TITLE:
Infrared Thermography and Testicular Morphometry in Rams of Different Breeds: Implications for Reproductive Fitness in Tropical Environments
AUTHORS:
Amanda de Oliveira Pessoa Moniz, Estevam Rodrigues de Souza, Luan Sitó-Silva, Rogério Araújo de Almeida Filho, Rogério Antonio de Oliveira, Luiz Gustavo Ferreira de Lima, Claudio Willian de Oliveira Delfes-Camargo, Eunice Oba
KEYWORDS:
Sheep, Thermography, Testicular Thermoregulation, Heat Stress
JOURNAL NAME:
Journal of Biosciences and Medicines,
Vol.13 No.9,
September
2,
2025
ABSTRACT: The Brazilian sheep industry relies on extensive production systems, where rams are frequently exposed to high ambient temperatures and low relative humidity, potentially compromising reproductive efficiency. Testicular thermoregulation is critical for spermatogenesis, requiring scrotal temperature to be 2˚C-6˚C below core body temperature. This study aimed to evaluate testicular shape and infrared thermography (IRT) in 38 rams from four different breeds (Poll Dorset, Dorper, Santa Inês, and Suffolk) managed under tropical extensive conditions in Botucatu, Brazil. Testicular morphometry (scrotal circumference—SC, width, length, volume) and IRT of scrotal regions (dorsal, medial, ventral), as well as rectal, eye, and nose temperatures, were assessed. Significant differences were found in SC among breeds (P = 0.024), with Dorper rams having larger SC. IRT revealed significant variations in the ventral temperature of the right testicle (P = 0.039), dorsal temperature of the left testicle (P = 0.006), and mean dorsal temperature of both testicles (P = 0.025). Poll Dorset, a wooled breed, exhibited higher mean dorsal testicular temperatures, consistent with wool’s insulating effect hindering heat dissipation. Conversely, Suffolk rams, despite being wooled, showed lower dorsal testicular temperatures, suggesting complex breed-specific thermoregulatory mechanisms or anatomical adaptations. Dorper rams (hair, white-coated) showed lower ventral scrotal temperatures, indicating better heat dissipation. Nose temperature also varied significantly (P