Abstract Objective To evaluate different processing methods on the liquefaction of the coagulum from semen collected in the bonobo ( Pan paniscus ). Methods In this experimental cross-sectional study, ejaculates voluntarily collected were divided among 4 processing methods and evaluated for subjective total and progressive motility, numbers of total and progressively motile spermatozoa per ejaculate, and morphology. Data were assessed for normality using a Shapiro-Wilk test and subsequently tested for between-group differences using a Kruskal-Wallis test, with significance set at P < .05. Results A total of 22 ejaculates collected from 3 males were divided among 4 groups: passive liquefaction (PL; n = 6), HEPES-balanced salt solution (4), trypsin enzymatic digestion (6), and colloidal centrifugation (CC; 6). The PL and CC groups showed the highest subjective mean total (43.3 ± 31.25% and 51.7 ± 32.81%) and progressive motility (35.0 ± 28.28% and 45.8 ± 30.07%), both of which were significantly greater than the HEPES-balanced salt solution group (0%). No method significantly surpassed the others in either the total or the progressively motile number of spermatozoa. The PL and CC groups also showed significantly higher percentages of normal morphology (60.67 ± 9.65% and 58.67 ± 13.97%, respectively) compared to the trypsin enzymatic digestion group (30.5 ± 8.87%). Conclusions PL and CC processing methods produced ejaculates with the highest subjective total and progressive motility and normal morphology upon microscopic evaluation. Clinical Relevance This study suggests that the processing methods of passive liquefaction and colloidal centrifugation may be most efficacious for preserving bonobo spermatozoa motility and morphology.
Dziubinski et al. (2026) studied this question.