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Regular outdoor access decreases stress with positive effects on the health of growing pigs raised on a conventional farm

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Abstract

Conventional pig production systems are characterized by fully slatted floors and space restrictions, hindering pigs from foraging and roaming. In contrast, providing pigs with outdoor access allows them to express a wide range of behaviors, but might challenge their health. In this context, we hypothesized that giving pigs regular outdoor access might lower stress exposure with positive impacts for health and welfare. A total of 145 male and 148 female pigs, housed in a conventional barn, were provided (OUT) or not (IN) with access to a grassy paddock twice a week from the age of 77 days to slaughter. The OUT pigs had lower salivary cortisol levels than the IN pigs. Regular access to a pasture also lowered the severity of body lesions. While it had no consequences on animal growth, it was associated with a reduced frequency of diarrhea in pigs. Despite lower leukocytes counts in the OUT pigs compared to the IN ones, higher proportion of the OUT pigs developed humoral response against L. intracellularis. Thus, providing regular access to a paddock for growing pigs had positive impacts on their health and welfare, with no consequence on their performance.

Data availability

The data generated and analyzed in the current study are available in Supplementary Table 1.

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Acknowledgements

We sincerely thank Charline Niort and Grégory Khelifi from the GenESI research facility as well as Morgane Rémond, the veterinarian of the farm. We also gratefully acknowledge everyone at IECM, particularly the interns for their work on sample analyses, as well as Laboniris for technical support. We express our deep gratitude to INRAE, especially the SANBA Metaprogram, for supporting this work. We acknowledge Labocea (Ploufragan, France) for the rapid analyses of L. intracellularis in feces using PCR.

Funding

AJ was supported by the INRAE through her PhD fellowship. The study was funded by the INRAE Metaprogram SANBA through the PANORAMA project, supervised by CT and JH.

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Authors and Affiliations

  1. Oniris, INRAE, IECM, Oniris la Chantrerie, 101 route de Gachet, 44300, Nantes, France

    Anissa Jahoui, Julie Lion, Solenn Gavaud, Karine Haurogné, Blandine Lieubeau & Julie Hervé

  2. PEGASE, INRAE, Institut Agro Rennes Angers, 16 le clos, 35590, Saint Gilles, France

    Anissa Jahoui & Céline Tallet

  3. INRAE, GenESI, 86480, Rouillé, France

    Franck Guiraud, Tony Terrasson & Stéphane Ferchaud

Authors

  1. Anissa Jahoui
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  2. Julie Lion
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  3. Franck Guiraud
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  4. Solenn Gavaud
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  5. Karine Haurogné
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  7. Stéphane Ferchaud
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  8. Blandine Lieubeau
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  9. Céline Tallet
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  10. Julie Hervé
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Contributions

BL, CT, and JH designed the experiment. CT and JH supervised the project. AJ, FG, JL, SG, KH, TT, SF, BL, and JH conducted the experiments. AJ, JL, KH, BL, and JH analyzed the results. AJ, BL, and JH interpreted the results and wrote the main manuscript text. All authors have read and approved the submitted version of the manuscript.

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Correspondence to
Julie Hervé.

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Supplementary Material 1

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Jahoui, A., Lion, J., Guiraud, F. et al. Regular outdoor access decreases stress with positive effects on the health of growing pigs raised on a conventional farm.
Sci Rep (2026). https://doi.org/10.1038/s41598-026-38461-3

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  • DOI: https://doi.org/10.1038/s41598-026-38461-3

Keywords

  • Outdoor access
  • Pig
  • Health
  • Cortisol
  • Immunity

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