Long-Distance Transport of Finisher Pigs in the Iberian Peninsula: Effects of Season on Thermal and Enthalpy Conditions, Welfare Indicators and Meat pH.

Genaro C Miranda-De La Lama,Rubén Bermejo-Poza,Nora Formoso-Rafferty,Morris Villarroel,Pilar Barreiro,Malcolm Mitchell

doi:10.3390/ani11082410

Abstract

Simple SummaryLong-distance transport in the global swine industry is more the rule than the exception. We tested the impact on the rates of temperature change and air enthalpy on the stress response and muscle pH in pigs subjected to long-distance travel from Spain to Portugal performed in the summer and winter. We found that winter journeys are more adverse for the animals because during the journey, abrupt variations in rates of temperature change and air enthalpy caused a marked physiological stress response and effects on the meat pH after 45 min. These results indicate the need to develop new environmental control strategies that mitigate abrupt temperature changes during travel to attenuate the biological cost of such long-distance transport on the animals.Current legislation in the European Union places limits on live pig transport according to outside temperature, but less is known about the effects of sudden changes in the thermal microenvironment in trailers, particularly during long-distance transport. In this study, we measured the temperature and relative humidity inside livestock vehicles carrying 1920 Spanish finisher pigs (live weight 100 kg and 240 animals per journey) during eight long-distance (>15 h) commercial journeys to slaughter from northern Spain to Portugal in the summer and winter. Here, we report the rate of change in the air temperature (°C × min−1) and air enthalpies in the transport vehicle (kg water kg dry air-1). At sticking, blood samples were taken for to measure cortisol, glucose, and creatine kinase (CK) as stress response indicators, and the meat pH after 45 min and the pH after 24 h were also determined. The rate of change in the air temperature and enthalpy was higher inside the livestock vehicle during the winter months and was positively related with higher cortisol and glucose levels and lower pH after 45 min (p < 0.05). It is proposed that the rate of temperature change and air enthalpy represent useful integrated indices of thermal stress for pigs during transport.

Highlights

Pig production in the European Union is increasingly industrialized and specialized [1], with the EU being the second largest pig producer in the world, with 24.1 million tons of pork produced in 2019 [2]
The results suggest that enthalpy during transport can be a Overall, the results suggest that enthalpy during transport can be a useful non-invasive useful non-invasive indicator of animal welfare
The results show that the pH after 45 min was affected in the pigs that were transported in the winter, the average values remained within normal ranges

Summary

Introduction

Pig production in the European Union is increasingly industrialized and specialized [1], with the EU being the second largest pig producer in the world, with 24.1 million tons of pork produced in 2019 [2]. Extreme ambient temperatures during long-distance journeys are considered as one of the most important risk factors for dead on arrivals, non-ambulatory animals, skin lesions, and carcass downgrading, especially when microclimate conditions are outside of the optimal thermal comfort zone for pigs [7]. These thermal conditions may be complex and result from the interaction of several factors such as external climatic conditions, heat and water production from the animals, ventilation regimes, distribution and flow rates, and additional external sources of heat and/or moisture [8]

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