The Role of Play Behaviour to Enhance Pig Welfare and Resilience and its Implications for the Swine Industry
Date
2025-03-28
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0000-0002-6621-893X
Type
Thesis
Degree Level
Doctoral
Abstract
To maintain the societal license to operate intensive pig farming facilities, new concepts to enhance pig welfare practices without compromising production efficiency and cost must be found. Positive welfare should be prevalent over time to demonstrate pigs experience a good quality of life. Play behaviour is a potential indicator of positive welfare, as it is associated with pleasurable states and naturally occurs in piglets. The objective of this thesis was to investigate whether play behaviour can be used as a tool by the swine industry to promote positive welfare on conventional farms, delivering benefits for both pigs and producers. Chapter 3 served as a proof of concept, exploring whether play can be promoted and sustained in pigs beyond the natural period of its expression in commercial settings by providing extra space in a playpen and/or destructible enrichment. Chapters 3, 4 and 5 investigated whether play is positive for pigs using behavioural indicators of positive experiences in Chapter 3, with cognitive bias testing (CBT) in Chapter 4, and heart rate variability (HRV) parameters in Chapter 5. Chapter 6 examined whether pigs reared with regular play opportunities from birth develop enhanced disease resilience against Porcine Reproductive and Respiratory Syndrome Virus (PRRSV). Play was successfully stimulated in pigs throughout the grow-finish phase with the use of destructible enrichment, even without extra space, when novelty was continuously renewed (intermittent provision, enrichment rotation) (Chapter 3). Regular play promotion during the finishing stage improved learning and trainability for CBT, indicating positive effects of play opportunities on decreased fear in novel and mildly aversive situations (Chapter 4). HRV parameters indicative of vagal tone (RMSSD) and sympathovagal balance (SDNN) were increased during and immediately after play, suggesting contribution to positive emotional states (vagal activation) and the influence of physical activity involved in play (sympathetic activation) (Chapter 5). Pigs reared with play opportunities from birth had fewer skin lesions after transport, were less affected by PRRSV (less severe respiratory distress and sickness behaviour) and performed better during infection, supporting the link between positive emotional states and enhanced resilience (Chapter 6). These results indicate that regular play promotion improves adaptability and coping during common production challenges. Play is likely to be rewarding for pigs, regardless of which emotional state (negative/positive) it stems from, contributing to the development of an indicator of positive emotions. With further refinement for practical and cost-efficient application on commercial farms, the concept of promoting positive experiences through play has the potential to be used as a tool to promote positive welfare for intensively farmed pigs.
Description
Keywords
Pig, Swine, Play Behaviour, Positive Emotions, Positive Animal Welfare, Environmental Enrichment, Disease Resilience, Animal-friendly Husbandry System, Farm Animals
Citation
Degree
Doctor of Philosophy (Ph.D.)
Department
Western College of Veterinary Medicine
Program
Animal Science