Estimation of Rectal Temperature of Goats Based on Surface Temperature

Abstract

Infrared thermography (IR) is a non-invasive tool with potential to indicate changes in the animal's thermal conditions in response to the thermally stressful environment. The objective of this study was to evaluate the application of IR to estimate the rectal temperature of crossbred goats of the Boer breed. Six male crossbred goats of the Boer breed were distributed in a completely randomized design and submitted to temperatures of 26, 30 and 34 °C. Rectal temperature (RT) and thermograms data were collected from animals at each air temperature evaluated. In the thermograms, the temperatures of the ocular globe (PT), head (HT), shoulder (ST), hindquarter (HQ) and maximum infrared (IRMax) of the animals' surfaces were collected, the latter being observed in the lower region of the animals' eyes, at all air temperatures evaluated. The correlation of PT, HT, ST, HQ and IRMax data with the RT was evaluated through the Pearson coefficient analysis and the concordance using Bland-Altman diagrams. With the exception of the IRMax surface temperature, the others were adequate for the accurate estimation of RT, with PT standing out for presenting the highest correlation coefficient with RT (r = 0.951) and estimation errors varying in the range of ± 0.27 °C.

Utilization of Infrared Thermography in Assessing Thermal Responses of Farm Animals under Heat Stress

“…Due to this, IRT can detect these vasomotor changes [96,97]. A study carried out by Marques et al [14] evaluated the potential of IRT as a tool to assess thermal changes in six male Boer crossbred goats exposed to three different temperatures of 26, 30, and 34 • C. By assessing the surface temperature of the ocular region, head, shoulder, and hindlimbs, the authors observed that the surface temperature of all regions significantly increased by 2 • C after exposure to the highest temperature. Moreover, it was also observed that the ocular temperature was positively correlated with the rectal temperature of the animals (r = 0.95).…”

“…However, it is essential to establish which thermal window could be more suitable to show sympathetic activity after HS [99,100]. One of the most used thermal windows to find associations with rectal temperature is the ocular region [14,15,98]. This anatomical region, in particular, the lacrimal caruncle blood supply from the infraorbital artery, is a region highly sensible to vasomotor changes [9].…”

“…Our previous studies have shown that IRT has benefits over the gold standard of rectal temperature (RT) since it is a noninvasive tool that evaluates peripheral vasomotor changes closely related to body core temperature when the animal is in a thermal neutral state and nondiseased [13]. Several studies have reported that increases in surface temperature can be related to increases in core temperature due to vasodilation of dermal blood vessels [14,15]. For example, zones with rich arteriovenous anastomoses, glabrous skin, or sparse hair are called "thermal windows" because these areas promote and facilitate heat exchange through vasomotor modulation [16], providing an approximation of body core temperature [17].…”

Mason et al Preprint_Goat Emotions, Cognition and Personality

“…an experimenter guiding animals loudly with exaggerated arm movements to a nearby pen (Bartolomé et al 2019). As eye temperature correlates strongly with core temperature in goats (Marques et al 2021), we may expect eye and core temperature to increase in tandem with decreases in temperature of other regions, such as the muzzle (e.g. Proctor and Carder 2016).…”

“…However, the use of this technology also suffers from several disadvantages that must be carefully considered before it can be effectively applied in practice. For example, skin temperature is affected by numerous endogenous factors, such as individual, breed, sex and physical activity (also affects cardiac measures; Jansson et al 2021, Travain andValsecchi 2021), as well as environmental variables, such as ambient temperature, humidity and wind intensity, which influence peripheral temperatures both directly and through homeostatic processes (Marques et al 2021, Jansson et al 2021. Further extraneous variables that influence the accuracy of peripheral temperature readings include distance or angle of the subject to the camera (Tattersall 2016, Ijichi et al 2020, the ROI chosen, its size and the specific measure used (i.e.…”