Transfer of immunoglobulins IgG, IgA and IgM to lacteal secretions in the parturient sow and their absorption by the neonatal piglet

Abstract

Porcine immunoglobulins IgG, IgA and IgM have been isolated and used in immunochemical studies of the secretion of these components into colostrum and then intestinal absorption by the neonatal piglet. Assays on 9 samples of colostrum from different sows indicated that 63.6 ± 8.6% of the whey protein was accounted for by the immunoglobulins which comprise IgG (79.7 ± 16.9%), IgA (14.05 ± 7.35%) and IgM (6.27 ± 2.35%). Immunoglobulins IgG and IgM occur in the colostrum at approx. 2–3 times the level in serum but the level of IgA in colostrum was 3–11 times greater than in serum. Molecular size characteristics of the immunoglobulins in sow serum and colostrum have been obtained in Sephadex G-200 gel filtration studies. Colostral IgA is eluted in a wide range of molecular sizes in the gel filtration pattern but the high molecular weight forms are predominant. A serum component with a sedimentation constant ( s 20, w ) of 17.8 which is antigenically distinct from IgM but gives reactions of identity with IgG, also appears in colostrum. Precolostral piglet serum was almost entirely deficient of immunoglobulins. A component having shared antigenic determinants with IgG was present in concentrations less than 50 μg/ml. Studies of 6 litters of piglets indicated that immunoglobulins IgG, IgA and IgM were absorbed from the colostrum. The post colostral serum concentrations of IgG and IgM were mainly similar to adult levels, whilst IgA generally exceeded adult levels, in some cases by as much as 3–4 times.