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 apparent total tract digestibility (ATTD) of GE and total dietary fiber (TDF) and DE and ME concentrations in the soybean expellers that are produced from this procedure. Therefore, the objective of this research was to test the hypothesis that the ATTD of GE and TDF and concentrations of DE and ME are greater in soybean expellers than in SBM when fed to growing pigs.
Experimental design
Twenty-four growing barrows (initial body weight: 44.88 ± 2.17 kg) were allotted to 3 diets and thus there were 8 replicate pigs per diet. Urine and fecal samples were collected for 4 d after 5 d of adaptation. A corn-based basal diet and 2 diets containing corn and soybean expellers or corn and SBM were formulated thus a total of 3 diets were used.
Results
On an 88% dry matter basis, GE in soybean expellers was greater than in SBM, mainly because of greater fat concentration in soybean expellers (Table 1). The ATTD of GE and TDF was not different between the 2 soybean products (Table 2). Concentrations of DE and ME in soybean expellers were greater (P < 0.05) compared with corn or SBM.
Key points
- Soybean expellers have greater concentrations of DE and ME compared with SBM.
- There was no difference in the ATTD of TDF between the 2 soybean products.
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 |
|
Acid-hydrolyzed ether extract |
6.66 |
2.90 |
|
TDF |
19.50 |
20.60 |
|
d |
d |
d |
1All values except dry matter were adjusted to 88% dry matter.
Table 2. Energy and GE and TDF digestibility and concentrations of DE and ME in soybean expellers and SBM fed to growing pigs (as-fed basis)
|
Item |
Soybean expellers |
SBM |
SEM |
P-value |
|---|---|---|---|---|
|
ATTD, % |
|
|
|
|
|
GE |
88.1 |
83.2 |
2.10 |
0.126 |
|
TDF |
80.2 |
82.7 |
3.37 |
0.604 |
|
DE, kcal/kg, as-fed |
4,023 |
3,465 |
92 |
< 0.001 |
|
ME, kcal/kg, as-fed |
3,853 |
3,248 |
98 |
< 0.001 |
|
x |
x |
x |
x |
x |