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Title: Rooster Semen Cryopreservation: Effect of Pedigree Line and Male Age on Post-Thaw Sperm Function

item Long, Julie
item Bongalhardo, Denise
item PELAEZ, JESUS - Former ARS Employee

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2010
Publication Date: 5/1/2010
Citation: Long, J.A., Bongalhardo, D.C., Pelaez, J., Saxena, S., Settar, P., O'Sullivan, N.P., Fulton, J.E. 2010. Rooster Semen Cryopreservation: Effect of Pedigree Line and Male Age on Post-Thaw Sperm Function. Poultry Science. May: 89(5):966-73

Interpretive Summary: Primary poultry breeders would benefit from the ability to stockpile germplasm from elite lines, especially in the context of disease outbreak; however, fertility rates from frozen/thawed poultry semen are highly variable and unreliable for preservation of genetic stocks. Given the inability of primary breeders to rely on cryopreserved semen for sufficient germplasm archiving, our approach was to determine the freezability of semen from multiple elite layer lines by evaluating the function of frozen/thawed spermatozoa from individual males at two distinct ages, with the goal of developing a model to further delineate the factors responsible for successful cryopreservation. We present here the initial findings that support the feasibility of this model for understanding the compromised physiology of cryopreserved poultry spermatozoa.

Technical Abstract: The fertility rates of cryopreserved poultry semen are highly variable and not reliable for use in preservation of commercial genetic stocks. Our objective was to evaluate the cryosurvival of semen from 8 pedigreed layer lines at the onset and end of production. Semen from 160 roosters (20/line) was frozen individually with 11% glycerol at 6 and 12 mths of age. Glycerol was removed from thawed semen by Accudenz gradient centrifugation. The viability of thawed sperm from each male was determined using SYBR/PI and flow cytometry; sperm velocity parameters were measured using CASA. The fertilizing ability of thawed sperm was evaluated in vitro by assessing hydrolysis of the inner perivitelline membrane. The post-thaw function of sperm from the elite lines varied widely, despite the fact that fresh semen from all of these lines typically yields high fertility rates. The percentage of thawed sperm with intact plasma membranes ranged from 27.8 ± 2.1 to 49.6 ± 1.9 and varied among lines and between age groups. Thawed sperm from 2 lines consistently demonstrated the highest and lowest motility parameters; whereas the velocity parameters of the remaining 6 lines varied widely. The mean number of hydrolysis points per mm2 of inner perivitelline membrane ranged from 12.5 ± 4.1 (Line 2) to 103.3 ± 30.2 (Line 6). Age effects were observed for 4/8 lines, with 1 line consistently showed improved post-thaw sperm function at 12 mths of age for all 3 assays. Three other lines showed improvement for one or two of the sperm function assays, all at 12 mths of age. These results demonstrate variability among pedigreed lines in withstanding glycerol-based semen cryopreservation and provide a model for delineating genotypic and phenotypic factors impacting sperm cryosurvival.