D008297:Male; D019518:Postprandial Period / Q000502:physiology; D014886:Weaning
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D013006:Growth Hormone