O'Connor, E. A., Parker, M. O., McLeman, M. A., Demmers, T. G. M., Lowe, J. C., Cui, L., …Abeyesinghe, S. M. The impact of chronic environmental stressors on growing pigs, Sus scrofa (Part 1): stress physiology, production and play behaviour. Animal, 4(11), 1899-1909. https://doi.org/10.1017/s1751731110001072