Benefits of processing soy meal compared to solvent extracted.
A horizontal, mechanical oil press to be used immediately after the extruder for crude oil isolation. Interestingly, this chemical-free extraction process produces oil with different, beneficial properties when compared to solvent-extracted soy oil.
The result of including the oil press after the extruder is that a unique soy meal is produced – one that has highly-digestible amino acids and a greater metabolizable energy content, due to a residual oil content in the meal of 6-8%, and also because the dry extrusion process liberates more available energy.
Soy meal in the laboratory tested for determination of amino acid digestibilities and metabolizable energy using broiler chickens. Nutritionists and formulators rely on these values when assembling diets. Values for samples of commodity, solvent-extracted soybean meal, which were also recently analyzed, are shown for comparison.
Digestible AA supply and % digestibility soy meal Solvent-extracted soybean meal
Digestible lysine 2.54 (88.7%) 2.68 (87.5%)
Digestible methionine 0.54 (90.6%) 0.62 (91.2%)
Digestible cysteine 0.48 (83.4%) 0.50 (77.8%)
Digestible threonine 1.44 (87.9%) 1.61 (85.9%)
Digestible tryptophan 0.66 (97.1%) 0.71 (96.1%)
True metabolizable energy, nitrogen corrected (kcal/kg DM) 3385 2796
Dry matter (%) 96.6 89.1
Several things are apparent. Overall, soy meal is more digestible than solvent-extracted soybean meal. However, it’s important to remember that this is only true when extrusion is conducted at the proper temperature. Quality controls, such as monitoring temperature during runs, are crucial, and allow meal to stand out from other ingredients which are more variable.
The residual oil and processing benefits associated with meal result in a higher metabolizable energy value – typically this means that an additional energy source, such as AV blends or spent oils, is not required.