SPECIFIC IMMUNOLOGICAL-UNRESPONSIVENESS FOLLOWING ACTIVE PRIMARY RESPONSES TO PROTEINS IN THE WEANING DIET OF PIGLETS

Young piglets weaned onto soya diets frequently develop diarrhoea whic h may have a dietary and/or immunological component. Piglets abruptly weaned onto soya at 3 weeks of age developed levels of serum IgG anti- soya antibodies almost comparable to those induced by injection with s oya protein in adjuvant at 7 weeks. In the piglets primed by feeding, no significant further increase in antibody occurred after subsequent systemic injection. In contrast, secondary responses were observed in age-matched animals, previously primed by injection, and primary respo nses were obtained in previously naive piglets. The results demonstrat e the development of specific unresponsiveness to soya proteins in neo nates fed soya, despite the occurrence of an initial vigorous immune r esponse to the fed protein.