For the sow, however, additional floor heating resultsin thermal stress, at least when limited opportunity is available for thermoregulatory behavior (Malmkvist etal., 2009). In comparison with an unheated control group, floor heating in the whole pen floor until 2 d after birth of first piglet (BFP) acted as a stressor, resulting in increased concentrations of plasma cortisol around parturition.There were, however, no concurrent changes in sow plasma oxytocin, indicators of birth problems, or behavior