Soybean meal is a high quality source of protein in diets fed to pigs. However, soybean meal contains anti-nutritional factors such as trypsin inhibitors and oligosaccharides, which decrease nutrient availability and limit the amount of soybean meal that can be fed in weanling pig diets.

Soy protein concentrate is produced by processing soybean meal to remove some nonprotein components, including the soluble carbohydrates. This leaves soy protein concentrate with a greater concentration of crude protein and amino acids than soybean meal. The presence of oligosaccharides in soybean meal has been shown to reduce the tolerance of young pigs to conventional soybean meal, and therefore, animal proteins rather than soybean meal is often used in diets for young pigs. However, if the oligosaccharides and other antinutritional factors can be removed from soybean meal, it is possible to use soybean meal in diets for young pigs instead of animal proteins.

Typically, an alcohol extraction process has been used to remove soluble carbohydrates from soybean meal to create soy protein concentrate. However, a new source of soy protein concentrate called Nutrivance (Midwest Ag Enterprises Inc., Marshall, MN) has recently been introduced. Nutrivance 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 digestibility of amino acids in this new source of soy protein concentrate.

Nine weanling barrows with an average initial body weight of 13.08 kg were used in the experiment. Pigs were fed one of three cornstarch based diets. Two diets contained soy protein concentrate or conventional soybean meal as the only source of amino acids. These diets were formulated to contain the same amount of protein. The last diet was a nitrogen-free diet that was used to estimate basal endogenous losses of crude protein and amino acids.

Ileal samples were collected and analyzed to determine apparent ileal digestibility (AID) of crude protein and amino acids. The AID values were then corrected for basal endogenous losses to calculate the standardized ileal digestibility (SID).

The concentrations of crude protein and amino acid in soybean meal and soy protein concentrate are shown in Table 1.

The AID of cysteine and glutamic acid was greater (P < 0.05) in soybean meal than in soy protein concentrate (Table 2). The SID of isoleucine, leucine, phenylalanine, proline, and tyrosine was greater (P < 0.05) in soy protein concentrate than in soybean meal. With those exceptions, no differences were observed in the AID or SID of crude protein and amino acids between soybean meal and soy protein concentrate. Although previous experiments have shown amino acid digestibility to be greater in soy protein concentrate than in soybean meal that was not the case in this experiment. This may be due to the different process used to produce the soy protein concentrate in this experiment.

• The procedure used to create soy protein concentrate from soybean meal removes oligosaccharides and increases protein concentration.
• The SID of crude protein and most amino acids in the source of soy protein concentrate used in this experiment did not differ from that in soybean meal.
• Soy protein concentrate may be used instead of soybean meal in diets fed to weanling pigs without negatively affecting SID of amino acids.

Table 1. Crude protein and amino acid content of soybean meal (SBM) and soy protein concentrate (SPC), as fed basis

Table 2. Apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of crude protein and amino acids in soy protein concentrate (SPC) and soybean meal (SBM) by weanling pigs.

^a-bLeast squares means 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.