Transporte de suínos em clima tropical: bem-estar animal, estresse térmico e ventilação na carga

Abstract

Divided into three chapters, this thesis addresses the aspects of animal welfare and ambience in pig transport. In Chapter I, the objective was to identify the heat zones of the load and to evaluate its relationship with the thermal stress of pigs. Four commercial loads were monitored in journeys of 170 km, with 192 pigs sampled (48 per load and 4 per compartment) to collect physiological indicators of heat stress. Geostatistics and computational fluid dynamics (CFD) techniques were applied to understand the dynamics of heat zones and the patterns of wind flow within the load. It was possible to verify, during transport, the formation of heat zones with different magnitudes along the load, due to the dynamics of ventilation. A thermal core was also detected in the frontal region of the trailer, associated with the highest values of respiratory frequencies and salivary cortisol of the pigs. In Chapter II, the objective was to evaluate the individual and combined effects of distances (30 and 170 km) and shifts (morning, afternoon and night) of transport in pre-slaughter losses and in the welfare of pigs. 684 pigs were used, from 19 journeys and subsequent registration of the load enthalpy profile, physiological responses and production losses. The transport in the afternoon shift was more detrimental to the welfare of the pigs and more susceptible to the occurrence of losses, especially over short distances. Therefore, it was found that the relationship between the stress of the pigs and the transport distance did not behave in a linear way. In chapter III, the hypothesis was tested that the use of devices to direct the wind flow into the load could reduce the thermal energy and the accumulation of moisture contained in the load compartments. For this, two prototypes were developed (airfoil and deflector). The CFD and 3D modeling techniques were applied to evaluate the performance of the prototypes. The use of the airfoil increased the wind flow of the load and reduced the thermal energy (-3.9%) and humidity (-6.0%) of the compartments (both, P <0.001). The use of deflector reduced the thermal energy (-3.04%), but resulted in the translocation of thermal core to the frontal region of the upper deck of the load. The results of the simulations showed that both devices optimized the ventilation of the load. The use of the airfoil performed better in this process; however, this effect was enhanced by the association with the use of the deflector on the side of the trailer.