Biological half-life of ovine antibody in neonatal lambs and adult sheep following passive immunization.

Neonatal lambs and adult wethers were passively immunized with ovine antibody directed against ovalbumin or Brucella abortus. Estimates for the biological half-lives of the antibodies ranged from 18 to 24 days in neonatal lambs and 12 to 17 days in adult wethers. The evidence suggested that both normal and immunosuppressed wethers which were passively immunized with serum antibody catabolized this antibody at a faster rate than did neonatal lambs. The data provided no support for the hypothesis that the growth factors and immunomodulatory factors, which are known to be present in colostrum, can influence the biological half-life of homologous antibody following passive immunization.