Effect of seminal plasma on cryopreservation and function of bovine spermatozoa

This study was conducted to :1) determine the effect of seminal plasma (SP) on sperm viability parameters (estimated percent motile sperm, computer-aided percent motile sperm and percent intact acrosomes) and motion characteristics (average path velocity, VAP; curvilinear velocity, VCL; and straight line velocity, VSL) of cryopreserved ejaculated spermatozoa (Experiment 1) and cauda epididymal spermatozoa, both fresh and frozen (Experiment 2).2) determine the effect of additional SP on sperm transport in the female using cryopreserved ejaculated sperm (Experiment 3) or cryopreserved cauda epididymal sperm (Experiment 4). In Experiment I, addition of SP (1:1, v/v, post-thaw) did not affect (P> .05) viability parameters; however, all sperm motion characteristics were improved at 3 h of incubation (P < .05). In Experiment 2, addition of a normal complement of SP to cauda epididymal sperm significantly improved all motion characteristics and viability parameters except acrosomal integrity (P < .05) and semen freezing did not alter this effect. In Experiment 3 and 4, addition of SP to the inseminate did not affect the mean or median accessory sperm number (P> .05); however, in both experiments there was a trend toward increased median accessory sperm values for the SP-treated semen. In Experiment 3, mean ± SD and median accessory sperm values per embryo/ovum were 19.2± 36.9 and 2.5 for the control (n = 32); and 23.1 ± 71.6 and 6.5 for the treatment (n = 32). In Experiment 4, mean± SD and median accessory sperm values per embry%vum were 9.2± 16.7 and 1.0 for the control (n = 30); and 14.2± 21.2 and 3.5 for the treatment (n = 30). We conclude from these experiments that sperm motion characteristics but not viability parameters of ejaculated frozen-thawed semen are improved by additional SP (Experiment 1) and both motility and motion characteristics are modestly improved by a normal complement of SP added to cauda epididymal sperm (Experiment 2). This positive effect of SP on motility/motion characteristics may favor sperm transport, but not at a statistically significant level to be detected by accessory sperm number.