No abstract

Single Layer Centrifugation (SLC) of spermatozoa through a species-specific colloid has been shown to be effective in selecting the best spermatozoa from stallion semen. The method is easier to use and less time-consuming than density gradient centrifugation (DGC), and has been scaled-up to allow whole ejaculates to be processed in a practical manner. The major applications for SLC-sperm selection are as follows: to improve sperm quality in artificial insemination (AI) doses, particularly for "problem" stallions; to increase the "shelf-life" of normal sperm samples, either by processing the fresh semen before preparing AI doses, or by processing the stored semen dose to extract the best spermatozoa; to circumvent the problem of spermatozoa that do not tolerate cooling to 4-6°C; to improve cryosurvival by removing dead and dying spermatozoa prior to cryopreservation, or selecting the live spermatozoa post-thawing; to select morphologically normal spermatozoa with intact chromatin from sub-fertile stallion semen for ICSI, thus increasing the number of blastocysts; to remove pathogens (viruses, bacteria); to accelerate the process of flow cytometric sex selection by removing the dead and dying sperm before passage through the laser beam; to conserve rare breeds. These applications are discussed and practical examples provided.