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In Feed Formulation, the Input Determines the Output

I received a correspondence from a practicing nutritionist and feed formulator wanting to verify the True Metabolizable Energy (TMEn) of an Extruded-Expelled soybean meal (ExPress® soybean meal) that he is considering for his organic feed formulation. He asked a very legitimate question:

“How can a partially defatted soybean meal containing 6-8% oil have TMEn close to or higher than a full fat ‘soybeans, heat processed seeds’ that has 18% oil in it?”

Throughout the years, I have dealt with numerous questions similar to this one especially on extruded whole soybeans as compared with “soybeans, heat processed seeds” reported in the National Research Council (NRC) nutrient requirement for poultry.

To make it easier on you, please compare the following:

(Energy expressed on dry matter basis)

Here are my explanations:

1. The NRC “Soybeans, heat processed seeds” is a generic terminology that ignores the effect of processing methods on the nutritional values of the soybeans. Heat processed soybeans could be roasted soybeans, micronized, jet sploded, microwaved, toasted, wet extruded or high shear extruded.
2. In our opinion, the listed value is closer to that of roasted whole soybeans than extruded.
3. The NRC value could have been generated by a prediction equation that was based on the chemical analysis that may or may not correlate to an in-vitro or in-vivo trial.
4. If it was correlated to an in-vivo trial, there is a high possibility that the TMEn was not for the high shear (Insta-Pro) extruded soybeans.
5. The Insta-Pro reported TMEn* values are based on in-vivo trials.
6. The oil availability, the increased nutrients digestibility and possible modification of the highly indigestible soy carbohydrates (Oligosaccharides) into more digestible sugars may explain the higher TMEn of the high shear extruded products. The higher metabolizable energy of extruded whole soybeans as compared with other processing techniques has been documented in many in-vivo trials. This higher energy, digestible or metabolizable, is not confined to poultry only, but other animal species.

Does this make sense to you? If not, references on this subject are available upon request.