CHOICE OF OPERATING-CONDITIONS TO MINIMIZE SPERM SUBPOPULATION SAMPLING BIAS IN THE ASSESSMENT OF BOAR SEMEN BY COMPUTER-ASSISTED SEMEN ANALYSIS

The performance of a computer-assisted semen analysis system was evalu ated for use with washed boar spermatozoa. Accuracy was tested using a computer graphics-generated series of spots moving along horizontal, vertical, and diagonal paths, with both straight and sinusoidal trajec tories. Observed and expected values agreed to better than +/-5%, and there was exact agreement in many cases. Reproducibility was tested by making 10 measurements of a single prerecorded sequence of boar sperm atozoa. Coefficients of variation were <3% for all sperm motion parame ters tested. Setup conditions affecting the sample statistics of sperm populations were examined. Search radius (10 settings) and minimum tr ack point (10 settings) were varied factorially to evaluate their bias ing effects upon population sampling and accuracy. Low search radius ( <12 mu m) or high minimum track point values (>26 frames) precluded me asurements of rapidly moving cells and thus led to selection of slow-m oving cells. High search radius (>16 mu m) and low minimum track point settings (<22 frames) led to erroneous tracking and poor data quality . Suitable settings for these setup parameters (search radius = 13 mu m; minimum track points = 24) were chosen for use in subsequent fertil ity trials because they caused the least sampling bias.