Thermographic Evaluation of Climatic Conditions on Lambs from Different Genetic Groups

In production systems the characterization of genetic resources in relation to their capacity to respond to environmental conditions is necessary. The objective of this study was to evaluate the use of infrared thermography for separation of animals from different genetic groups and determine which phenotypic traits are important for climatic adaptation. A total of 126 suckling lambs from four different genetic groups (Santa Inês--SI, Bergamasca--B, Bergamasca X Santa Inês--BS, and Ile de France X Santa Inês--IL) were used. The animals were divided into two groups, one housed and another in an outside paddock. Thermograph photographs were taken at four-hour intervals over three full days. Temperatures of the nose, skull, neck, fore and rear flanks and rump were measured, as well as coat depth, the density and length of hairs, reflectance and color. The daily temperature range during the experimental period was more than 20°C, with animals experiencing heat (12 h to 15 h) and cold (24 h to 4 h) stress. The three main phenotypic traits that influenced genetic group separation were hair density, height of coat, and length of hairs. Thermograph temperatures were able to detect different responses of the genetic groups to the environment. Therefore, infrared thermography is a promising technique to evaluate the response of animals to the environment and to differentiate between genetic groups.