Effects of Extrusion on Energy Contents and Amino Acid Digestibility of Corn DDGS and Full-Fat Rice Bran in Growing Pigs

SIMPLE SUMMARY: Our study showed that extrusion improves nutritive value, apparent total tract digestibility of nutrients and ileal digestibility of most amino acids in full-fat rice bran and corn distillers dried grain with solubles, which suggests that extrusion could be an effective strategy to improve nutritive values of feed by-products. ABSTRACT: The objectives of this study were to determine the effects of extrusion on available energy, apparent total tract digestibility (ATTD) of nutrients and energy, and amino acid (AA) digestibility of full-fat rice bran (FFRB) and corn distillers dried grain with solubles (DDGS) fed to growing pigs. Methods: In Exp. 1, a total of 30 growing pigs with initial body weight (BW) of 36.0 ± 1.8 kg were fed five different diets, including one corn basal diet and four experimental diets which were formulated by 29.06% FFRB or DDGS with or without extrusion processing. In Exp. 2, 30 ileal-cannulated pigs (initial BW: 20.3 ± 1.8 kg) were fed five different diets including 40% FFRB or DDGS with or without extrusion, and a N-free diet. Results: The results showed that there were no significant differences in DE and ME contents or ATTD of GE, DM, and OM between DDGS and FFRB (p > 0.05), but the ATTD of CP, NDF, and ADF showed significant differences between DDGS and FFRB (p < 0.05). In addition, the DE and ME values (p < 0.01) and ATTD of GE, DM, OM, and NDF improved when pigs were fed extruded diets (p < 0.05), and a trend to increase the ATTD of CP and ADF was observed when pigs were fed extruded diets (p = 0.06 and 0.07, respectively). The AID and SID levels of CP were not different when pigs were fed diets with or without extrusion. The AID of total indispensable AA increased when pigs were fed extrusion diets (p < 0.05). Conclusion: Feed processing of extrusion could improve nutritive values of FFRB and DDGS.