Production of foetally stimulated lymphocytotoxic antibodies by primiparous cows.

Serum samples from groups of heifers at different pregnancy-related stages (preconception, month of pregnancy, and postpartum) were examined for the presence of lymphocytotoxic antibodies. Only a few weak and transitory antibodies were observed before or during the first pregnancy. These did not appear to be foetally stimulated. Strong or medium strength antibodies were detected in first or second month postpartum samples from 8 of 27 heifers (30%). The reactive sera were in every case reactive with the offspring of the cows from which the respective sera were collected.