Physical separation and reduction of contact duration with sexually hyperactive bucks decrease testosterone...

Area of Science:

• Animal behavior
• Reproductive endocrinology
• Mammalian physiology

Background:

• The "buck-to-buck effect" describes how sexually hyperactive bucks stimulate testosterone secretion and sexual behavior in hypoactive bucks during seasonal sexual rest.
• Understanding factors influencing this effect is crucial for managing reproductive cycles in livestock.

Purpose of the Study:

• To determine if physical separation or reduced contact duration with sexually hyperactive bucks alters testosterone concentrations and sexual behavior in sexually hypoactive bucks.
• To investigate the impact of modified social proximity on the "buck-to-buck effect".

Main Methods:

• Experiment 1: Sexually hypoactive bucks were either separated by a fence or in permanent contact with sexually hyperactive bucks for 60 days under natural photoperiod.
• Experiment 2: The duration of contact between sexually hypoactive and hyperactive bucks was varied (31 days vs. 10 days).
• Hormonal (testosterone) and behavioral (nudging) parameters were measured in all groups.

Main Results:

• In Experiment 1, bucks in constant contact with hyperactive bucks showed significantly higher testosterone levels and nudging behavior compared to separated bucks.
• In Experiment 2, bucks with longer contact duration (31 days) exhibited higher testosterone levels and nudging behavior than those with shorter contact (10 days) after an initial period.
• Both experiments demonstrated a significant effect of time and an interaction between time and group on the measured parameters.

Conclusions:

• Physical separation and reduced contact duration with sexually hyperactive bucks significantly decrease testosterone concentrations and sexual behavior in hypoactive bucks.
• The "buck-to-buck effect" is modulated by the degree and duration of social interaction between bucks.
• These findings have implications for understanding social influences on reproductive physiology in male mammals.