Validation of a portable device (iSperm® ) for the assessment of stallion sperm motility and concentration

The future of equine semen analysis

We are currently experiencing a period of rapid advancement in various areas of science and technology. The integration of high throughput 'omics' techniques with advanced biostatistics, and the help of artificial intelligence, is significantly impacting our understanding of sperm biology. These advances will have an appreciable impact on the practice of reproductive medicine in horses. This article provides a brief overview of recent advances in the field of spermatology and how they are changing assessment of sperm quality. This article is written from the authors' perspective, using the stallion as a model. We aim to portray a brief overview of the changes occurring in the assessment of sperm motility and kinematics, advances in flow cytometry, implementation of 'omics' technologies, and the use of artificial intelligence/self-learning in data analysis. We also briefly discuss how some of the advances can be readily available to the practitioner, through the implementation of 'on-farm' devices and telemedicine.

Are There Differences between Methods Used for the Objective Estimation of Boar Sperm Concentration and Motility?

Artificial insemination in the swine industry, as in other species, demands adequate semen handling and accurate evaluation for the preparation of seminal doses. Sperm concentration and motility estimates are part of the semen evaluation process and are considered important for maximizing the yield of doses for insemination. In this study, methods were examined for their accuracy in the estimation of boar sperm concentration and motility. Assessments of sperm concentration were carried out using iSperm^®, ISAS^® v1, Open CASA v2, and the Accuread^® photometer. Analyses of sperm motility were performed with iSperm^®, ISAS^® v1, and Open CASA v2 systems. In this study, boar semen samples were collected from 10 healthy males from two genetic lines. There were no relevant differences between sire lines when sperm concentration was assessed. A Bayesian analysis was applied to the four methods used to assess sperm concentration to examine whether there are relevant differences between them. Results suggested differences in the four methods, with a probability of relevance (PR) of 0.86-1.00. The iSperm^® method revealed higher concentration values within the highest posterior density region at 95% confidence interval (HPD_95%) = 167.0, 224.2 M/mL, whereas Open CASA v2 showed the lowest values, with HPD_95% = 99.3, 155.9 M/mL. The iSperm^® demonstrated higher reliability in measuring sperm concentration compared to other methods or devices within the given range of confidence. ANOVAs revealed relevant differences in the three methods of motility estimation. Overall, differences in boar sperm concentration and motility estimates were found using various methods, but further studies are needed for better characterization of these differences.

Predicting the Outcome of Equine Artificial Inseminations Using Chilled Semen

This study aimed to determine whether an analysis of stallion ejaculate could accurately predict the likelihood of pregnancy resulting from artificial insemination in mares. This study involved 46 inseminations of 41 mares, using 7 standardbred stallions over a 5-week period at an Australian pacing stud. Semen quality was assessed immediately after collection and again after chilling at ~5 °C for 24 h. The assessment involved evaluating ejaculate volume, sperm concentration, and motility parameters using an iSperm^® Equine portable device. After the initial evaluation, a subpopulation of cells was subjected to a migration assay through a 5 µm polycarbonate filter within a Samson™ isolation chamber over a 15 min period. The cells were assessed for their concentration, motility parameters, and ability to reduce the membrane impermeant tetrazolium salt WST-1. The data, combined with the stallion and mare's ages, were used to predict the likelihood of pregnancy, as confirmed by rectal ultrasound sonography performed 14 days post ovulation. The criteria used to predict pregnancy were optimized for each individual stallion, resulting in an overall accuracy of 87.9% if analyzed pre-chilling and 95% if analyzed post-chilling. This study suggests that an analysis of stallion ejaculate can be used to predict the likelihood of pregnancy resulting from artificial insemination in mares with a high level of accuracy.

Assessment of sperm motility in livestock: Perspectives based on sperm swimming conditions in vivo

Evaluation of sperm motility is well-established in farm animals for quickly selecting ejaculates for semen processing into insemination doses and for evaluating the quality of preserved semen. Likewise, sperm motility is a fundamental parameter used by spermatologists in basic and applied science. Motility is commonly assessed using computer-assisted semen analysis (CASA). Recent increases in computational power, as well as utilization of mobile CASA systems and open-source CASA programs, broaden the possibilities for motility evaluation. Despite this technological progress, the potential of computer-generated motility data to assess male fertility remains challenging and may be limited. Relevance for fertility assessment could be improved if measurement conditions would more closely mimic the in vivo situation. Hence, this review is focused on the current trends of automated semen assessment in livestock and explores perspectives for future use with respect to the physiological and physical conditions encountered by sperm in the female reproductive tract. Validation of current CASA systems with more complex, microfluidic-based devices mimicking the female reproductive tract environment could improve the value of sperm kinematic data for assessing the fertilizing capacity of semen samples, not only for application in livestock but also for use in conducting assisted reproduction techniques in other species.

Slow cooling is beneficial for storage of frozen-thawed equine spermatozoa

Cooled storage of semen after thawing can expand the use of frozen semen, providing the possibility of thawing and evaluating the semen at the storage site and subsequently shipping the semen. Our objectives were (1) to examine the motility and viability of frozen-thawed semen after cooled storage and (2) to compare two cooled-storage protocols for frozen-thawed semen. The samples (n=31) were either placed immediately in a passive cooling box for 8 or 24h (CB) or placed in a refrigerator at 4°C for 30 minutes and then transferred to a passive cooling box (REF). Total and progressive motility were similar at T0 and T8-REF and at T0.5 and T8.5-REF. However, a significant reduction was observed in total motility (-8.12%) between T0 and T8-CB, and in total (-9.96%) and progressive motility (-8.52%) between T0.5 and T8.5-CB (p<0.05). A significant reduction was also observed in total and progressive motility between T0 and T24, and between T0.5 and T24.5 for both storage protocols (CB and REF). Viability was lower in T8.5-CB (-11.87%), in T8.5-REF (-9.65%), in T24.5-CB (-13.52%), and in T24.5-REF (-12.32%) compared to T0.5 (p<0.05). Our results demonstrate that sperm motility and viability decrease during cooled storage. However, storing the samples at 4°C for 30 minutes before placing the semen in a passive cooling box could mitigate the adverse effect of cooling during short-term storage (8hr). Additionally, we observed individual variation between samples indicating that this protocol might not be suitable for all stallions. Our data shows that slow cooling and storage of frozen-thawed semen is a valid alternative that allows the expansion of frozen semen in breeding programs.

Sperm Gone Smart: A Portable Device (iSperm®) to Assess Semen Concentration and Motility in Dogs

The iSperm® is a portable device for semen analysis. This study aimed to investigate its correlation with a conventional computer-assisted sperm analyzer (ISAS®v1) for the assessment of semen concentration and kinematic parameters in dogs (n = 224). The intra-assay variability of both devices and their ability to estimate semen concentration at a fixed value of 40 × 106/mL were also investigated. Results showed that the intra-assay variability was lower for the ISAS®v1 for all parameters compared to the iSperm®. Hence, iSperm® estimates were more variable in-between fields. Both the iSperm® and the ISAS®v1 were not reliable in estimating semen concentration (ISAS®v1: median 30 × 106/mL, interquartile range (IQR) 12, p < 0.01; iSperm®: median 35.12 × 106/mL, IQR 11.11, p < 0.01). Finally, positive correlations were found between both devices with stronger correlations obtained when four fields were analyzed by the iSperm®. However, the low number of spermatozoa analyzed per field and the inability to avoid artifacts are downsides that currently limit the reliability of the iSperm®. Therefore, the software of iSperm® needs some improvement to make it a valid and practical alternative to automated computerized systems for the analysis of canine semen.

Assessment of an iPad-based sperm motility analyzer for determination of canine sperm motility

The objective of this study was to evaluate the repeatability and accuracy of canine sperm motility (total and progressive) assessment with a tablet-based Canine iSperm instrument compared to computer-assisted sperm analysis (CASA). The experiment used fresh and frozen/thawed canine semen samples for comparisons of semen analysis parameters (concentration, total motility, and progressive motility) between a CASA system, iSperm, and NucleoCounter SP-100 (concentration) instruments. Spearman's Rho correlational analysis was used to identify significant associations between motility assessment methods. Significant positive correlations were found between CASA assessment and iSperm for both progressive and total motility measurements. We also determined the coefficient of variation (CV) for repeatability of sample analysis for iSperm and CASA for fresh sperm, wherein each sample was assessed 10 times on both devices. For fresh and frozen-thawed samples, concentration assessment by iSperm showed high variability (CV= 19.9 ± 1.5%). For iSperm assessment of total and progressive motility, the CVs were 6.3 ± 0.5% and 10.7 ± 0.8%, respectively. The results indicate that the iSperm application offers an accurate and alternative measurement of motility to traditional CASA analysis, though caution should be taken when assessing concentration due to the high CV observed in this study.