Distinct seminal plasma protein profiles reveal molecular signatures of semen freezability in Malabari bucks

Abstract

The cryopreservation of semen remains a cornerstone of genetic improvement in goat breeding, yet its success is highly variable. This variability is poorly understood but is thought to be influenced by the molecular composition of seminal plasma. This study aimed to characterize the seminal plasma protein profile of Malabari bucks with high and low semen freezability using SDS-PAGE. Semen was collected from six bucks and classified based on post-thaw progressive motility into High Freezability (HF, ?35% motility) and Low Freezability (LF, <30% motility) groups. Electrophoretic analysis revealed stark differences between groups. The LF group exhibited a complex profile with 57 unique protein bands, prominently featuring high molecular weight proteins (>150 kDa). In contrast, the HF group demonstrated a more refined proteome with only 33 unique bands, dominated by lower and mid-range molecular weight proteins. This clear divergence in protein profiles establishes seminal plasma composition as a key determinant of cryotolerance and provides a foundational protein signature for predicting semen freezability, offering a practical tool for improving caprine breeding programs.