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Germination and extrusion modify ruminal degradation kinetics and protein subunit profiles of soybean seeds

Year: 2026

Type: preprint

Abstract: The present study examined how dry matter (DM) and crude protein (CP) from raw, germinated, and extruded whole soybeans are broken down within the rumen over time. Using the in situ nylon bag approach alongside SDS‑PAGE, we followed how the protein subunits were altered throughout the experiment. Soybean specimens, whether raw or processed, were placed in nylon pouches and incubated within the rumen of three Holstein steers across timepoints spanning 0, 2, 4, 8, 16, 24, and 48 hours. A non-linear modeling approach was applied to the degradation results to compute effective ruminal degradability (ERD). Notable differences ( P < 0.05) emerged in DM and CP degradation metrics between raw and extruded soybeans. Extrusion processing lowered the rapidly soluble crude protein fraction and increased the slowly degradable fraction, which led to a statistically significant decline ( P < 0.05) in the effective degradability of crude protein. Densitometric quantification confirmed that β -conglycinin and glycinin represent the two dominant protein classes in soy. According to SDS-PAGE analysis of residual protein, the α and α′ subunits of β -conglycinin were entirely degraded between 2 and 48 hours of ruminal incubation, while the β subunit exhibited greater resistance to breakdown. In raw soybeans, glycinin's acidic and basic polypeptides were digested during mid-incubation phases; in contrast, extrusion allowed these subunits to persist largely unaltered for up to 48 hours within the rumen. In conclusion, the electrophoretic evidence indicated that the ruminally undegradable protein fraction of raw soybeans consisted chiefly of glycinin's basic subunit, while in extruded samples it was comprised mainly of β -conglycinin alongside both acidic and basic glycinin subunits.

Source: Research Square

DOI: 10.21203/rs.3.rs-9930249/v1

Authors: Amir Reza Habibi, Mohammad Chamani, Farhad Foroudi, Ali Asghar Sadeghi

Institutions: Islamic Azad University, Tehran, Islamic Azad University of Varamin

Language: English

Topic: Ruminant Nutrition and Digestive Physiology

Subfield: Animal Science and Zoology

Field: Agricultural and Biological Sciences

Domain: Life Sciences

SDG: Zero hunger

Open Access status: green

Funder: Islamic Azad University