Benefits of extruded soy for livestock

In poultry feed, extrusion is the best soybean treatment. Actually it allows:

• a better energy rate, increasing by 32% compared to raw seeds, 13% compared to toasted seeds but also more than 6% compared to infrared treatment.
• A total destruction of the cell’s walls that contain the oil, making it available to attack digestive enzyme.
• Optimum preservation of the biological protein value by dry extrusion, thanks to a progressive temperature rise while descent is instantaneous allowing proteins to reach 150°C for less than 3 seconds.
• A 90% antitrypsic factors destruction, responsible for raw seeds bad digestibility.
• Does not affect triglycerides structure (fat). Indeed the maximum temperature of 150°C is lower than fat decomposition temperature (more than 180 ° C), which makes them available for animals. In particular, it contains an interesting content of Omega 6 (linoleic acid): about 10% of the raw product, as well as Omega 3 (linolenic acid), which is particularly profitable for laying hen.
• Good preservation thanks to their low moisture content and lipolytic enzymes destroyed by extrusion.

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:

• Food proteins that have passed through the rumen without modification: by-pass proteins (DPIA)
• Proteins elaborated in the rumen by microorganisms (DPIM)

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.