Proceedings of the 5th International Conference on the Assessment of Animal Welfare at Farm and Group Level WAFL 2011 : Campbell Centre for the Study of Animal Welfare, University of Guelph, Guelph, Ontario, Canada, 8-11 August 2011 - Widowski, Tina.; Lawlis, Penny.; Sheppard, Kimberly. (Wageningen Academic Publishers, 2011)