PSXIII-9 Effects of particle size and multi-enzyme supplementation on ileal digestibility of amino acids in roasted full-fat soybean and dry extruded soybean meal fed to growing pigs.

Abstract This study aimed to determine the effects of particle size and multi-enzyme supplementation on the apparent (AID) and standardized ileal digestibility (SID) of amino acids (AA) in roasted full-fat soybean (RFFS) and dry extruded soybean meal (DESBM) fed to growing pigs. A total of 18 ileal-cannulated barrows (40.1 ± 2.7 kg) were assigned to one of six dietary treatments in a triplicate 6 × 2 incomplete Latin square design, with six diets and two periods, providing six observations per treatment. Dietary treatments were arranged as follows: 1) four RFFS diets in a 2 × 2 factorial design, with two particle sizes, with or without multi-enzyme supplementation, and 2) two DESBM diets, with or without multi-enzyme supplementation. Each ingredient was included as the sole source of protein in diets. All diets contained 0.3% titanium dioxide as an indigestible marker. Each experimental period lasted 7 days, including the first 5 days for adaptation and the last 2 days for ileal digesta collection. Before feeding the experimental diets, all pigs were fed a low-protein diet for 7 days to quantify endogenous losses of nitrogen and AA to determine the SID of N and AA. Pigs were fed the diets at 2.8 times their maintenance energy requirement based on their body weight at the beginning of each period. All data were analyzed using single degree of freedom contrasts in the MIXED procedure of SAS to test the effects of ingredient (RFFS vs. DESBM), particle size, multi-enzyme supplementation, and the interaction between particle size and multi-enzyme supplementation within the four RFFS diets. The statistical model included diet as a fixed effect and replication, animal within replication, and period within replication as random effects. The AID and SID of crude protein and AA were greater (P < 0.05) in DESBM than in RFFS fed to pigs. There were no significant effects of particle size, multi-enzyme supplementation, or the interaction between particle size and multi-enzyme supplementation. In conclusion, the digestibility of AA was greater in DESBM than in RFFS fed to growing pigs, but particle size, multi-enzyme supplementation, and their interaction had no impact on AA digestibility in growing pigs.