Effect of donkey seminal plasma on sperm movement and sperm–polymorphonuclear neutrophils attachment in vitro

To evaluate the effect of seminal plasma in endometrial inflammation in donkeys, samples from fresh pure, fresh diluted and frozen-thawed semen of three different jackasses were co-incubated in water bath at 37 °C with uterine Jennie's secretions collected 6 h after artificial insemination with frozen-thawed donkey semen. Individual sperm movement parameters using the computerised sperm analysis system (CASA) and sperm–polymorphonuclear neutrophils (sperm–PMN) attachment observed in Diff-Quick stained smears were evaluated at 0, 1, 2, 3 and 4 h of co-incubation. Controls consisted of incubating diluted or frozen-thawed sperm in the absence of uterine secretions. For data analyses, a repeated measures ANOVA was performed with incubation time as intra-subject factor and with treatment and donkey as inter-subject factor, followed by a post-hoc Bonferroni's test. Greater values (P < 0.05) of sperm–PMN percentages and a loss of progressive motility were observed in frozen-thawed semen compared with pure and diluted fresh semen samples throughout the incubation time. In addition, the presence of seminal plasma in fresh and diluted semen samples reduced the inflammatory response of polymorphonuclear neutrophils produced after insemination by suppressing the sperm–PMN attachment in vitro. Motility sperm parameters analysed by CASA were also less affected than those in frozen-thawed semen samples. In conclusion, seminal plasma in jennies appears to have a modulation on the endometrial response after artificial insemination with frozen-thawed donkey semen. As a result, spermatozoa with the greater motility characteristics are selected.