Influence of low ambient temperatures on heat production and energy balance of single-housed growing pigs fed ad libitum: a comparison with group-housed pigs Nathalie Quiniou, Jean Noblet, Jaap van Milgen and Serge DuboisAnim. Res., 50 4 (2001) 325-333DOI: https://doi.org/10.1051/animres:2001134