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Mixed Management in Growing and Finishing Pigs: Impacts on Social Behavior and Judgment Bias
by
, and
Angela Cristina da Fonseca de Oliveira
1,2,
Leandro Batista Costa
1,2,*
,
Saulo Henrique Weber
1
and
Antoni Dalmau
3
1
Graduate Program in Animal Science, School of Medicine and Life Sciences, Pontifícia Universidade Católica do Paraná, Curitiba 80215-901, PR, Brazil
2
Monohub—Research Group for Monogastric Animals, Pontifícia Universidade Católica do Paraná, Curitiba 80215-901, PR, Brazil
3
Institut de Recerca i Tecnologia Agroalimentàries—IRTA, Porcine Control and Evaluation, 17121 Monells, Spain
*
Author to whom correspondence should be addressed.
Animals 2025, 15(19), 2893; https://doi.org/10.3390/ani15192893
Submission received: 7 August 2025
/
Revised: 1 September 2025
/
Accepted: 26 September 2025
/
Published: 3 October 2025
(This article belongs to the Special Issue Effects of Housing Conditions and Management Practices on Pig Production and Welfare)
Simple Summary
Understanding how pigs respond to social and environmental challenges is essential to improve their welfare in farming systems. In this study, we investigated how mixing unfamiliar pigs and testing them in different contexts influenced their behavior and cognitive responses. Ninety-six pigs were allocated to groups, with some experiencing social stress by being mixed with unfamiliar conspecifics. We evaluated open field, food motivation, and judgment bias tasks. Gilts showed more signs of fear and caution in unfamiliar situations than barrows, taking longer to interact with food and to complete learning tasks. These results suggest that both previous social stress and sex can affect how pigs explore and make decisions. Such insights can guide improvements in welfare-oriented management on commercial farms.
Abstract
Intensive pig production practices may shape cognition and behavior. We evaluated whether repeated regrouping (mixing) and gender (gilts vs. barrows) affect social interactions, fear-related responses, and affective state. A total of 96 growing pigs were separated into two treatments: control—pigs that were mixed once during the growing–finishing period; and social stress—pigs that were mixed thrice during the growing–finishing period. Social and non-social behaviors were directly noted, and four behavioral tests were conducted: open field, novel object, couples, and judgment bias tests. The statistical analysis compared gender and treatment, and p-values ≤ 0.05 were considered significant. Females stayed longer in the test pen entrance area during the novel object test and barrows spent more time at the feeder and defecated more during the couples’ test. With regard to the judgment bias test, females took longer to be considered trained in the discriminatory learning task and presented a “pessimistic judgment” during the ambiguous cue. Our results suggest that gender influences judgment bias in pigs and can influence social and non-social behavior, which may reflect a negative affective state with implications for their welfare and management.
