Validation of Anatomical Sites for the Measurement of Infrared Body Surface Temperature Variation in Response to Handling and Transport

Abstract

This study aimed at validating the anatomical sites for the measurement of infrared (IR) body surface temperature as a tool to monitor the pigs’ response to handling and transport stress. The selected anatomical sites were the neck (infrared neck temperature—IRNT), rump (infrared rump temperature—IRRT), orbital (infrared orbital temperature—IROT) and behind ears (infrared behind ears temperature—IRBET) regions. A total of 120 pigs were handled from the finishing pen to the loading dock through a handling test course. Two handling types (gentle vs. rough) and number of laps (1 vs. 3) were applied according to a 2 × 2 factorial design. After loading, pigs were transported for 40 min and returned to their home pens. Animal behavior, heart rate, rectal temperature and salivary cortisol concentration were measured for validation. Increased IR body temperature, heart rate and salivary cortisol levels were observed in response to rough handling and longer distance walk (P < 0.05 for all). The greatest correlations were found between IROT and IRBET temperatures and salivary cortisol concentration at the end of the handling test (r = 0.49 and r = 0.50, respectively; P < 0.001 for both). Therefore, IR pig’s head surface temperature may be useful for a comprehensive assessment of the physiological response to handling and transport stress.

Phase Space Analysis of Pig Ear Skin Temperature during Air and Road Transport

“…Lewis [9] reported a wider variability with the average EST of piglets during road transport, ranging from 36.2 °C in summer to 23.1 °C in winter. Although we have not found studies that measure the EST in adult pigs continuously during road transport, Rocha et al [28] report average skin temperatures of 30.89 °C-36.02 °C, measured using thermography, which is similar to our results. The relationship between the surface temperature determined by thermography and the skin temperature determined by probes in contact with the animal has been reported before [29], in which the emissivity is calculated based on the assumption that both temperature measurements are similar.…”

Physiological responses of pigs to preslaughter handling: infrared and thermal imaging applications

“…In that same study, Rocha et al [106], found an increased heart rate during loading in the pigs that received rough handling, and that the pigs subjected to the long walk showed higher saliva cortisol concentrations caused by the physical and emotional stress due to the long distance and high speed of the walk.…”

“…However, Rocha et al [106] validated this method as an indicator of stress by assessing variations in surface temperature at one of two anatomical locations -the back or rump [105,107,108] -or at multiple anatomical sites [40,103]. To this end, Rocha et al [106] measured the temperature responses of 120 pigs on the neck, rump, orbital region and area behind the ears under two conditions: gentle handling-induced stress without exposure to stressors versus rough handling that included abrupt movements, loud noises and/ or physical contact with the personnel. In addition, they evaluated short (30 min) vs. long (90 min) distances walked by pigs and the time travelled (40 min at a loading density of 0.46 m 2 /pig) in a single-deck trailer.…”

“…Other approaches have taken body temperature as a reliable measure of the physiological state of pigs under stressful conditions, such as birthing, when postnatal hypothermia may occur [104], or the stages prior to slaughter [105]. However, Rocha et al [106] validated this method as an indicator of stress by assessing variations in surface temperature at one of two anatomical locations -the back or rump [105,107,108] -or at multiple anatomical sites [40,103]. To this end, Rocha et al [106] measured the temperature responses of 120 pigs on the neck, rump, orbital region and area behind the ears under two conditions: gentle handling-induced stress without exposure to stressors versus rough handling that included abrupt movements, loud noises and/ or physical contact with the personnel.…”

“…Thus, they argue that these regions dissipate heat quickly through blood flow in the head [113], adding that these zones have lower hair density and a thin layer of fat, so they are closer to both the skin and the bloodstream [114]. Based on these findings, it has been possible to establish the ocular orbit and the area behind the ears as valid sites for performing thermographic evaluations associated with the stress responses that pigs present during handling and transport [106]. However, the low correlation between the temperature obtained from the thermograms and rectal temperature, and the absence of any correlation with the measurements of behavioural indicators also led Rocha et al [106] recommended that IR be used with other stress indicators to provide a tool for real-time evaluations of the physiological condition of pigs during handling and transport.…”