The Relationship Between Sperm Function and Diet: Toms are What They Eat

Introduction 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. As part of a long-term research plan to determine how and why poultry sperm lose functional competence during hypothermic semen storage, several factors have been identified that may help to improve poultry sperm cryopreservation (Long, 2006; Long and Guthrie, 2006; Peláez and Long, 2007; Blanco et al., 2008; Peláez and Long, 2008; Long et al., 2010; Blanco et al., 2011; Peláez et al., 2011; Long and Conn, 2012). This systematic approach to delineate the physiology responsible for poor sperm cryosurvival, and thus provide mechanisms to improve sperm cryopreservation, does not 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, we are investigating an alternative strategy in the form of temporary dietary modification and/or in vitro manipulation of membrane cholesterol that also should be useful for the long-range goals of improving poultry sperm cryopreservation. Specifically, the goals are to: 1) alter the fat source in the diet to improve cryosurvival of turkey sperm by modifying the sperm membrane lipid composition; 2) change the cholesterol:phospholipid (C:P) ratio in the sperm membrane to improve sperm cryosurvival; and 3) determine if the combination of diet modification and in vitro manipulation of cholesterol content has a synergistic effect on sperm cryosuvival.