Physical separation and reduction of contact duration with sexually hyperactive bucks decrease testosterone concentrations and sexual behaviour in bucks in sexual rest

• Published in: Animal (Cambridge, England) Vol. 18; no. 6; p. 101179
• Main Authors: López-Magaña, N., Tejada, L.M., López-Magaña, D., Hernández, H., Flores, M.J., Vielma, J., Abecia, J.A., Keller, M., Chemineau, P., Delgadillo, J.A.
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 01.06.2024; Published by Elsevier (since 2021) / Cambridge University Press (until 2020); Elsevier
• Subjects: Libido; Life Sciences; Male goats; Photoperiodic treatments; Reproductive seasonality; Sociosexual interactions; Photoperiodic treatments; Reproductive seasonality; Libido; Sociosexual interactions; Male goats; Libido Male goats Photoperiodic treatments Reproductive seasonality Sociosexual interactions
• ISSN: 1751-7311; 1751-732X; 1751-732X
• DOI: 10.1016/j.animal.2024.101179

•Sexually hyperactive bucks stimulate testosterone in males in sexual rest.•Sexually hyperactive bucks also stimulate sexual behaviour in males in sexual rest.•Stimulation occurs in permanent contact with sexually hyperactive bucks.•Separation from hyperactive bucks decreases testosterone and sexual behaviour.•Reduced duration of contact with hyperactive bucks decreases both variables. Sexually hyperactive bucks are more efficient than sexually hypoactive bucks in stimulating testosterone secretion and sexual behaviour in other bucks in seasonal sexual rest by the phenomenon that we called the “buck-to-buck effect”. Here, we determined whether physical separation and reduction of the duration of contact with the sexually hyperactive bucks would modify those parameters in sexually hypoactive bucks exposed to the “buck-to-buck effect”. Bucks were subjected to natural day length throughout the study; this was the sexually hypoactive group. Other bucks were subjected to artificial long days (16 h of light per day) from 15 November to 15 January followed by exposure to natural day length to stimulate their sexual activity during the rest season; this was the sexually hyperactive group. In Experiment 1, we determined testosterone concentrations and sexual behaviour of six sexually hypoactive bucks separated 1.5 m from six sexually hyperactive bucks for 60 days by a metal open work fence, while a control group of six sexually hypoactive bucks was in permanent contact with six sexually hyperactive bucks. In Experiment 2, the duration of contact with sexually hyperactive males was reduced from 31 days (contact group, six bucks) to 10 days (withdraw group, seven bucks). In experiments 1 and 2, there was an effect of time (P < 0.01) and an interaction between time and groups (P < 0.05). In Experiment 1, testosterone plasma concentrations were greater in bucks in contact with sexually hyperactive bucks than in those separated from bucks at 20 and 30 days after the introduction of sexually hyperactive bucks (P < 0.01). The bucks from the contact group also displayed more nudging than bucks from the separated group from 0 to 30 days (P < 0.001). In Experiment 2, testosterone concentrations were greater in the contact group than in those from the withdraw group from 19 to 31 days after the introduction of sexually hyperactive bucks (P < 0.05). Bucks from the withdraw group displayed more nudging than the contact group 7 days after the introduction of the sexually hyperactive bucks (P < 0.05). Afterwards, bucks from the contact group displayed more nudging than the withdraw group 14, 21 and 28 days after the introduction of the sexually hyperactive bucks. We concluded that physical separation and reduction of the duration of contact with the sexually hyperactive bucks decrease testosterone concentrations and sexual behaviour of bucks in sexual rest exposed to the “buck-to-buck effect”.