Standardised ileal digestibility of amino acids and apparent metabolisable energy contents of cereal ingredients fed to broiler chickens as affected by growth period and energy evaluation method.

Abstract

1. This study evaluated metabolisable energy (ME) and amino acid (AA) ileal digestibility in different cereals and processing for 9 d old broilers. It compared energy estimates derived using the total collection versus the indigestible marker methods and investigated growth period-related differences in energy release and ileal AA digestibility.2. Six experimental diets were formulated as mashed diets, including a nitrogen-free control and five semi-purified diets each using maize, extruded maize, wheat, fine wheat flour, or barley as the sole source of energy and AA. A total of 480 male Ross 308 broilers, aged 5 d old, were allocated to one of the six treatments each with eight pen replicates as a randomised complete block design.3. Interactions existed (p < 0.001) between collection method and cereal ingredient on ME. The total collection method gave higher results (p < 0.05) than the indigestible marker method, particularly for barley and wheat.4. Fine wheat flour had the greatest (p < 0.05) apparent and standardised AA ileal digestibility, followed by maize, extruded maize, wheat and barley. In the grower period, ME and ileal AA digestibility improved, and these responses were dependent on cereal and processing method.