In the first-litter sows lower serum levels were found for all three Ig classes as compared to multiparous sows. The same was true for IgA in lacteal secretions and in piglet serum during the first days of life, while no differences were found for IgG levels. In contrast to these findings, IgM levels were found to be higher in lacteal secretions of first-litter sows and in piglet serum during the first days of life as compared to their counterparts. From three weeks after birth Igs found in piglet serum mainly originate from de novo synthesis. In this period piglets of first litter sows showed a higher IgA level up to the 6th week of life and higher IgG and IgM levels up to the end of the investigation period. Results are discussed in terms of maternal-neonatal immune regulation, focussing on the apparent suppressive role of maternally-derived IgG on total de novo Ig synthesis by suckling piglets.