Two experiments were conducted to determine the concentration of digestible energy (DE) and metabolizable energy (ME) and the standardized ileal digestibility (SID) of amino acid (AA) in chicken meal, poultry byproduct meal, hydrolyzed porcine intestines, a spent hen–soybean meal (SBM) mixture, and conventional SBM fed to weanling pigs. Forty-eight barrows were placed in metabolism cages and allotted to six diets with eight replicate pigs per diet in a randomized complete block design. Corn-based diets were formulated containing 11 to 16% chicken meal, poultry byproduct meal, hydrolyzed porcine intestines, spent hen–SBM mixture, or SBM. All test ingredients were included in their respective diets at levels expected to equalize crude protein among diets. Feces and urine were collected for five days. The ME was estimated to be 3,957, 3,816, 4,586, 4,298, 4,255, and 4,091 kcal/kg dry matter for corn, chicken meal, poultry byproduct meal, hydrolyzed porcine intestines, the spent hen–SBM mixture, and SBM, respectively.
In the second experiment, 12 barrows weighing about 12.2 kg were equipped with a T-cannula in the ileum and allotted to a replicated 6 × 6 Latin square design. Diets were formulated by mixing cornstarch, sucrose, and SBM with chicken meal, poultry byproduct meal, hydrolyzed porcine intestines, or the spent hen–SBM mixture. Results indicated that the SID of crude protein and all AA, except Tryptophan and Proline, was greater (P < 0.01) in SBM than in all other ingredients. The SID of crude protein and all indispensable AA in the spent hen–SBM mixture was also greater (P < 0.01) than in chicken meal and hydrolyzed porcine intestines, and most of the indispensable AA in poultry byproduct meal. The ME in hydrolyzed porcine intestines and the spent hen–SBM mixture were greater than in chicken meal, but not different from the ME of SBM. The researchers concluded that poultry by product meal provides more ME than SBM, chicken meal, and the spent hen–SBM mixture, and the SID of most indispensable AA is greater in the spent hen–SBM mixture than in chicken meal, poultry byproduct meal, and hydrolyzed porcine intestines, but less than in SBM.