Since measuring temperature with a contact thermometer is time-consuming, we aimed to find out whether a pig's temperature could be measured equally well or even better with a thermal imaging camera rather than with a rectal thermometer.
The measurements were carried out on five different areas: the eye, the inner ear, the outer ear, the perianal area and the rectum. The aim was to find out which area is the most suitable for measuring the body temperature with a thermal imaging camera, so that the measured temperature will be the closest to the temperature measured in the rectum. Namely, we always used the rectal temperature measured with a calibrated contact thermometer as the reference.
We used the thermal imaging camera Flir T650sc and the thermal imaging camera Fluke TiS45 for measuring the temperature on five areas in the farrowing sow. The Flir T650sc is a high-quality product belonging to a higher price bracket, whereas the Fluke TiS45 is a lower quality camera, and belongs to a lower price bracket. The goal of taking temperature with two thermal imaging cameras was to determine whether it is possible to measure the pig's temperature with an inexpensive thermal imaging camera just as accurately as with a more expensive one. In the pigpen and gestation crate we measured with only one thermal imaging camera because the pigs in the pigpen are in groups and move around freely; and in the gestation crate because of the inaccessibility of the measuring areas; it is namely impossible to measure temperature with both thermal imaging cameras at the same time and get quality results. That is why we used the thermal imaging camera Flir T650sc. The measuring results of the two thermal imaging cameras are different. When comparing the measured rectal temperature with the temperature measurements of the pig's inner ear (auditory canal), it can be seen that the thermal imaging camera Flir T650sc is more accurate than the thermal imagining camera Fluke TiS45. On the other measuring areas where the temperature does not match the reference rectal temperature, the differences were observed between the temperatures measured on the same measuring area, but measured with different thermal imaging cameras.
What became apparent was that the temperature closest to the reference rectal temperature was the temperature of the inner ear (auditory canal), measured with a thermal imaging camera. However, deviations were also present. The deviations occur because of hairiness, heat transfer from other objects onto the pig and the measuring angle.
We realized soon that carrying out measurements would be difficult because pigs are not obedient animals. Especially problematic was the fact that the animal did not keep still long enough to enable us to measure its temperature with a thermal imaging camera on the selected spots. We partly solved this problem by having two individuals carrying out measurements (one person measured, one assisted). There was another problem – namely the heat transfer from other objects, especially the floor of the pig-shed, to the pig. We tried to solve this problem by observing the animal in a standing position for a longer period of time, and then measuring its temperature. Another problem was the hairiness of the skin. Because not all pigs are hairy to the same extent, the temperature changed on each measuring area in relation to the hairiness of the skin.
In the course of data processing and analysis, and after consulting the breeder, we concluded that measuring temperature with a thermal imaging camera is more time consuming, less accurate, and depends on other factors (the hairiness of the skin, heat transfer from other objects, the measuring angle, background temperature, the animal's movement). When considering also the costs of purchasing a thermal imaging camera, the use of it is economically unjustified. Temperature can be taken faster and more accurately with a contact thermometer in the rectum. It turned out that the thermal imaging camera Flir T650sc is better than the Fluke TiS45 because the temperatures of the inner ear (auditory canal) that were measured come closer to the referential temperatures measured in the rectum.