Hernandez Rick O, Rocha Artur O, Cai Chao, Erasmus Marisa, Johnson Jay S, Brito Luiz F
Department of Animal Sciences, Purdue University, West Lafayette, IN, United States.
Purdue University Libraries and School of Information Studies, Purdue University, West Lafayette, IN, United States.
Front Vet Sci. 2025 Aug 7;12:1657185. doi: 10.3389/fvets.2025.1657185. eCollection 2025.
During transportation, microclimatic conditions can fluctuate significantly, affecting pigs' thermal comfort and leading to compromised welfare and production losses. Although numerous studies have examined the effects of heat stress during transport on pig welfare and meat quality, it remains unclear whether these effects persist across varying transport scenarios and environmental conditions. Therefore, this systematic review and meta-analysis evaluated the effects of microclimate during transport on physiological welfare indicators in market pigs and summarized methodologies for assessing microclimate in commercial settings. Following PRISMA guidelines, 21 studies from three databases were used. Meta-regression analyses assessed microclimatic effects and trip duration on physiological indicators, including ultimate pH (pHu), creatine kinase (U/L), lactate (mmol/L), skin lesion score (0-5), skin temperature (°C), and blood cortisol (ng/mL). The studies retrieved used different equations to determine temperature-humidity index and enthalpy to describe microclimate dynamics. Ambient temperature was significantly associated with trailer temperature ( = 0.93 ± 0.12; < 0.01). However, ambient relative humidity showed a lower magnitude association with trailer relative humidity ( = 0.51 ± 0.00; < 0.001). Adverse microclimate conditions represented by high enthalpy (H) were associated with increases in creatine kinase ( = 3,715 ± 94.11; < 0.001), lactate ( = 0.45 ± 0.12; < 0.001), skin temperature ( = 0.10 ± 0.03; < 0.01), and blood cortisol ( = 0.16 ± 0.08; < 0.05). Short trips (<119 min) increased skin lesion score ( = 2.58 ± 0.43; < 0.01), and medium trips (120-420 min) increased skin temperature ( = 6.36 ± 0.45; < 0.001) and reduced cortisol levels ( = -11.36 ± 2.59; < 0.01). In conclusion, trailer microclimates differ from ambient conditions and are strongly associated with physiological stress indicators in market pigs. Monitoring H may offer a more accurate representation of thermal load during transport, enabling threshold development for risk assessment. These consistent associations across diverse environments underscore the global nature of transport-related heat stress and the need for coordinated international welfare standards. Integrating compartment-level microclimate monitoring into transport protocols will improve welfare evaluation and support predictive risk models.
在运输过程中，微气候条件可能会大幅波动，影响猪的热舒适度，导致福利受损和生产损失。尽管众多研究已考察运输过程中的热应激对猪福利和肉质的影响，但尚不清楚这些影响在不同运输场景和环境条件下是否持续存在。因此，本系统综述和荟萃分析评估了运输过程中的微气候对上市猪生理福利指标的影响，并总结了商业环境中评估微气候的方法。遵循PRISMA指南，使用了来自三个数据库的21项研究。荟萃回归分析评估了微气候效应和行程持续时间对生理指标（包括最终pH值（pHu）、肌酸激酶（U/L）、乳酸（mmol/L）、皮肤损伤评分（0 - 5）、皮肤温度（°C）和血液皮质醇（ng/mL））的影响。检索到的研究使用不同方程来确定温度 - 湿度指数和焓以描述微气候动态。环境温度与拖车温度显著相关（ = 0.93 ± 0.12； < 0.01）。然而，环境相对湿度与拖车相对湿度的关联程度较低（ = 0.51 ± 0.00； < 0.001）。以高焓（H）表示的不利微气候条件与肌酸激酶升高（ = 3,715 ± 94.11； < 0.001）、乳酸升高（ = 0.45 ± 0.12； < 0.001）、皮肤温度升高（ = 0.10 ± 0.03； < 0.01）和血液皮质醇升高（ = 0.16 ± 0.08； < 0.05）相关。短途行程（<119分钟）会增加皮肤损伤评分（ = 2.58 ± 0.43； < 0.01），中途行程（120 - 420分钟）会增加皮肤温度（ = 6.36 ± 0.45； < 0.001）并降低皮质醇水平（ = -11.36 ± 2.59； < 0.01）。总之，拖车微气候与环境条件不同，且与上市猪的生理应激指标密切相关。监测焓可能更准确地反映运输过程中的热负荷，有助于制定风险评估阈值。这些在不同环境中的一致关联凸显了运输相关热应激的全球性以及制定协调一致的国际福利标准的必要性。将车厢级微气候监测纳入运输协议将改善福利评估并支持预测性风险模型。
