Assessment of surface temperatures of buffalo bulls (Bubalus bubalis) raised under tropical conditions using infrared thermography

Abstract

This paper aimed to evaluate the surface temperatures of buffalo bulls using infrared thermography, considering four distinct anatomical parts over time, and to correlate surface temperatures and thermal comfort indexes. The humid tropical climate (Köppen's Afi) was predominant in the research station where the experiment was performed and the trial lasted from April to August. Ten bulls (n=10) were evaluated every 25 days (morning: 6:00-9:00; afternoon: 12:00-15:00) and the parameters assessed were respiratory rate (RR), rectal temperature (RT), and the thermograms of surface temperature for orbital area (ORB), right flank (RF), left flank (LF) and scrotum (SCR). Climatological data was continuously monitored and the Temperature and Humidity Index (THI) and the Index of Comfort of Benezra (ICB) were calculated. The average values of THI were ≥78, and significant differences between shifts were observed (P<0.05). The ICB ranged from 1.96 to 2.25 and significant differences were observed for shifts and throughout the months (P<0.05). The averages of surface temperatures were RT=38.2±0.5°C, ORB=36.1±0.8°C, LF=33.5±2.5°C, RF=35.4±1.7°C and SCR=33.3±1.1°C, which exhibited significant differences for shifts and throughout the months (P<0.05). Positive correlations were obtained between THI and ORB (0.72), RF (0.77), LF (0.75) and SCR (0.41) (P<0.0001). The maximum temperature of ORB showed the highest correlation with RT (0.58, P<0.0001). Therefore, the surface temperatures are subject to climatic variations and increase throughout the day, due to the variation in thermal comfort indexes, and the maximum ORB temperature was the parameter most related to rectal temperature. Lastly, the results indicate that IRT may be a useful non-invasive and accurate tool to detect the variations in ORB, LF, RF and SCR temperature in buffalo bulls.