Influence of circulating testosterone concentration on sperm cryoresistance: The ibex as an experimental model

Background Recent studies have noted that the circulating testosterone concentration may affect the ability of spermatozoa to survive cryopreservation. However, few attempts to confirm such a relationship have been made. Wild ruminant species have very marked seasonal changes in their reproductive function and strong annual changes in their plasma testosterone concentration. Objectives The present work examines the influence of induced changes in testosterone secretion on sperm variables following conventional slow freezing and ultra‐rapid freezing, using the Iberian ibex as an experimental model. Materials and Methods In a first experiment, testosterone levels were reduced in the middle of the rutting season (December) using the antiandrogen cyproterone acetate (CA). In a second experiment, testosterone levels were increased at the end of the rutting season (January) via the use of the androgen testosterone propionate (TP). Results During December, the testosterone concentration was found to be higher in the blood and seminal plasma of untreated males than in those of CA‐treated males (p