Uric Acid Determination in Poultry Excreta and its Application to Correcting Protein Digestibility Values: Spectrophotometry with Ultraviolet Detection vs HPLIC

Evaluation of uric acid contents of poultry excreta was examined for use in the estimation of apparent protein digestibility. Uric acid was determined either by high-performance liquid chromatography or by spectrophotometric method. A high-pressure liquid chromatographic assay was used with absorbance measured at 285 nm. The method used a reverse-phase system with a C18-bonded column (250*4.6 mm, i.d.). The mobile phase was distilled deionized water. Injection volume was 20 l with a flow rate of 1 ml/min. Correlation (r) between the two methods for uric acid content of excreta from birds fed diets with different methionine levels was 0.976. The uric acid values were then used to determine apparent protein digestibility. The apparent protein digestibility values, when corrected for uric acid nitrogen, were comparable with those calculated from amino acid analysis.