“…During lactation food intake increases enormously (Johnson et al, 2001a) and conspicuously reaches a plateau in late lactation that is resistant to attempts to breach it by imposing additional workloads on the female, for example, by manipulating litter size or pup demands (Hammond and Diamond, 1992;Johnson et al, 2001a;Laurien-Kehnen and Trillmich, 2003;Duah et al, 2013), by making females simultaneously pregnant (Johnson et al, 2001c), or by forcing them to run to obtain their food (Perrigo, 1987;Zhao et al, 2013a). However, when lactating animals are placed in the cold, they are able to eat significantly more than at room temperature Hammond and Kristan, 2000;Johnson and Speakman, 2001;Rogowitz, 1998;Zhang and Wang, 2007), and conversely when kept in hot conditions their maximal intake declines (Król and Speakman, 2003a;Wu et al, 2009;Yang et al, 2013). This effect could be explained either by the HDL theory, the summed peripheral demands idea or temperature-dependent variations in pup energy demands.…”