Proceeding of the Biennial Conference of the Association for Applied Animal Andrology

Semen evaluation via traditional light microscopy provides useful information about sperm motility and morphology, yet it has a limited utility in predicting reproductive performance due to its subjective nature and inconsistency among technicians and laboratories. Furthermore, not all sperm abnormalities are detectable with standard light microscopy. As a result, flow cytometric evaluation using biomarkers to detect specific spermatozoon characteristics is growing in popularity in both andrology laboratories and agricultural studs. Fluorescentlylabeled biomarkers can be used to assess a variety of structural and functional properties, including sperm chromatin integrity, acrosomal status, mitochondrial membrane potential, and viability. A variety of vital stains, DNA and mitochondrial dyes, and lectins are best used as fluorescent conjugates in conjunction with sperm flow cytometry. Antibodies are used to detect and quantify proteins that are upor down-regulated in defective sperm. Biomarkers, uniquely found in defective sperm are indicative of poor semen quality and decreased fertility after breeding. Thus, such biomarkers are described as “negative” biomarkers of fertility. Inversely, defective sperm may lack proteins associated with normal sperm structure and function. In conjunction with the availability of sperm-specific probes and biomarkers, the use of new instrumentation is being implemented to disseminate flow cytometry-based semen analysis among andrologists. The advent of sperm quality biomarkers and the implementation of flow cytometry are expected to benefit the cattle industry through cost reduction of sire evaluation and increase of reproductive performance with artificial insemination.