A comparison of amino acid digestibility bioassays for broilers

Apparent amino acid digestibilities determined in the lower ileum of broilers given free access to a diet containing normal or heat‐damaged soya protein were similar to “true” digestibilities determined with excreta using the Sibbald rapid bioassay.2. Higher ileal digestibilities were obtained with the Farrell rapid bioassay than with birds given free access to food. This pattern was reversed when measurements were made on excreta.3. Maximum absorption of amino acids had occurred by the time the di‐gesta had reached the upper ileum in birds fed on normal but not heat‐damaged soyabean protein.4. Heat damage to the soyabean protein was detected with all the bioassay procedures.