Ejaculation increases scrotal surface temperature in bulls with intact epididymides.

Area of Science:

• Veterinary Medicine
• Reproductive Physiology
• Animal Science

Background:

• Scrotal surface temperature (SST) is crucial for thermoregulation and male fertility.
• Infrared thermography is a non-invasive tool for assessing SST.
• Understanding ejaculation's impact on SST is vital for accurate fertility evaluations.

Purpose of the Study:

• To investigate the effects of ejaculation on scrotal surface temperature (SST) in bulls using infrared thermography.
• To determine if the cauda epididymides play a role in the ejaculation-induced SST increase.

Main Methods:

• Infrared thermography was used to measure SST in Holstein, Angus, and Simmental cross bulls before and after ejaculation.
• Ejaculation was induced via artificial vagina (spontaneous) or electroejaculation.
• A subset of Simmental cross bulls underwent caudal epididymectomy before electroejaculation.

Main Results:

• Spontaneous ejaculation and electroejaculation significantly increased SST, especially at the bottom of the scrotum.
• Electroejaculation led to significant increases in top, bottom, and average SST in Simmental cross bulls.
• No significant SST increase was observed after electroejaculation in bulls with caudal epididectomies.

Conclusions:

• Ejaculation, both spontaneous and electroejaculated, elevates scrotal surface temperature in bulls.
• The cauda epididymides appear to mediate the increase in SST following ejaculation.
• Infrared thermography for scrotal thermoregulation should be conducted before semen collection to avoid misleading results.