Permanent contact with females increases testosterone and improves fresh semen traits in pampas deer (Ozotoceros bezoarticus) males

Socio-sexual signals can stimulate neuroendocrinal control of reproduction. The aim of this work was to test the hypothesis that permanent and close contact with females stimulates testosterone production and enhances fresh seminal characteristics of pampas deer males. Five adult males (group CF) were established in a paddock in five breeding groups each comprising one stag and between five and ten hinds. Six adult males (group IS) were held in another paddock without any direct contact with females. Fecal testosterone concentrations were determined for each male, weekly, from October to May. Semen was collected by electro-ejaculation and evaluated before and after the addition of diluents [November: Fructose-Tris-Glycine with 20% egg yolk (FTG); April: Andromed]. Males in contact with females from mid-December to February exhibited significantly (P = 0.04) greater concentrations of testosterone than those without. In November, CF males ejaculated semen of significantly (P = 0.03) higher quality, with a significantly (P = 0.02) greater proportion of progressive motile spermatozoa than IS males. After dilution with FTG, semen from the CF males had greater quality (P = 0.04), a greater percentage of motile spermatozoa (P = 0.04), spermatozoa with progressive motility (P = 0.01), and spermatozoa with intact acrosomes (P = 0.03). Semen from CF males also had lower fractions of spermatozoa with damaged acrosomes (P = 0.04). In April, there were no significant differences in semen properties between the two groups. After the addition of extender, semen from CF males had a greater percentage of spermatozoa with damaged acrosomes (P = 0.04). It is concluded that contact with females stimulates reproductive patterns of male pampas deer, resulting in better fresh semen characteristics before rutting and higher testosterone concentrations during the rut.