Utilization of various carbohydrate sources as affected by age in the chick

In 3 experiments, New Hampshire x Columbian male chicks were fed carbohydrate-soybean meal (SBM) or casein diets from 0 to 21 d of age, and ME_n was determined at 0 to 2, 3 to 4, 7, 14, and 21 d of age. Carbohydrate sources evaluated in experiment 1 were dextrose (D-glucose), conventional cornstarch, dextrinized cornstarch, corn-syrup solids, pregelatinized unmodified cornstarch, pregelatinized tapioca starch, tapioca dextrin, high-amylose starch, and polycose (mixed glucose polymers). Carbohydrate sources evaluated in experiments 2 and 3 were conventional corn, waxy corn, high-oil corn, corn flour, rice flour, dextrose, and sucrose. In experiment 1, chicks fed the dextrose diet had the highest weight gains, and the chicks fed high-amylose starch and pregelatinized unmodified cornstarch diets had the lowest weight gains. The ME_n values varied among carbohydrate sources with ME_n being highest for the dextrose diet and lowest for the high amylose starch diet. In experiment 2, chicks fed waxy corn, high-oil corn, or dextrose-SBM diets had (P < 0.05) higher growth rates than chicks fed conventional corn, corn flour, or rice flour. The ME_n values increased with age for all diets except the dextrose-SBM, which was consistently high at all ages. In experiment 3, the dextrose diets (SBM or casein) yielded higher growth performance and ME_n values than the sucrose-diets, and the differences were greater at younger ages. The ME_n values were also much higher for the casein than the SBM diets, and ME_n of the SBM diets increased with increasing age. The results of this study indicate that ME_n varies among carbohydrate sources and increases with age for most carbohydrate-SBM diets.