Optimizing Boar Epididymal Sperm Preservation: Comparative Analysis of Slicing Float-Up vs. Flushing and BTS vs. Andromed® Extenders on Sperm Motility and Morphometry Traits

Abstract

Epididymal sperm collection represents a valuable strategy for preserving genetics from deceased or castrated boars of superior breeding value. The two primary collection methods-slicing float-up (high sperm yield) and flushing (low blood contamination risk)-differ in sperm recovery efficiency, while semen extenders provide cryoprotective nutrients that protect against cold shock during preservation. This study compared the effects of slicing float-up versus flushing collection methods and Beltsville Thawing Solution (BTS) versus Andromed® extenders on motility and morphometric characteristics of boar epididymal sperm. Epididymides were collected from 40 testes obtained at a local slaughterhouse and processed within 30 minutes post-slaughter at 5°C. Sperm retrieved from the cauda epididymis were diluted with BTS or Andromed® and analyzed using computer-assisted sperm analysis (CASA) for motility assessment and morphometric evaluation. The flushing-Andromed® combination produced the lowest total (29.7%), progressive (4.9%), and rapid (1.24%) motility values. Conversely, slicing float-up with BTS yielded the highest total (85.0%), progressive (57.7%), and rapid (31.8%) motility. Andromed® treatment induced decreased sperm head diameter and acrosomal morphology alterations, consistent with premature acrosome reaction, thereby reducing sperm head dimensions. Sperm head morphometric parameters remained within acceptable reference ranges across all treatment groups (length: 8.2-8.9 µm; perimeter: 18.2-19.9 µm; width: 4.1-4.6 µm; area: 34.8-38.6 µm²). These findings recommend slicing float-up with BTS extender as the optimal protocol for boar epididymal sperm collection and short-term preservation, with implications for swine genetic resource conservation.