Standardized ileal digestible amino acids and digestible energy contents in high-protein distiller's dried grains with solubles fed to growing pigs1

Abstract

Chemical composition and, therefore, potential nutritive value of corn distiller's dried grains with solubles (DDGS) is constantly evolving as the ethanol industry innovates processing techniques. We determined standardized ileal digestibility (SID) of AA (Exp. 1) and DE (Exp. 2) contents in high-protein (HP; >40% on a DM basis) DDGS samples. Two HP DDGS (HP-A and HP-B) samples and 1 conventional DDGS (CON) sample were selected for this study. Three semipurified corn starch-based diets (minimum 18% CP, as-fed basis) were formulated with DDGS as the sole source of AA. A fourth, N-free diet was prepared to estimate basal ileal endogenous AA losses. The corn starch:sucrose:oil ratio was kept constant across diets to allow calculation of DE content in DDGS by the difference method. In Exp. 1, 8 ileal-cannulated barrows (23.9 kg initial BW) were used in a replicated 4 × 4 Latin square design ( = 8). Pigs were fed at 2.8 × maintenance energy requirement. In each period, pigs were adjusted to diets for 5 d followed by a 2 d of 8 h each grab continuous ileal digesta collection. In Exp. 2, 9 barrows (24.9 kg BW) were assigned to the 4 diets in a repeated 9 × 4 Youden square design to give 9 replicates per diet. In each period, pigs were adjusted to diets for 7 d followed by 5 d of fecal grab sample collection. The analyzed CP was 30.1, 42.3, and 43.1% (on a DM basis) in the CON, HP-A, and HP-B samples, respectively; the corresponding values for GE were 5,067, 5,425, and 5,407 kcal/kg DM, respectively. The concentrations of fat and NDF were comparable among the DDGS samples. Except for Arg and Val, the SID values for indispensable AA were not different ( > 0.05) among the 3 DDGS samples. However, HP samples had higher ( < 0.05) SID values for indispensable AA and CP compared with the CON sample. The SID of Lys content was 4.9, 6.1, and 7.4 g/kg DM for the CON, HP-A, and HP-B, respectively; the corresponding values for Met and Thr were 4.6, 6.8, and 7.4 g/kg DM, respectively, and 6.8, 9.5, and 10.7 g/kg DM, respectively. The DE content in HP samples was greater ( < 0.01) than in the CON (3,614, 4,494, and 4,555 kcal/kg DM for the CON, HP-A, and HP-B, respectively). In conclusion, HP DDGS had higher SID content of AA and DE compared with the CON.