Project Number: 8042-31000-105-04-I
Project Type: Interagency Reimbursable Agreement
Start Date: Oct 1, 2013
End Date: Sep 30, 2016
It is well known that cryopreserved semen could be used to regenerate commercial or research poultry lines; however, fertility rates from poultry semen frozen with current methods are not reliable enough for germ-line retrieval, especially from lines with low reproductive efficiency. A long-term research plan to determine how and why poultry spermatozoa lose functional competence during hypothermic semen storage is focused on characterizing the biochemical and cellular changes occurring during the cryogenic process. To date, several factors have been identified that may help to improve poultry sperm cryopreservation. Although this systematic approach will delineate the physiology responsible for poor sperm cryosurvival, and thus provide mechanisms to improve sperm cryopreservation, it cannot address the immediate need for preservation of germplasm from poultry stocks that are currently “at-risk”. To provide a short-term solution for preservation of semen from “at-risk” poultry lines, an alternative strategy in the form of temporary dietary modification and/or in vitro manipulation of membrane cholesterol will be evaluated and is in concert with the long-range goals of improving poultry sperm cryopreservation. This is based on the hypothesis that: 1) altering the fat source in the diet will improve cryosurvival of poultry spermatozoa by modifying the sperm membrane lipid composition; 2) changing the cholesterol:phospholipid ratio in the sperm membrane will improve sperm cryosurvival; and 3) diet modification and in vitro manipulation of the sperm lipid content will have an additive effect on sperm cryosurvival.
The goal of improving poultry sperm cryopreservation through lipid manipulation will be addressed by the following Specific Aims (SA): SA 1. Characterize the lipid and cholesterol profile of spermatozoa before and after cryopreservation from chicken and turkey lines with known (good or poor) cryosurvival. SA 2. Evaluate the efficiency of diets enriched with n-3 or n-6 PUFAs to modify the lipid composition of chicken and turkey sperm membranes and improve sperm cryosurvival. SA 3. Determine the ability of cyclodextrins to alter the C:P ratio in chicken and turkey sperm membranes and improve sperm cryosurvival. SA 4. Test for a synergistic effect of diet and in vitro manipulation of sperm membranes on poultry sperm cryosurvival. All of the pre-freeze sperm quality/function analyses and semen cryopreservation activities for Years 1 and 2 will be conducted at Ohio State University, where the males from the 4 turkey and 3 chicken lines will be maintained. All of the lipid and cholesterol analyses for Years 1 and 2 will be conducted at Colorado State University. All of the post-thaw sperm quality/function analyses and fertility trials for Years 1 and 2 will be conducted at the Beltsville Agricultural Research Center.