Assessment of semen quality in Swamp Buffalo AI Bulls in Thailand

Abstract

Characteristic of Thai swamp buffalo bulls semen used for artificial insemination (AI) in Thailand, aspects relevance in freezing and thawing of semen are review. Semen and sperm characteristics were evaluated included sperm count, motility (assessed subjectively and by CASA), morphology (using phase-contrast light microscopy and SEM), plasma membrane integrity (PMI) (using a hypo-osmotic swelling test [HOST]) and SYBR- 14/propidium iodide [PI]), plasma membrane stability (PMS) (using Annexin-V/PI) and deoxyribonucleic acid (DNA) integrity (using SCSA and flow cytometry [FCM]). The average ejaculate volume was about 3.0-4.0 mL, with good viability (PMI measured by the HOST) and motility (>65% and >70%, respectively). Sperm concentration ranged from 1.1 to 1.2 billion/mL, being also affected by bull age. Whereas semen quality (including sperm output, pH and initial sperm motility) did not differ between the seasons. Few spermatozoa (<15%/ ejaculate) had abnormal morphology with abnormalities resembling those in other bovidae. In FT semen, PMI (using SYBR-14/PI) and PMS were highest in winter. Across seasons, ~50% of post-thaw spermatozoa depicted linear motility, a proportion that decreased to ~35% during incubation (38°C for 60 minutes), without marking any seasonal difference. The sperm DNA was hardly damaged (with <3% fragmentation, expressed as DNA fragmentation index [DFI]), among seasons.