Effects of microclimate during transport on physiological indicators of market pig welfare: a systematic review with meta-analysis
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 uncle...
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| Format: | Article |
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Frontiers Media S.A.
2025-08-01
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| Series: | Frontiers in Veterinary Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fvets.2025.1657185/full |
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| author | Rick O. Hernandez Artur O. Rocha Chao Cai Marisa Erasmus Jay S. Johnson Luiz F. Brito |
| author_facet | Rick O. Hernandez Artur O. Rocha Chao Cai Marisa Erasmus Jay S. Johnson Luiz F. Brito |
| author_sort | Rick O. Hernandez |
| collection | DOAJ |
| description | 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 (β = 0.93 ± 0.12; p < 0.01). However, ambient relative humidity showed a lower magnitude association with trailer relative humidity (β = 0.51 ± 0.00; p < 0.001). Adverse microclimate conditions represented by high enthalpy (H) were associated with increases in creatine kinase (β = 3,715 ± 94.11; p < 0.001), lactate (β = 0.45 ± 0.12; p < 0.001), skin temperature (β = 0.10 ± 0.03; p < 0.01), and blood cortisol (β = 0.16 ± 0.08; p < 0.05). Short trips (<119 min) increased skin lesion score (β = 2.58 ± 0.43; p < 0.01), and medium trips (120–420 min) increased skin temperature (β = 6.36 ± 0.45; p < 0.001) and reduced cortisol levels (β = –11.36 ± 2.59; p < 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. |
| format | Article |
| id | doaj-art-eadec16d519949639fae52849782dce6 |
| institution | DOAJ |
| issn | 2297-1769 |
| language | English |
| publishDate | 2025-08-01 |
| publisher | Frontiers Media S.A. |
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| series | Frontiers in Veterinary Science |
| spelling | doaj-art-eadec16d519949639fae52849782dce62025-08-20T02:57:30ZengFrontiers Media S.A.Frontiers in Veterinary Science2297-17692025-08-011210.3389/fvets.2025.16571851657185Effects of microclimate during transport on physiological indicators of market pig welfare: a systematic review with meta-analysisRick O. Hernandez0Artur O. Rocha1Chao Cai2Marisa Erasmus3Jay S. Johnson4Luiz F. Brito5Department of Animal Sciences, Purdue University, West Lafayette, IN, United StatesDepartment of Animal Sciences, Purdue University, West Lafayette, IN, United StatesPurdue University Libraries and School of Information Studies, Purdue University, West Lafayette, IN, United StatesDepartment of Animal Sciences, Purdue University, West Lafayette, IN, United StatesDivision of Animal Sciences, College of Agriculture, Food and Natural Resources, University of Missouri, Columbia, MO, United StatesDepartment of Animal Sciences, Purdue University, West Lafayette, IN, United StatesDuring 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 (β = 0.93 ± 0.12; p < 0.01). However, ambient relative humidity showed a lower magnitude association with trailer relative humidity (β = 0.51 ± 0.00; p < 0.001). Adverse microclimate conditions represented by high enthalpy (H) were associated with increases in creatine kinase (β = 3,715 ± 94.11; p < 0.001), lactate (β = 0.45 ± 0.12; p < 0.001), skin temperature (β = 0.10 ± 0.03; p < 0.01), and blood cortisol (β = 0.16 ± 0.08; p < 0.05). Short trips (<119 min) increased skin lesion score (β = 2.58 ± 0.43; p < 0.01), and medium trips (120–420 min) increased skin temperature (β = 6.36 ± 0.45; p < 0.001) and reduced cortisol levels (β = –11.36 ± 2.59; p < 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.https://www.frontiersin.org/articles/10.3389/fvets.2025.1657185/fullmicroclimate stresspig transportpig welfareheat stresstransport microclimate |
| spellingShingle | Rick O. Hernandez Artur O. Rocha Chao Cai Marisa Erasmus Jay S. Johnson Luiz F. Brito Effects of microclimate during transport on physiological indicators of market pig welfare: a systematic review with meta-analysis Frontiers in Veterinary Science microclimate stress pig transport pig welfare heat stress transport microclimate |
| title | Effects of microclimate during transport on physiological indicators of market pig welfare: a systematic review with meta-analysis |
| title_full | Effects of microclimate during transport on physiological indicators of market pig welfare: a systematic review with meta-analysis |
| title_fullStr | Effects of microclimate during transport on physiological indicators of market pig welfare: a systematic review with meta-analysis |
| title_full_unstemmed | Effects of microclimate during transport on physiological indicators of market pig welfare: a systematic review with meta-analysis |
| title_short | Effects of microclimate during transport on physiological indicators of market pig welfare: a systematic review with meta-analysis |
| title_sort | effects of microclimate during transport on physiological indicators of market pig welfare a systematic review with meta analysis |
| topic | microclimate stress pig transport pig welfare heat stress transport microclimate |
| url | https://www.frontiersin.org/articles/10.3389/fvets.2025.1657185/full |
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