Soybean meal is the main protein source used in diets for pigs in the United States, as well as most countries of the world, due to the high quality of the protein it provides. However, soybean meal also contains antinutritional factors that limit its use in weanling pig diets. Pigs do not secrete the enzyme needed for the hydrolysis of raffinose and stachyose, α-galactosidase, in the small intestine. Therefore, these oligosaccharides are not enzymatically digested, but are instead fermented in the small and large intestines. This results in decreased growth performance and increased incidence of diarrhea when fed to weanling pigs.
Oligosaccharides can be removed from soybean meal using an alcohol extraction process, creating soy protein concentrate. Soy protein concentrate has greater digestibility of most amino acids and greater concentrations of digestible energy (DE) and metabolizable energy (ME) than soybean meal. A new source of soy protein concentrate called Nutrivance (Midwest Ag Enterprises Inc., Marshall, MN) has recently been introduced, which is produced using a process combining non-alcohol extraction and enzymatic treatment of soybean meal. The nutritional value of soy protein concentrate produced using this method has not been determined. Therefore, an experiment was conducted to determine the concentrations of DE and ME in soy protein concentrate and to compare these values to DE and ME in soybean meal.
Experimental design
Twenty-four barrows with an average initial body weight of 13.94 kg were used for the study. Pigs were fed one of three diets: a basal diet containing 96.9% corn, a diet containing 61.4% corn and 36% soybean meal, and a diet containing 70.3% corn and 27.0% soy protein concentrate (all diet compositions expressed on as-fed basis).
After a five-day adaptation period to the diets, feces and urine were collected and their energy content analyzed to calculate the DE and ME for each diet. The contributions of DE and ME from corn to the diets containing soy protein concentrate or soybean meal were then calculated, and the concentrations of DE and ME in soy protein concentrate and soybean meal were calculated by difference.
Soy protein concentrate contains more digestible and metabolizable energy than soybean meal
The nutrient composition of the three tested ingredients is shown in Table 1. Processing soybean meal into soy protein concentrate resulted in the removal of almost all the low-molecular weight carbohydrates (sucrose, maltose, stachyose, and raffinose). As a consequence, the concentration of crude protein and amino acids was increased in soy protein concentrate compared with soybean meal.
The apparent total tract digestibility (ATTD) of gross energy (GE) was not different between corn and soy protein concentrate, and greater (P < 0.05) in corn than in soybean meal (Table 2). On both an as-fed and a dry matter basis, the concentrations of DE and ME were greatest (P < 0.01) in soy protein concentrate compared with corn and soybean meal. On a dry matter basis, soybean meal contained more DE than corn, but the concentration of ME was not different between corn and soybean meal.
Key points
- Processing of soybean meal with a novel process using non-alcohol extraction and enzymatic treatment reduces the concentrations of oligosaccharides that are not enzymatically digested by young pigs. Therefore, the concentration of nutrients from which pigs are able to derive energy is increased.
- Soy protein concentrate produced using this novel method has greater concentrations of DE and ME than corn or soybean meal.
Table 1. Nutrient composition of corn, soybean meal (SBM), and soy protein concentrate (SPC), as fed-basis
|
|
Ingredient |
||
|
Item |
Corn |
SBM |
SPC |
|
DM,% |
87.47 |
84.93 |
92.10 |
|
GE, kcal/kg |
3,765 |
4,133 |
4,636 |
|
CP,% |
7.18 |
47.67 |
61.21 |
|
Total AA, % |
3.63 |
22.79 |
29.09 |
|
AEE1, % |
3.94 |
1.56 |
1.79 |
|
NDF,% |
6.58 |
6.45 |
8.87 |
|
ADF,% |
2.17 |
6.78 |
6.19 |
|
Starch,% |
72.8 |
ND2 |
2.7 |
|
Ash, % |
6.77 |
1.24 |
4.06 |
|
Carbohydrates, % |
|||
|
Glucose |
0.2 |
0.0 |
0.0 |
|
Sucrose |
1.57 |
9.20 |
0.97 |
|
Maltose |
ND |
0.18 |
ND |
|
Fructose |
0.15 |
ND |
ND |
|
Stachyose |
ND |
6.07 |
0.76 |
|
Raffinose |
0.21 |
0.95 |
0.15 |
1AEE = acid hydrolyzed ether extract.
2ND = not detectable.
Table 2. Concentrations of DE, ME and apparent total tract digestibility in corn, soybean meal (SBM), and soy protein concentrate (SPC) fed to pigs
|
|
Ingredient |
|
|
||
|
Item |
Corn |
SBM |
SPC |
SEM |
P-value |
|
ATTD, GE % |
89.05a |
85.49b |
87.31ab |
1.05 |
<0.05 |
|
As-fed basis |
|||||
|
DE, kcal/kg |
3,369b |
3,474b |
4,116a |
54.55 |
<0.01 |
|
ME, kcal/kg |
3,271b |
3,014c |
3,701a |
73.48 |
<0.01 |
|
DM basis |
|||||
|
DE, kcal/kg |
3,851c |
4,090b |
4,469a |
61.77 |
<0.01 |
|
ME, kcal/kg |
3,739b |
3,549b |
4,019a |
82.55 |
<0.01 |
a-cLeast squares within a row lacking a common superscript letter are different (P < 0.05).
This report is based on unpublished research by Maryane Sespere Oliveira and Hans H. Stein.