Motility and motility parameters of sperm derived from epididymis in young Hanwoo bull ABSTRACT It has been believed that semen collected from less than 15 months of age in bulls have low quality. However, bulls’ abilities (sexual maturity and weight) have been improved by selection of bulls. Thus, the appropriate period of semen collection from bulls’ age should be confirmed. Therefore, we examined sperm motility derived from epididymis in Hanwoo bull at 13 months of age (puberty) to confirm the sperm quality of before freezing and frozen-thawed semen. Collected semen from epididymis of one bull was cryopreserved in LN2. Motility and motility parameters of before freezing and frozen-thawed sperm were examined by Computer Assessment of Sperm Analysis (CASA) system. Percentage of progressive motility of frozen-thawed sperm in epididymis was lower than that of before freezing of sperm (21.2 vs %, respectively). Curvilinear velocity (VCL), straight-line velocity (VSL), average path velocity (VAP) of frozen-thawed sperm derived from epididymis were lower than those of before freezing of sperm (56.1, 18.5, 29.6 vs. 96.4, 31.7, 48.1 µm/sec, respectively). In conclusion, frozen-thawed sperm derived from epididymis in pre-puberty of Hanwoo bull has low motility and many have low sperm motility parameters compared to before freezing of sperm. Thus, further investigation is needed to improve the motility of frozen-thawed sperm derived from epididymis of pre-puberty Hanwoo. Key Words) Bull, Epididymis, Hanwoo, Sperm motility Treatment (replicate) Progressive motile (%) VCL (µm/sec) VSL (µm/sec) VAP (µm/sec) LIN (%) STR (%) WOB (%) ALH (µm) BCF (Hz) 21.2± ± ± ± ±2.4 Table 1. Sperm motility and motility parameters of frozen-thawed semen derived from epididymis in a Hanwoo bull at 13 months of age After thawing (5) 62.4± ±2.12.5± ± Before freezing (1) Mean ± standard deviation (SD). Frozen-thawed semen of epididymis derived from a one bull was used. *Control; commercial frozen-thawed semen from a one bull was used. Progressive motile, VCL, VSL, VAP After thawing; control *(1) Frozen-thawed sperm derived from epididymis Similar motility parameters to commercial sperm Bull testis Sperm recovery in testis derived from castarated bull (13 months) Epididymis Chopping tail of epididymis & Filtering (100 um nylon mesh) Loading to 0.5 ml straw & Cryopreservation Thawed at 37°C for 40 sec LN 2 Cryopreservation & Thawing Dilution (40~80 x 10 6 cells/ml) Evaluation of sperm motility and motility parameters Extender (OptixCell, IMV) Semen derived from sire (14 to 18 months of age) can be used for artificial insemination (Macmillan et al., 1972). Sperm Straight line Velocity (VSL) Average Path Velocity (VAP) Curvilinear Velocity (VCL) Amplitude of Lateral Head (ALH) Beat/Cross Frequency (BCF(Hz)) LIN = VSL / VCL Similar sperm motility compared to commercial semen : Can be used for artificial insemination or in vitro production of embryos Frozen-thawed sperm from epididymis in a young bull Decreased sperm motility : Improvement of freezing procedure Evaluation of sperm characteristics : Acrosomal membrane, mitochondrial membrane potential etc. Evaluation of sperm ability (fertilization ability) Sperm Class Analyzer (CASA, Microoptic, Spain) (x100) Breeding soundness examination periods : 13 months of age (Christin, 1999). head tail body Deferent duct Tail of epididymis STR = VSL / VAP WOB = VAP/VCL Christin B. & Bryan A. R., 1999, Developing young bull, Florida Beef Cattle Short Course, Bull physiological and sexual maturation conditions might be changed by changed feeding system and improvement of bull condition (Taylor, 1994). Therefore, we examined sperm motility in epididymis of young bull (Hanwoo). A young bull semen has similar motility compared to commercial semen? Macmillan K. L., Newhook C. & Watson J. D., 1972, Testicular and epididymal sperm numbers in young Fresian bulls, N. Z. Journal of Agricultural Research, 15: Taylor, R. E., 1994, Beef production and management decisions, Macmillan Publishing Company