Social status and housing factors affect reproductive performance of pregnant sows in groups

Janeen L. Salak-Johnson

Research output: Contribution to journalReview articlepeer-review


Group-housing systems for pregnant sows are considered a welfare-promoting alternative to the individual stall. A major concern associated with pregnant sows housed in group pens is increased aggression at mixing and at feeding, which may cause chronic stress among some of the sows in the group due to low feed intake and social stress. Prolonged activation of the stress axis, based on elevated cortisol levels, may inhibit or impair reproductive success via disruption of the reproductive axis. Mixing sows into groups shortly after insemination evokes a stress response, which may affect fertilization and implantation due to sustained, elevated cortisol levels that disrupt reproductive processes. Yet, most studies reported minimal effects of group housing sows during pregnancy on reproduction or cortisol-related stress response. Differences between housing systems—in terms of group size, floor-space allowance, feeding system, and genetics—could account for these unexpected results. Indeed, interrupted feed intake, especially in early pregnancy, and sustained aggression in late pregnancy are two unfavorable social stresses that deserve special attention in order to achieve good reproductive performance. Unfortunately, most studies do not consider other factors, such as social rank and parity, which may interactively affect reproductive success and aggressive behavior of sows, especially in group-pen systems.

Original languageEnglish (US)
Pages (from-to)905-913
Number of pages9
JournalMolecular reproduction and development
Issue number9
StatePublished - Sep 2017


  • aggression
  • group pens
  • pregnancy
  • stress

ASJC Scopus subject areas

  • Genetics
  • Developmental Biology
  • Cell Biology


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