WEANING OF PIGS RAISED IN SOW-CONTROLLED AND IN CONVENTIONAL HOUSING SYSTEMS .2. BEHAVIOR STUDIES AND CORTISOL-LEVELS

An alternative weaning system (sow-controlled, SC), where the sows cou ld leave the lactation pens at will and meet in a common pen, but the pigs could not, was studied and compared to a conventional system (CON V) where each pen housed a sow and her litter. The trial period began a week after farrowing when each system received 4 sows and litters, a nd stopped 4 weeks after weaning. The pigs had access to creep feed an d were weaned at 5 weeks of age when the sows were moved. Twenty-two S C and 23 CONV litters were studied. Behaviour studies showed that the SC sows spent considerably less time with their pigs during the later part of the lactation period. Similarly, the number of nursing bouts p er day was reduced and some sows more or less weaned their pigs before time. There were indications that the CONV sows were more disturbed b y the pigs than the SC sows were. Early after weaning, the SC pigs ten ded (p = 0.058) to have more observations of ''eating dry feed'' as co mpared to the CONV pigs. Piglet plasma cortisol levels increased with age, but no significant difference in the levels between pigs in the t wo systems was found. The greatest increase was observed in the week a fter weaning.