There are only minor differences among soybeans grown in different areas of the United States in nutrient composition and digestibility of amino acids by growing pigs

Abstract

An experiment was conducted to determine the chemical composition of full-fat soybeans (FFSB) from different regions of the United States (source 01, 02, 03, 04, and 05) and to test the hypothesis that there is no difference in the standardized ileal digestibility (SID) by growing pigs of crude protein (CP) and amino acids (AA) among FFSB sources regardless of where in the United States they were grown. The ground soybeans were extruded and analyzed for dry matter, gross energy, nitrogen, AA, acid-hydrolyzed ether extract, ash, minerals, starch, insoluble dietary fiber, soluble dietary fiber, sugars, and trypsin inhibitors. In the SID experiment, each source of FFSB was included in one diet as the only source of AA and a N-free diet was formulated to determine basal endogenous losses of AA; thus, a total of six diets were prepared. Six growing barrows (initial body weight: 85.50 ± 3.34 kg) that had a T-cannula installed in the distal ileum were allotted to a 6 × 6 Latin square design with six diets and six 7-day periods. Ileal digesta were collected from the cannulas on days 6 and 7 of each period and SID of CP and AA was calculated. Results indicated that the main nutrients in FFSB were CP, acid-hydrolyzed ether extract, and insoluble dietary fiber with an average of 338.0, 171.9, and 176.4 g per kg, respectively. The FFSB also contained an average of 10.3 g per kg starch, 112.5 g per kg sugars, 54.4 g per kg ash, and 21.3 MJ per kg gross energy. The unanalyzed rest fraction in FFSB was 20.6 g per kg on average. Results from the SID experiment demonstrated that there were no differences among the five sources of FFSB for the SID of CP and AA, except that the SID of Glu in FFSB source 02 was greater (P < 0.05) than in FFSB source 01. There was also a tendency (P < 0.10) for the SID of Arg, Gly, and Tyr to be greater in FFSB source 02 compared with FFSB source 01 and the SID of Tyr in FFSB source 02 also tended (P < 0.10) to be greater than in FFSB sources 04 and 05. In conclusion, only minor differences in chemical composition among five sources of FFSB grown in different regions of the United States were observed and the SID of CP and the majority of indispensable AA were not different among the five sources indicating that growing region does not affect digestibility of AA in FFSB.