Non-Invasive Biomarkers in Saliva and Eye Infrared Thermography to Assess the Stress Response of Calves during Transport

Abstract

Animal transport is currently a stressful procedure. Therefore, animal-based indicators are needed for reliable and non-invasive welfare assessment. Saliva is a biospecimen with potential validity for the determination of cortisol and oxidative stress, although its use to assess calf welfare during transport has never been tested. Similarly, the applicability and reliability of infrared thermography to assess temperature change during calves’ transport have never been evaluated. These objectives were outlined following the known and growing need to identify non-invasive methodologies for stress assessment in bovines. This study was conducted on 20 calves of the Arouquesa autochthone breed, at about nine months of age, during their transport to slaughter. For each animal, saliva samples and thermographic images of the eye were collected at three time points: before transport, after transport, and at slaughter. The saliva was then processed to measure cortisol levels and oxidative stress parameters (reactive oxygen species, thiobarbituric acid reactive substance, carbonyls, and advanced oxidation protein products), and the images were analyzed using FLIR Tools+ software. There was an increase in cortisol concentration and oxidative stress parameters (reactive oxygen species, thiobarbituric acid reactive substance, carbonyls, and advanced oxidation protein products) in saliva after transport. An increase in eye temperature triggered by transport was also observed. The cortisol and eye temperature results at slaughter were returned to values similar to those before transport; however, the values of oxidative stress remained increased (mainly TBARS values). These non-invasive techniques seem to be reliable indicators of stress in bovine transport, and oxidative stress parameters in saliva may be a persistent marker for welfare assessment.

Thermal Balance in Male Water Buffaloes Transported by Long and Short Journeys

“…For LJs, the buffaloes might be able to habituate to transport and its related stressors based on what has been indicated in previous studies [37,38]. This coincides with what was observed by Lei et al [39], where they found that 15 to 17 h transport of 20 Arouquesa calves had an initial increase of 3 • C in periocular temperature and a subsequent decrease of 2 • C. The authors concluded that the animals habituated to the transport, although the increase in temperature represents an important metabolic cost, which can be difficult to maintain over a long period as represented by the LJ group. According to the findings of the present study and already published studies, the proposed hypothesis can be rejected.…”

“…This greater variation was also present in the rest of the thermal windows of the facial region for this group. The changes in the temperature of the facial region may be related to parasympathetic activity, the vasodilation response, which generates a lowers cardiac output and blood pressure and the consequent increase in temperature [39]. In particular, the wide distribution of capillaries and arteriovenous anastomoses in these thermal windows facilitates the exchange of body heat with the environment [57].…”

Events with Different Emotional Valence Affect the Eye’s Lacrimal Caruncle Temperature Changes in Sheep

“…Previous studies have provided evidence indicating that the temperature of the lacrimal caruncle in sheep is elevated during short stressful events such as restraint [ 19 ] and shearing [ 45 ]. Furthermore, several studies have also demonstrated that castration [ 46 ], transport [ 47 ], and forced lateralization test in cattle [ 48 ], trimming [ 49 ] and noseband tightening [ 50 ] in horses, and veterinary visits in dogs [ 33 ] resulted in elevations in ocular temperature. The higher temperature of the eye caruncle herein found could be related to ocular vasodilatation causing the greater heat dissipation identified here by the thermographic measurements.…”

Current Knowledge on the Transportation by Road of Cattle, including Unweaned Calves

“…It is also possible to detect changes in the temperature of the skin and extremities using infrared thermography (IRT) as the temperature of those regions is dependent on peripheral blood flow [169,170]. This technique, for example, has enabled the non-invasive analysis of ocular surface temperatures as well as those of other body parts when assessing transport stress in calves [171] and buffaloes [172]. The precise determination of external body surfaces using IRT depends on the effective minimisation of factors, such as skin and hair colour, the emissive properties of the skin, sudden movements, health status, the time of feeding, and external factors, including ambient temperature, relative humidity, sunlight, wind speed, distance between camera lens and the measuring object, and angle of camera [173].…”