Prospective approaches to avoid flock fertility problems: predictive assessment of sperm function traits in poultry

This paper discusses why it is important to evaluate males as individuals and how advances made in understanding and measurement of sperm function can be used to improve reproductive efficiency in poultry. Commercial turkey breeding relies on pooling semen from multiple toms. It generally is assumed that sperm in good quality semen from all toms are equally fecund. (Fecund is defined, for males, as an individual whose semen contains a majority of sperm with the potential of producing fertilized eggs, which includes success at all steps in the fertilization process: sperm movement, storage in the hens' sperm storage tubules, binding and penetrating the perivitelline layer, and fertilization.) However, when DNA fingerprinting was used to determine paternity efficiency after pooling ejaculates from seven or more toms, it was found that 18 of 26 males produced very few, or no, offspring. In addition, the traditional measures of poultry semen quality: semen volume, sperm concentration, sperm viability, and subjective motility assessment, were poor predictors of paternity. In recent years, a concentrated effort has been made to develop and evaluate methods that quantify sperm function in poultry. Methods to measure some of these traits are reviewed: sperm motility, sperm storage in the hen, and sperm binding and penetration of the ovum. Data supporting use of these tools for managing flock fertility from the male perspective are explored.