Secretion and composition of colostrum and milk.

Lacteal fluids contain antibodies of immunoglobulin (Ig) A, IgG, and IgM classes, and these proteins are complete and biologically active. Lymphocytic cells have also been demonstrated that are capable of an array of biological activity characteristic of similar cells in the blood. Lacteal fluids are rich in phagocytic cells that function less efficiently than do their corresponding blood cells.