The pig is a curious ungulate. It is the only one which builds a nest prior to parturition, gives birth to large litters of altricial young, and does not lick the young after birth, just to mention some oddities. I studied the maternal behaviour of pigs in semi-natural enclosures for seven years (Jensen, 1988; Jensen et al 1993) and the results provide some insights into the specific welfare requirements of the sow and its offspring.

In 30 Swedish Landrace sows, more than 100 farrowings and subsequent mother-young interactions were observed in three enclosures measuring 7,12 and 13 hectares. The animals were fed daily full rations of concentrate and had access to shelters. In addition, series of experiments have been carried out under controlled laboratory conditions to test and validate some of the findings (for example Jensen, 1993).