Boar sperm viability, head morphometry, and kinetics during seven-day storage in improvised portable semen shipper

Artificial insemination (AI) is pivotal in sustaining pig reproduction both in backyard and commercial production systems. With AI, boar-for-hire service boars – which are quite popular in backyard pig farming in the Philippines – do not have to be transported over long distances, thus improving efficiency, biosecurity, and productivity. One crucial aspect of a successful distance AI operation is ensuring the timely availability of fresh extended boar semen doses stored in appropriate semen cool boxes (15–18 deg C) to avoid irreversible damage due to cold shock. This study was conducted to objectively determine the viability, head morphometry, and kinematic performance of boar spermatozoa during storage in [a] an improvised portable semen shipper (sSHPR) as compared to [b] standard semen refrigerator (sREF) using various extenders at different storage times. Boar semen (n = 9) was processed into 80-mL dose (approx 37.5 x 106 spz/mL) using four different extenders: T0 = 0.9% NaCl solution, T1A = mid-term extender A, T1B = midterm extender B, and T2 = long-term extender, and semen quality was monitored at different intervals for up to seven days using the Sperm Class Analyzer sup R CASA system. Using mixed factor ANOVA, boar sperm performance generally remained relatively similar between the sREF and sSHPR (p 0.05). Prolonged storage times, however, had a significant effect – particularly toward Days 5 and 7, depending on the extender used. Boar sperm in commercial extenders recorded an average of 78.45 ± 2.23% and 82.85 ± 11.39% total motility for sSHPR and sREF on Day 5, respectively. Velocity parameters (VCL, VSL, VAP) and head width also changed over time. The potential to safely store and preserve extended boar semen using an improvised portable semen shipper described in this study provides an opportunity to further explore this device as an affordable alternative storage system for extended boar semen for research or AI purposes.