Factors Influencing the Sperm Motility and Viability Parameters of Post-Thawed Semen of Tunisian Arab Stallions

The study was taken to investigate the quality of post-thawed semen and to determine factors that can affects semen motility and viability parameters of Tunisian Arab stallions. 42 ejaculates from 9 stallions (young stallions: age < 15 years, n = 5; old stallions: age ≥ 15 years, n = 4) were collected and frozen. After thawing, sperm motility including percentage of total motile sperm (%TMO), percentage of progressive sperm (%PROG), average path velocity (VAP, µm/s), straight line velocity (VSL, µm/s), and curvilinear velocity (VCL, µm /s) were determined. Sperm viability was studied by eosin-nigrosin stain. The results showed that the sperm motility parameters and the percentage of live sperm (%LS) varied between individual stallions (p<0.01). The age of stallions influenced the %PROG (9 ± 0.9% for young vs 7 ± 0.8%; p< 0.05) and the VSL (79 ± 1.7 µm /s for young to 71 ± 2.1 for old; p<0.01). It seems that age, stallion and ejaculate are the main factors influencing the quality of thawed semen of stallion. Other factors related to the freezing process which they have not been considered in this study could be apart of the variation of semen quality.