Assessment of Climatic Effects on Sperm Traits Using Scrotal Infrared Thermography in Bulls

Climatic factors such as high environmental temperature have great influence on animal's reproduction. The use of infrared thermograph as a tool on reproductive failures detection reveals potential in field procedures. Sperm motility (M), mass motion (MM) andvigor (VIG) were evaluated in sperm samples from 17 Bradford bullsaged approximately 24 months at the beginning the study. Infrared thermography images and data were collected using an infrared FLIR T 300 camera and Quick Report1.2 SP2 software to determine the temperature of the proximal and distal poles of the testis andto assess the testicular temperature gradient. The seasonal effects on physiological, seminal and climatic variables were analyzed bythe GLMANOVA and CORR proceduresusing SAS®.The microclimatic factors were recorded in hourly intervals,and the daily mean temperature and mean relative humidity were calculatedto determine the dailytemperature-humidity index (THI)every day for one year. The temperature gradient (TG) variations of the testes were significantly higher in the autumn (4.5oC), winter (4.0oC) andspring (2.9oC) compared to summer (0.9oC) (P < 0.05). Ocular globe temperatures were lower in the winter (27.6oC) and autumn (26.8oC) compared to summer (33.9oC) and spring (31.1oC) (P < 0.05). The average MM (2.58), M (52.64) and VIG (2.70) of the semen decreased in the summer compared to the other seasons (P< 0.01). The TG was negatively correlated with THI (-0.44; P< 0.05). For the seminal variables, MaD (-0.45; P< 0.05) and TD (-0.50; P< 0.01) presented a negative correlation with TG. The TG had a positive correlation between M and VIG, which had values of 0.36 and 0.35, respectively (P< 0.05). We have concluded that infrared thermography can be used to assess the testicular temperature gradient and its consequences on physical and quantitative aspects of sperm.