[Passive immunization in neonatal piglets in natural rearing--effects of birth order, birth weight, litter size and parity].

603 neonatal piglets (German Landrace) were investigated for passive immunization affected by birth order, birth weight, litter size and parity. Concentrations of immunoglobulins in the blood serum of piglets on the first day of life served as measure for passive immunization. Blood samples were drawn at 12, 18 and 24 hours post partum. Quantitative measurements of immunoglobulin classes were carried out by radial immunodiffusion. There was a significant effect of birth order, because of the rapid changes in colostrum composition between onset of birth and the last piglet of each litter. The effect of birth weight was only partly significant and different for the immunoglobulin classes. There was no significant effect of litter size on passive immunization. Parity had a significant positive effect on IgG- and IgA-concentrations in sow's colostrum with litter two to six, parity 1 and 2 lead to highest IgM concentrations in the blood serum of piglets.