When soybeans are crushed, the oil may be solvent extracted and the resulting defatted soybeans are known as soybean meal (SBM). However, the oil may also be mechanically expelled from the beans and the defatted soybeans resulting from this procedure is an ingredient known as soybean expellers. The expelling procedure is less efficient in removing oil from the beans and soybean expellers, therefore, contain more residual oil than SBM. Soybean expellers can be produced using different technologies, and a new procedure involving a patented high shear dry extrusion procedure was recently developed (Insta-Pro International, Des Moines, IA). There are however, no data for the digestibility of amino acids (AA) in the soybean expellers that are produced from this procedure. Therefore, the objective of this research was to test the hypothesis that the standardized ileal digestibility (SID) of crude protein (CP) and AAis greater in soybean expellers than in SBM when fed to growing pigs.
Experimental design
Nine growing barrows (initial body weight: 55.98 kg) with a T-cannula in the distal ileum were allotted to a triplicated 3 × 3 Latin square design with 3 diets and 3 periods. Ileal digesta were collected on d 6 and 7 of each 7-d period.
One diet was formulated to contain 35% soybean expellers as the sole source of AA, and one diet was formulated to contain 33% SBM as the sole source of AA. A nitrogen-free diet that was used to determine basal endogenous losses of AA from the pigs was also formulated.
Results
On an 88% DM basis, soybean expellers contained more GE and acid hydrolyzed ether extract, but less CP and similar TDF concentration compared with SBM (Table 1).
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 compared with SBM (Table 2).
Key points
- A new source of soybean expellers contains more GE, fat, and less CP compared with non-dehulled SBM.
- Values for SID of most AA in soybean expellers were greater than in SBM.
Table 1. Nutrient composition of soybean expellers and SBM1
|
Item, % |
Soybean expellers |
SBM |
|---|---|---|
|
Dry matter |
93.28 |
92.42 |
|
GE, kcal/kg |
4,631 |
4,141 |
|
CP |
43.36 |
45.25 |
|
Acid-hydrolyzed ether extract |
6.66 |
2.90 |
|
TDF |
19.50 |
20.60 |
|
s |
s |
s |
1All values except DM were adjusted to 88% DM.
Table 2. Standardized ileal digestibility (%) of amino acids in soybean expellers and SBM fed to growing pigs
|
Item |
Soybean expellers |
SBM |
SEM |
P-value |
|---|---|---|---|---|
|
CP |
91.2 |
88.5 |
1.07 |
0.078 |
|
Arg |
97.6 |
94.4 |
0.79 |
0.002 |
|
His |
94.4 |
91.2 |
0.66 |
0.003 |
|
Ile |
93.4 |
89.5 |
1.04 |
0.019 |
|
Leu |
93.4 |
89.6 |
0.88 |
0.013 |
|
Lys |
92.0 |
88.6 |
1.18 |
0.059 |
|
Met |
93.8 |
90.7 |
0.97 |
0.034 |
|
Phe |
94.1 |
90.0 |
0.90 |
0.010 |
|
Thr |
91.4 |
87.7 |
1.20 |
0.045 |
|
Trp |
94.9 |
93.6 |
0.65 |
0.092 |
|
Val |
92.6 |
88.4 |
1.11 |
0.021 |
|
x |
x |
x |
x |
x |