Additivity of Ileal Amino Acid Digestibility in Diets Containing Corn, Soybean Meal, and Corn Distillers Dried Grains with Solubles for Male Broilers

SIMPLE SUMMARY: There is limited information on the additivity on ileal digestibility of amino acids (AAs) in poultry diets containing corn distillers dried grains with solubles. The aim of this study was to test additivity of two types of ileal digestibility of AAs in mixed diets containing corn, soybean meal, and corn distillers dried grains with solubles in male Ross 308 broiler chickens. The apparent ileal digestibility of some amino acids in feed ingredients used in the study was not additive in mixed diets, whereas the standardized ileal digestibility of most amino acids was additive. Based on the results, standardized ileal digestibility values are more additive in poultry diets containing various feed ingredients compared with apparent ileal digestibility values. ABSTRACT: The aim was to test additivity of apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of amino acids (AAs) in mixed diets for Ross 308 broiler chickens. Two hundred and eighty-eight, 20-d-old male broiler chickens were assigned to one of six diets, with six birds per cage using a randomized complete block design. The diets consisted of a nitrogen-free diet, three diets containing corn, soybean meal (SBM), and corn distillers dried grains with solubles (CDDGS) as the sole source of nitrogen, respectively, and two mixed diets containing corn, SBM or CDDGS. Chromic oxide was added to the diets as an indigestible index. On day 24, birds were euthanized for ileal digesta collection. Relative proportion of the basal endogenous loss of AAs to total ileal outflow of AAs in corn was greater (p < 0.05) than that of SBM and CDDGS. For the corn-SBM and corn-SBM-CDDGS mixed diets, the AID of AAs differed (p < 0.05) from the predicted values. No difference was observed between the measured and predicted SID of AA. In conclusion, the SID of AAs is more additive in mixed diets containing corn, SBM, or CDDGS compared to AID values.