Subjective semen evaluation using standard optical microscopy is the most common practice. Semen parameters routinely assessed are volume, concentration, progressive motility, and morphology. However, computer-aided sperm analysis (CASA) represents an objective evaluation, sperm assessment that are reproducible and reliable. Such semen parameters have not been evaluated in Afrikaner, Brahman, and Bonsmara bulls’ semen. The present study evaluated the sperm motion and kinematics characteristics of semen from stud Afrikaner, Brahman, Bonsmara, and Nguni bulls using CASA technology. The electro-ejaculator was used for semen collection from Afrikaner (n = 11), Brahman (n = 7), Bonsmara (n = 10) and Nguni (n = 16) bulls of known and proven fertility. Semen was collected following 4 days of resting period. The bulls ranged between 5 and 6 years of age. After collection, the semen samples were immediately transferred to a thermo-flask and maintained at 37°C for further evaluation in the mobile laboratory (Nedambale, 2014). The CASA-Sperm Class Analyzer® system (Microptic, Barcelona, Spain) was used to evaluate sperm motion, velocity, and kinematic parameters or characteristics of raw/fresh semen from 4 cattle breeds. Data were analysed using GenStat® statistical programme (VSN International, Hemel Hempstead, United Kingdom). Treatment means were compared using one-way ANOVA. The total sperm motility rate was similar for all breeds: Afrikaner (92.2 ± 4.2), Brahman (90.7 ± 9.0), Bonsmara (93.9 ± 4.0), and Nguni (96.0 ± 2.7). However, Brahman and Afrikaner bull semen had higher sperm cells moving in a progressive motility of 57.3 and 45.6%, respectively, compared with other breeds (P < 0.05). Nguni, Afrikaner, and Bonsmara had the highest sperm cells moving in a rapid movement of 73.7, 72.4, and 67.4% (P > 0.05), respectively. The bulls sperm trajectories had a variation, as they were recorded to be irregular and not linear (P < 0.05). The straight-line sperm velocity (µm s−1), wobbling %, and amplitude of lateral head displacement % was similar for the 4 breeds (P > 0.05). In conclusion, CASA technology was a useful technique for assessing differences in sperm motion and kinematic (motility and velocity characteristics) among different bull breeds.
CASA: tracking the past and plotting the future
