Enhancing the nutritional value of soybeans for poultry through supplementation with new-generation feed enzymes

Soybean meal (SBM) remains the most important and preferred protein feed source for poultry. However, the supply and quality of SBM fluctuates, and the meal is expensive due to processing and transportation costs. Although there is a growing interest in the use of raw SBM for birds, its nutritive value is negatively affected by the presence of anti-nutritive factors (ANF). Heat treatment is applied to alleviate some ANF, such as trypsin inhibitors and lectins, but both under- and over-processing of soybeans can reduce the digestibility of key components in the meal. Feed supplementation with exogenous enzymes, such as phytase and protease enzymes, is a biotechnological option for improving the nutritional values of SBM and other protein-rich ingredients. Proteases break down both stored proteins and proteinaceous anti-nutrients in feeds. Various studies have shown that the performance of birds can be improved through dietary supplementation with new-generation protease enzymes. Phytase is also effective in breaking down phytate (phytic acid), which chelates with mineral cations and other nutrients in soybeans. Recent in vitro and in vivo studies have shown that an enzyme cocktail (combined use of protease and phytase) is more effective in reducing ANF in soybean meal for birds than the use of single enzyme products. This review provides information on how microbial enzymes, particularly protease and phytase, contribute to the improvement of the nutritional values of different types of SBM for poultry.