Soy protein concentrate is produced by aqueous ethanol extraction of water-soluble carbohydrates from soybean meal, followed by heat treatment. The ethanol extraction process removes soluble carbohydrates, leaving a product that contains at least 65% crude protein (dry matter basis). Because soy protein concentrate contains reduced levels of oligosaccharides, trypsin inhibitors, and lectins compared with conventional soybean meal, it can be used in diets for weanling pigs.
Studies have shown that grinding grains to smaller particle sizes increases the digestibility of energy. However, there are no reports on the effect of particle size on energy digestibility in soy protein concentrate. Therefore, an experiment was conducted to determine the concentrations of digestible (DE) and metabolizable (ME) energy in soy protein concentrate ground to three different particle sizes and to compare these values to values for corn, soybean meal, and fish meal when fed to weanling pigs.
Materials and methods
Weanling barrows with an average initial body weight of 13.7 kg were allotted to one of six diets. Three sources of soy protein concentrate were used: X-SOY 80, with a particle size of 80 microns; X-SOY 200 (200 microns); and X-SOY 600 (600 microns). A corn diet was formulated containing 96.7% corn and vitamins and minerals. In the other five diets, 21 to 30% of the corn was replaced with one of the three X-SOY products, soybean meal, or fish meal.
Fecal and urine samples were collected and analyzed to determine DE and ME in the diets. The DE and ME in the protein sources were then calculated using the difference procedure.
Results
On an as-fed basis, the concentration of DE in X-SOY 200 and X-SOY 600 was greater (P < 0.05) than in corn, soybean meal, or fish meal, but was not different from the concentration of DE in X-SOY 80 (Table 1). There was no difference among dietary treatments in ME on an as-fed basis, or in DE or ME on a dry matter basis.
Key points
- Particle size has no effect on concentrations of digestible and metabolizable energy in X-SOY soy protein concentrate.
- On a dry matter basis, X-SOY contains the same amount of digestible and metabolizable energy as corn, soybean meal, and fish meal.
Table 1. Digestible and metabolizable energy concentrations in corn, soybean meal, X-SOY 80, X-SOY 200, X-SOY 600, and fish meal
|
|
Ingredient |
|
|
|||||
|
Item |
Corn |
Soybean meal |
X-SOY 80 |
X-SOY 200 |
X-SOY 600 |
Fish meal |
SEM |
P-value |
|
As-fed basis |
||||||||
|
DE, kcal/kg |
3,407b |
3,618b |
3,750ab |
3,985a |
3,985a |
3,593b |
122 |
< 0.05 |
|
ME, kcal/kg |
3,346 |
3,305 |
3,528 |
3,704 |
3,658 |
3,424 |
144 |
0.291 |
|
DM basis |
||||||||
|
DE, kcal/kg |
3,990 |
4,021 |
3,914 |
4,198 |
4,233 |
3,949 |
132 |
0.41 |
|
ME, kcal/kg |
3,919 |
3,672 |
3,683 |
3,903 |
3,886 |
3,763 |
156 |
0.758 |
a-cWithin a row, means without a common superscript letter are different (P < 0.05).
This report is based on unpublished research by Chengfei Huang and Hans H. Stein.