Immunoglobulin IgG1 Metabolism in New Born Calves

Abstract

The half-life of IgGl immunoglobulin was measured in six neonatal calves following a meal of iodine-125 labeled IgGl in colostrum derived from their dams. The half-life as measured by the decrease in plasma concentration of IgGl was 19.9 ± 1.9 days. However, the half-life as measured by the disappearance of [iodine-125] IgG1 from the plasma was 11.5 ± .6 days. The latter value is closer to the true half-life because it is not affected by endogenous production of IgGl by the tissues of the young calf. A decrease in the specific activity of plasma [iodine-125] IgGl with time representing the body “pool” of IgGl (half-life 25.8 ± 6.1 days) suggests that the calf from birth to about 20 days of age is capable of synthesizing a significant amount of IgGl immunoglobulin. © 1977, American Dairy Science Association. All rights reserved.