Indirect calorimetry, real-time interstitial glucose monitoring and blood sampling to determine effects of low, medium and high glycemic index cat foods

Tuesday, July 22, 2014: 9:30 AM
3501B (Kansas City Convention Center)
Kimberley D. Berendt , University of Alberta, Edmonton, AB, Canada
A. Kate Shoveller , Procter & Gamble Pet Care, Mason, OH
Ruurd T. Zijlstra , University of Alberta, Edmonton, AB, Canada
Abstract Text:

The amount and source of dietary starch affects glucose and insulin responses, and contributes to dietary glycemic index (GI) in omnivorous monogastrics. However, limited information exists for GI in carnivorous monogastrics such as cats. Thus, the objective was to study a range in dietary GI in relation to indirect calorimetry and postprandial serum glucose and insulin and interstitial glucose. We used 19 domestic shorthair cats in an incomplete replicated 3 × 3 Latin squares for 19 observations per diet. Initial BW averaged 4.9 kg and ranged from 3.4 to 7.1 kg. Three premium cat diets varying in GI based on ingredient composition (chicken & rice, chicken & chicken by-product meal, and turkey & chicken for high, medium, and low GI respectively) and starch content (36.8, 30.7, and 23.6%, respectively) were fed. Diets contained 38 & 23%,  36 & 22% , and 42 & 16% CP and ether extract, respectively. The respiratory quotient (RQ) decreased (P<0.001) with decreasing GI (0.78, 0.77, and 0.76 for high, medium and low GI, respectively), indicating increased lipid oxidation. Daily resting energy expenditure (REE) did not differ among diets. Postprandial (22 h) fat oxidation was inversely related to GI (0.64, 0.68, and 0.69 g/h for high, medium and low GI, respectively; P<0.05). Postprandial carbohydrate oxidation decreased with reducing GI (0.61, 0.52, and 0.46 g/h for high, medium and low GI, respectively; P<0.001). Postprandial (20 h) interstitial glucose decreased with reducing GI (73.4, 64.4, and 59.7 mg/dL d-1 for high, medium and low GI, respectively; P<0.05). Postprandial (10 h) serum glucose did not differ among diets and did not peak postprandially followed by return to baseline as expected based on data from responses of omnivorous monogastrics. Interstitial glucose may be more sensitive than a limited number of sequential blood samples to study starch metabolism in cats. Postprandial serum insulin was greatest (P<0.05) for the high GI diet and lowest for the medium GI diet. In conclusion, responses of cats to changes in dietary starch content are unique, i.e., more prolonged and less pronounced than in humans or dogs.

Keywords: glycemic index, calorimetry, cat