Pullulans and γ-cyclodextrin affect apparent digestibility and metabolism in healthy adult ileal cannulated dogs

Pullulan and γ-cyclodextrin are incompletely digestible, glucose-based, nonstructural carbohydrates synthesized by microorganisms. To determine their effect when incorporated into a complete liquid diet on ileal and total tract nutrient digestibility, ileal cannulated dogs (n = 8) were used in a repeated 4 × 4 Latin-square design. Twice daily, diets were offered containing 30% (DMB) maltodextrin, high-molecular-weight (MW) pullulan (MW 100,000), low-MW pullulan (MW 6300), or γ-cyclodextrin. Fecal and ileal samples were collected for the last 4 d of each 10-d period. Dogs consuming high-MW pullulan had lower (P < 0.05) dry matter, organic matter, crude protein, fat, carbohydrate ileal and total tract digestibilities, and fecal DM, and higher (P < 0.05) fecal output and fecal scores (indicating looser stools). To evaluate glycemic and insulinemic responses to pullulans, food-deprived dogs consumed 25 g maltodextrin, high-MW pullulan, or low-MW pullulan in a repeated 3 × 3 Latin-square design. Glucose and insulin responses were determined for 180 min. Consumption of 25 g α-, β-, and γ-cyclodextrin resulted in regurgitation within 60 min. High-MW pullulan reduced (P < 0.05) blood glucose concentration at 15, 30, 45, and 60 min. Compared with maltodextrin, low-MW pullulan and γ-cyclodextrin did not alter nutrient digestibilities or fecal characteristics to any extent, and low MW pullulan did not affect glycemic response. Although high MW pullulan decreased glycemic response, consumption of large amounts negatively affected nutrient digestibility and fecal characteristics.