The effect of adjusting settings within a Computer-Assisted Sperm Analysis (CASA) system on bovine sperm motility and morphology results

Abstract

Semen motility is the most widely recognized semen quality parameter used by Artificial Insemination (AI) centers. With the increasing worldwide export of semen between AI centers there is an increasing need for standardized motility assessment methods. Computer-Assisted Sperm Analysis (CASA) technology is thought to provide an objective motility evaluation; however, results can still vary between laboratories. The aim of present study was to verify the impact of different setting values of the CASA IVOS II on motility, concentration, and morphology of bovine semen samples frozen in an extender with or without egg yolk and then decide on optimal settings for a further validation step across AI centers. Semen straws from 30 different bulls were analyzed using IVOS II with twelve modified settings. No significant changes were observed in semen concentration, percentage of motile sperm or kinetic results for either extender type. However, increasing settings for both STR and VAP progressive (%) from Low, Medium, and High cut-off values significantly (p<0.05) reduced the percentage of detected progressive spermatozoa, in egg yolk extender from 49.5±15.2, 37.2±11.9 to 11.9±5.3%, and in clear extender from 51.9±9.1, 35.8±7.3 to 10.0±2.4%, respectively. In clear extender only, the modification of droplet proximal head length significantly affected the detection of normal sperm percentages (88.0± 4.7 to 95.0±0.6 and 96.0±0.6%) and of the percentage of detected proximal droplets (12.2±4.7, 2.5±2.7 to 0.6±0.2%) for Low, Medium and High values respectively (p<0.05). The identification of sensitivity within the CASA system to changes in set parameters then led to the determination of an optimal IVOS II setting. The existing variability among centers for these phenotypes was reduced when the standardized settings were applied across different CASA units. The results clearly show the importance of applied settings for the final CASA results and emphasize the need for standardized settings to obtain comparable data.

Effects of hyaluronic acid on sperm parameters, mitochondrial function and apoptosis of spermatozoa in Simmental bulls with good and poor freezing ability

“…Sperm were defined as nonmotile if the average path velocity (VAP) and straight‐line velocity (VSL) were less than 30 and 2 µm/s respectively. Sperm were considered progressively motile if VAP > 50 μm/s and straightness index (STR > 70%) (O'meara et al, 2022). An aliquot (5 μL) of frozen‐thawed semen was placed on a counting chamber (depth 20 µm; Leja, Nieuw‐Vennep).…”

525. Detailed analysis of mortality rates in the female progeny of Holstein bulls allows the discovery of new dominant genetic defects

“…for a cohort of 50 bulls, including Mo, that had their semen collected on a routine basis in the same artificial insemination center: the mean volume of the ejaculate (in mL measured by weighting), its concentration (in million spermatozoids per milliliter, measured by spectrophotometry), fresh mass motility and individual motility (in score and percentage, respectively, based on microscope observation), as well as post-freezing mean motility and progressive motility, measured with computer-assisted sperm analysis and IVOS II (O'Meara et al, 2022). The number of records per bull and trait ranged from 2 to 39.…”