The use of infrared thermography for welfare assessment during the application of ear tags to lambs

Abstract. The aim of this study was to determine the effect of metal-tipped, plastic-tipped, and electronic ear tags on the likelihood of infection using infrared thermography and to evaluate the effect on welfare by examining the behavioral responses of the lambs. Ninety lambs with an average age of 6 months were used in this study. Before the application of the ear tags, infrared images of the right and left ears of the lambs were taken with the thermal camera and the infrared temperatures were recorded. Measurements were repeated on days 1, 4, 10, and 30 after the ear tag application. The mean of infrared ear temperatures on days 0, 1, 4, 10, and 30 were found to be 14.60, 23.20, 23.77, 20.36, and 17.61 °C for the metal-tipped ear tag group; 15.69, 21.50, 20.42, 18.00, and 16.39 °C for the plastic-tipped ear tag group; and 15.17, 29.47, 27.49, 25.93, and 20.61 °C for the electronic ear tag group. The infrared temperatures on days 1, 4, and 10 in the control and experimental groups were significantly different from each other (P < 0.001). The plastic-tipped ear tags caused fewer problems and are preferred to the traditional ear tags with metal tips. The electronic ear tags caused more inflammatory reactions compared to metal- or plastic-tipped ear tags. The infrared thermography method may be used as a useful tool in the early detection of the inflammatory reactions and infections caused by the application of ear tags.