AUTHOR=Steinerová Karolína , Krause Annika , Parker Sarah E. , Seddon Yolande M. TITLE=Exploring the effect of play on heart rate variability as a measure of positive emotional states in pigs JOURNAL=Frontiers in Veterinary Science VOLUME=12 YEAR=2025 URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2025.1518153 DOI=10.3389/fvets.2025.1518153 ISSN=2297-1769