Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 8, 2005
Publication Date: February 6, 2006
Citation: Long, J.A. 2006. Avian semen cryopreservation: what are the biological challenges? Poultry Science. 85:232-236.
Interpretive Summary: The existence of quantitative differences between species and even among lines/strains is an important determinant of the fertility of cryopreserved semen, and necessitates that the development of successful freezing procedures involve more than the identification or application of novel cryoprotectants and additives. It is evident that successful cryopreservation methods for turkey and chicken sperm will require different strategies. This rationale also can be extended for the many unique poultry research stocks that need to be preserved, as the tolerance of poultry sperm to cryopreservation varies among genotypic strains of chickens. Elucidation of compromised poultry sperm function after cryopreservation, including structural changes in the plasma membrane and energy production by the mitochondria, is being investigated using pedigreed pure lines and congenic research lines.
More than fifty years ago, the discovery of glycerol’s cryoprotective properties pioneered the success of modern cryobiology and led to the development of semen cryopreservation for a wide range of species. Despite the fact that this scientific breakthrough was accomplished with rooster semen, the overall fertility rates with frozen/thawed poultry semen are highly variable and not reliable enough for use in commercial production or preservation of genetic stocks. Moreover, significant differences exist among the commercial poultry species (turkey, broiler-type chicken and layer-type chicken) in terms of the viability and functionality of sperm after cryopreservation. In particular, the fertility rates from frozen/thawed turkey semen consistently have been lower than cryopreserved chicken semen. Several comprehensive reviews have been published summarizing the empirical studies involving cryoprotectant type and packaging method, as well as freezing and thawing rates, for avian sperm cryopreservation. The purpose of this invited paper is to highlight the biological challenges associated with avian semen cryopreservation and to suggest novel approaches for investigating the viability of frozen/thawed poultry semen.