ABSTRACT This study evaluates the dynamics of heat zones in the load and its relationship with the stress of pigs during transport. Four journeys of 170 km were monitored, recording the physiological variables of 192 animals (48 per journey), namely rectal temperature (RT), body temperature (BT), respiratory rate (RR), blood lactate concentrations and salivary cortisol. Heat zones and ventilation patterns were characterized by the spatial variability of the enthalpy and the Computational Fluid Dynamics of the load. The formation of a thermal core was observed in the frontal region of the load, which extended through the lower (LD) and upper (UD) decks. Pigs transported in the LD had higher means of RR (UD = 89 and LD = 94 breaths/min), and salivary cortisol (UD = 33.84 and LD = 34.92 ng/mL). The pigs transported in the UD presented the highest mean BT (UD = 38.9 and LD = 38.1 °C) and lactate (UD = 61.63 and LD = 58.26 mg/dL). Pigs transported in the LD of the load were more susceptible to thermal stress, while pigs transported in the UD showed greater physical stress and muscle exhaustion.

ABSTRACT The objective of this study was to evaluate the reactivity of the pupillary area (PA) as a non-invasive method for diagnosing stress in piglets submitted to transport. A total of 10 journeys were monitored and grouped according to the transport distance (15 and 75 km). Were sampled 360 piglets (25±3.8 kg) to measure the PA, body temperature (BT), and serum concentrations of cortisol and creatine kinase (CK). The micrometeorological characterization of the load was performed using enthalpy comfort index (ECI). It was possible to identify an increase of 19.32% (+18.91 mm2; P< 0.001) in PA of piglets transported in shorter journeys (15 km), as well as the highest mean values of BT (+ 1.24 °C; P< 0.001), cortisol (+ 2.37 ng/mL; P< 0.001) and CK (+ 379 U/L; P= 0.025). In this study, high correlations of PA were observed with r = 0.922, 0.900, 0.842 and 0.829 ( P< 0.05) for cortisol and CK, BT and ECI of trailer, respectively. In conclusion, we state that PA reactivity is a physiological response for the diagnosis of stress of piglets transported. Further research will refine this technique in order to make this non-invasive acquisition method more practical and adaptable to different transport conditions.