In poultry feed, extrusion is the best soybean treatment. Actually it allows:
As far as dairy cows are concerned, it is difficult to calculate the energy value of standard extruded soybeans. The French system is UFL (dairy feed unit), commonly calculated using an equation based on raw material composition. But it does not take into account components digestibility or interactions between them. We must find another method of evaluation. INRA has developed truly digestible proteins in the intestine system (DPI) consisting of the sum of:
With this method, it is possible to compare extruded and raw soybeans’ characteristics according to their residence time in the rumen. The longer the residence time of rumen’s soybean increases, the lower is the DPI content, but this is especially true for raw beans -43% against -16% for extruded beans. In addition, extruded beans contain between 45 and 110% more DPI than raw beans. With regard to by-pass proteins, extrusion cooking makes it possible to increase their number between 100 and 300%. These calculations highlight profitability of soybeans extrusion into dairy cows diet.
Because of its high protein content, soy is widely used in animal feed. In order to maximize its value, extrusion is the most appropriate technological treatment whatever species.