High percentage of morphological defects in sperm of the Zemplin rabbit breed: A major obstacle to fertility?

This research investigates the high prevalence of morphological defects in the sperm of a particular rabbit breed, namely the Zemplin rabbit (ZR). We tried to uncover the possible causes and consequences of the observed abnormalities. Ejaculate samples from ten adult males were divided into two qualitative groups according to the motility parameters revealed by CASA (computer-assisted sperm analysis). Group A contained samples with total motility (TM) above 50% and progressive motility (PM) above 30%. Group B contained samples with TM and PM below these values. Viability (SYBR-14/DRAQ5TM and SYTOXTM Green/DRAQ5TM staining) and apoptosis (YO-PRO TM-1/DRAQ5 TM stainig) analyses through flow cytometry served as an additional insight into the characteristics of the qualitative groups. In both cases, we noted significant differences (P < 0.05) between groups which corresponded to motility values. Both groups showed an increased incidence of abnormal spermatozoa, and we did not observe any significant differences between them. Simultaneously, we assessed the practical implications of these sperm defects on artificial insemination (AI), and also, we did not notice any significant differences in these parameters. The use of transmission electron microscopy enhanced our understanding of the morphological defects at the ultrastructural level. In summary, the study provides an understanding of the qualitative differences in rabbit semen, highlighting variations in quality parameters. While these differences exist, they may not necessarily translate into significant variations in AI outcomes. Our study shows higher values of cytoplasmic droplets in ZR semen, but it also shows that these conditions do not necessarily mean a fundamental obstacle to fertility in the case of AI.