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. 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.
Reducing the particle size of soybean meal can increase amino acid digestibility due to the increased surface area for enzymes to work on. However, there are no known data on the effect of particle size on amino acid digestibility in soy protein concentrate. Therefore, an experiment was conducted to determine the digestibility of crude protein and amino acids in soy protein concentrate ground to three different particle sizes and to compare these values to values for soybean meal and fish meal when fed to weanling pigs.