RESUMO
The effect of seminal plasma (SP) on the motility, capacitation status, penetration through cervical mucus and fertility of frozen-thawed ram spermatozoa was examined. In the presence of SP, motility of frozen-thawed spermatozoa was better (P<0.001) and there were more uncapacitated and less acrosome-reacted cells in comparison with controls (P<0.001). Frozen thawed spermatozoa were also better able to penetrate cervical mucus after addition of SP. Addition of SP increased the percentage of ewes pregnant after insemination of frozen-thawed (39/94, 41.5% v. 51/92, 55.4%; P<0.05) but not fresh spermatozoa (34/55, 61.8% v. 42/58, 72.4% for 0 v. 30% SP in the resuspension medium). Moreover, SP improved pregnancy rates after cervical (14/50; 28% v. 25/49; 51%; P<0.05) but not intrauterine insemination (25/44; 56.8 v. 26/43; 60.5%) with frozen-thawed spermatozoa. In a second experiment, pregnancy rates were 30/45 (66.7%), 9/37 (24.3%) and 24/40 (60.0%) for ewes inseminated with frozen-thawed spermatozoa in the uterus (control), cervix without SP and cervix after supplementation with SP, respectively (P<0.01 for unsupplemented v. supplemented spermatozoa). These experiments demonstrate that impaired function of cryopreserved spermatozoa can be overcome by addition of SP, resulting in normal fertility after cervical AI.