Factors Affecting Trailer Thermal Environment Experienced by Market Pigs Transported in the US

Abstract

Simple SummaryTransport conditions can be a challenge for pigs being transported to market. In this study, 40 trips of commercial market pigs transported from the farms to an abattoir were monitored for thermal conditions including temperature and relative humidity in order to better understand thermal variability within the trailer during transport. Variation in thermal environment inside the pig transport trailer was used as an indicator of ventilation pattern during various weather conditions. During cold weather, the front top and bottom zones were warmer than in the rest of the trailer, indicating less ventilation toward the front of the trailer. Conditions were more uniform throughout the trailer for hot temperatures, indicating sufficient ventilation to limit temperature rise. Misting showed the potential to alleviate high temperatures, but resulted in higher THI conditions. No effect of boarding and bedding combination was observed for spatial distribution of trailer interior temperatures.AbstractExtreme weather conditions challenge pig thermoregulation during transport and are addressed by the National Pork Board (NPB) Transport Quality Assurance® (TQA) program that provides guidelines for trailer boarding, bedding, and misting. These guidelines are widely applied, yet very little is known about the microenvironment within the trailer. In this study, TQA guidelines (V4) were evaluated via extensive thermal environment measurements during transport in order to evaluate spatial variability and implications on ventilation pattern. Effects of trailer management strategies including bedding, boarding, and misting were examined and the trailer was monitored for interior temperature rise and THI responses within six separate zones. The trailer thermal environment was not uniformly distributed in the colder trips with the top front and bottom zones were the warmest, indicating these zones had the majority of outlet openings and experienced air with accumulated sensible and latent heat of the pigs. Relatively enhanced thermal environment uniformity was observed during hot trips, suggesting that ventilation patterns and ventilation rate were different for colder vs. warmer weather conditions. Misting applied prior to transport cooled interior air temperature, but also created high THI conditions in some cases. Neither boarding and bedding combinations in the TQA nor boarding position showed impacts on trailer interior temperature rise or spatial distribution of temperature inside the trailer.

Commercial straight-deck trailer vibration and microclimate conditions during market-weight pig transport during summer

“…Unlike temperature trends in the current study, the trailer section did not affect relative humidity measures during morning and afternoon transport. Xiong et al (2018) found that the humidity and humidity index did not vary among different potbelly trailer sections during mild, warm, and very hot weather conditions. During colder conditions, Morris et al (2021) found that fore and center sections of potbelly and straight-deck trailers had a 4.3%-greater relative humidity than the aft section.…”

Effects of driving style and bedding in pigs transported to slaughterhouse in different temperatures

“…Considering the time exposed to vibration, our study classifies the driving styles (normal driving style, average VDV total value: 8.5 m s –1.75 ; aggressive driving style, average VDV total value: 9.5 m s –1.75 ). Pigs are exposed to HT and LT during transportation, depending on the weather conditions [ 33 ]. Heat and cold stress can both negatively impact pig mortality and welfare [ 34 ].…”

Heat/Cold Stress and Methods to Mitigate Its Detrimental Impact on Pork and Poultry Meat: A Review

“…Xiong, Gates, and Green-Miller [61] (USA) analyzed the effects of the thermal category, trailer zones, and misting method (before the start of the trip) for mild, warm, and hot weather (16.7-35.3 • C) and cold weather (−10.6-7 • C) transport trips of market pigs. They found that the front top and bottom zones were warmer during cold weather than the rest of the trailer, indicating less ventilation toward the front.…”

“…Wang et al [62] offered another solution to reduce the adverse effects of HS during prolonged (>3 h) pre-slaughter transport of poultry in summer. Supplementation with resveratrol [61] at a dose of 400 mg/kg for 21 days or guanidine acetic acid at a dose of 1200 mg/kg for 14 days [49] before slaughtering broilers exposed to HS can help reduce the rate of glycolysis of PM muscles, which mainly contain glycolytic fibers [63], which can improve meat quality.…”