Influence of carbohydrate source on digesta kinetics and postprandial glucose responses of broiler chicks

• Effect of carbohydrates on digesta kinetics and plasma glucose response was studied.
• Different carbohydrate sources affected digesta kinetics and plasma glucose response.
• Cassava starch significantly influenced digesta kinetics parameters studied.
• Millet starch provoked higher postprandial plasma glucose responses in broiler chicks.
• No relationship was observed between digesta kinetics and plasma glucose responses.

This study was conducted to investigate the effect of different carbohydrates included in the diets of broiler chicks on digesta kinetics and postprandial plasma glucose responses. Starch extracted from different energy feedstuffs, maize, wheat, millet, sweet potato, and cassava, was used as the main energy source in each diet. Ninety 1-d-old broiler chicks were assigned to 5 diets containing 45±3% of each starch with 3 replicates and 6 broiler chicks per replicate. The digesta kinetics study involved administering 50 mg chromic oxide orally to each broiler chick before feeding. Excreta produced was collected hourly for the first 8 h and 10, 12, 24, 36, and 48 h, and their Cr2+ content determined. Cumulative Cr2+ excretion, times at 1 (T1) and 50% (T50) Cr2+ excretion, time at peak Cr2+ excretion, and mean retention time (MRT) were estimated. Two broiler chicks per replicate were used for the plasma glucose response study where glucose concentration was measured from blood collected from the wing vein of each broiler chick up to 480 min postprandial. Postprandial glucose responses, as well as hydrolysis indices were calculated. Digesta transit time variables, T1, T50, time at peak Cr2+ excretion, and MRT varied and were greatest for cassava starch diet at 0.2, 6.20, 8.00, and 19.45 h, respectively, and least for the sweet potato starch diet at 0.1, 4.2, 5.0, and 17.20 h, respectively. Plasma glucose response variables also varied considerably (P<0.05) between treatments and were attributed to starch granule size and dimensions. However, no relationship was observed between digesta kinetics and postprandial glucose responses of broiler chicks fed the experimental diets.