Abstract
The glycemic index (GI) impacts blood glucose levels, insulin sensitivity, and weight management in humans. This study investigated the GI, postprandial glycemic and insulinemic response, and satiety hormones in sled dogs consuming four commercial extruded dog foods containing different carbohydrate sources. The four test diets were classified based on carbohydrate sources: traditional grains (corn, wheat), whole grains (oats, rye), grain-free (peas, lentils) or vegan (no animal ingredients). Each diet was tested once and the control (50% w/vol glucose solution) was tested twice in 11 healthy adult Siberian Huskies in a randomized cross-over design. Each meal and control provided 25g of available carbohydrate. Pre- and postprandial (15, 30, 45, 60, 90, 120, 150, 180, 210, 240, 270, 300, 360, 420 & 480 minutes) blood samples were collected to measure whole blood glucose concentrations using a handheld blood glucose monitor. Serum insulin, ghrelin, gastric inhibitory polypeptide (GIP), glucagon-like peptide 1 (GLP-1), leptin, total peptide tyrosine-tyrosine (PYY), and pancreatic polypeptide (PP) concentrations were analysed using a magnetic bead multiplex assay. This study was approved by the University of Guelph Animal Care Committee (AUP#3650). No differences were detected in GI when compared using an ANOVA with a Turkey-Kramer post-hoc test (p>0.05). The calculated GI for traditional grains was 76.9 ± 18.3 (mean±SEM) while the grain-free diet presented the lowest GI of 50.5 ± 13.1. The whole grain diet and vegan diet had GI values of 60.8 ± 7.4 and 71.4 ± 17.3, respectively. Additionally, there was no effect of diet on postprandial insulinemic response, or any satiety hormones (p>0.05). The lack of observed differences could be related to the gelatinization of starch during extrusion processing. These results suggest that different carbohydrate sources in extruded diets may not have a significant effect on GI or satiety in dogs.
Keywords: Glycemic Index, Carbohydrates, Dogs