Using infrared thermography to measure the body surface temperature of crossbred cows and calves in the semi-arid region of Minas Gerais, Brazil

This study aimed to evaluate the body surface temperature of crossbreed cows and calves managed in the semi-arid region of Minas Gerais (Brazil), using the infrared thermography technique. The thermal environment was characterized by daily collections of meteorological variables and subsequent calculation of thermal indices. Body surface temperature (BST) was measured at 6: 00, 12: 00 and 16: 00 hours, at 1.0, 1.5, 2.0 and 4.0 meters distances from the animals to measure the right and left flank temperature and compare with the different information obtained in the literature. The thermal environment was classified as an emergency from 12: 00. There was no significative difference between the distances studied, where the body surface temperature of cows and calves was 36.8 degrees C and 38.2 degrees C, respectively. There was significative interaction between the hours and the laterality of the body, where at 7: 00 the BST was higher in the left flank due to the more intense ruminal activity and at 16: 00 there was no difference in the BST, but in this period the higher BST values were observed due to the thermal environment. It is possible to obtain BST by means of thermographic camera reliably up to a distance of 2.0 m. The thermal environment elevates BST in the afternoon period, but the adaptability of the animals obtained through heterosis does not expose them to the heat stress condition. The microclimate of the shaded environment and in full sun does not interfere with the calves' preference of accommodation.