Digestibility of amino acids and concentrations of metabolizable energy and net energy are greater in high-shear dry soybean expellers than in soybean meal when fed to growing pigs

Abstract

Soybean expellers may be produced by dry extrusion and mechanical oil pressing of soybeans, but there is limited information about the nutritional value of expellers produced via this procedure. Therefore, 2 experiments were conducted to test the hypothesis that standardized ileal digestibility (SID) of CP and amino acids (AA), apparent total tract digestibility (ATTD) of energy and total dietary fiber (TDF), and concentrations of DE, ME, and NE are greater in soybean expellers than in soybean meal (SBM) when fed to growing pigs. Pigs were the offspring of Line 359 boars mated to Camborough females (Pig Improvement Company, Hendersonville, TN). In experiment 1, nine growing barrows (initial BW: 55.98 kg ± 13.75 kg) with T-cannulas installed in the distal ileum were allotted to 1 of 3 diets using a triplicated 3 × 3 Latin square design with 3 periods. Two diets were formulated to contain 35% soybean expellers or 33% SBM as the sole source of AA. A N-free diet was used to determine basal endogenous losses of AA. Ileal digesta were collected on days 6 and 7 of each 7-d period. Results indicated that the SID of most indispensable and dispensable AA were greater (P < 0.05) or tended (P < 0.10) to be greater in soybean expellers than in SBM. In experiment 2, a corn-based diet and 2 diets based on corn and each of the 2 soybean products were formulated. Twenty-four growing barrows (initial BW: 44.88 kg ± 2.17 kg) were allotted to 1 of the 3 diets with 8 pigs per diet. Urine and fecal samples were collected for 4 d after 5 d of adaptation. Results indicated that the ATTD of energy and TDF was not different between soybean expellers and SBM, but the ATTD of TDF in the 2 soybean products was greater (P < 0.05) than in corn. Concentrations of DE and ME in soybean expellers were greater (P < 0.05) compared with corn or SBM. Soybean expellers had greater (P < 0.05) calculated NE compared with SBM, but there was no difference in NE between corn and soybean expellers. In conclusion, values for SID of most AA and DE, ME, and NE in soybean expellers were greater than in SBM.