The identification of behavioural key features and their incorporation into a housing design for pigs.

An ethological approach is presented which aims at meeting the welfare requirements of domestic pigs by satisfying their motivations and behavioural needs. Based on the causation of behaviour, welfare may be defined by motivational balance and behavioural needs by environmental and behavioural key features that are essential for the performance of behavioural sequences. Ethological minimum requirements were determined from observations of adult and juvenile large-white pigs in semi-natural enclosures, in increasingly restricted and in conventional conditions. Obligatory features in the environment which consistently enabled the pigs to perform their frequent or regular sequences of behaviour were the design factors for the enriched pens. Each is composed of a nesting, an activity and a rooting area and includes a corridor connecting 4 neighbouring pens. Such an unit houses 4 familiar sows with their fattening offspring, a boar and replacements. Basic features of social structure of the outdoor reference groups were maintained in such pig families. The social contacts in stable family groups enhance the synchrony of heats and lactational oestrus. Thus 2.3 litters/year may be obtained if sows are well fed before mating. As there is no weaning check, the growers reach bacon weight for market around 155 days of age. The system shows, what basic ethological research may contribute to reach practical housing conditions which meet the main behavioural requirements of a species.