Nutrient digestibility and energy utilisation of diets based on wheat, sorghum or maize by the newly hatched broiler chick.

1. Two experiments were conducted to measure changes in nutrient utilisation in the newly hatched broiler chicken. The first experiment determined the nitrogen-corrected apparent metabolisable energy (AME(N)) and total tract digestibility of starch and fat in diets based on wheat, sorghum and maize during the first two weeks post-hatch. The second experiment was conducted to confirm the results of Experiment 1 using wheat- and maize-based diets and was of 21 d duration. 2. In both experiments, changes to AME(N) with age were similar irrespective of the diet type, declining from d 3 to d 5-9 and then increasing after d 9. 3. In Experiment 1, the total tract digestibility of starch and fat exhibited a pattern similar to that of AME(N). 4. In Experiment 1, cereal effects were significant, with maize- and sorghum-based diets having higher AME(N) values than the wheat-based diet. Total tract starch digestibility determined for d 5, 7 and 14 showed no cereal differences. Total tract fat digestibility on d 7 was significantly lower for the wheat- and sorghum-based diets than for the maize-based diet, but no cereal differences were observed on d 5 or 14. 5. In Experiment 2, cereal effects were significant, with the maize-based diet having a higher AME(N) than the wheat-based diet. 6. These results showed that nutrient utilisation is compromised during the first week of life of the broiler chick.