By Warren Rusche
Introduction
Distillers grains (DGS) have been the primary source of supplemental protein in cattle diets for more than twenty years. As ethanol production ramped up in the Corn Belt, DGS became a widely available and favorably priced alternative to other protein sources and quickly took the position as the default protein source. In fact, many cattle feeders and nutritionists have never worked in a world where feeding DGS was not the norm.
However, agriculture rarely remains static. At one time, DGS were priced at a significant discount to corn, now those feedstuffs are usually priced at nearly the same cost per unit of dry matter. The cattle being fed have also changed. Cattle today grow faster, have improved marbling, and are marketed at heavier weights compared to when DGS were first studied. Assuming that the best answer from yesterday is still true today risks missing opportunities. For those reasons, the SDSU Feedlot Research group has been re-examining whether soy protein fits into modern cattle feeding diets.
What Is Unique About Heat-Treated Soybeans?
Heat-treated soybeans offer interesting attributes that could enhance cattle growth. Applying heat to a feed can alter structures, resulting in reduced degradation in the rumen and potentially greater absorption of intact proteins in the small intestine. Soy-based protein contains more lysine compared to corn, so increasing the supply of this essential amino acid could increase cattle growth. In addition, including soybeans in cattle diets increases energy density because of the oil in soybeans. Increased energy concentration from fat results in greater feed efficiency.
Heat-treated soybeans can be differentiated based on how much oil remains in the feed. Roasting uses heat to affect protein structure, but all the oil is retained. Extrusion uses a screw mechanism inside a barrel to create heat and pressure, resulting in ruptured plant cells and altered protein structures. This product can be pressed to extract a portion of the oil (expeller processed) or can be fed as a full-fat product.
Source : sdstate.edu