A Randomized Clinical Trial Evaluating Metabolism of Colostral and Plasma Derived Immunoglobulin G in Jersey Bull Calves

Pipkin, K.M.; Hagey, J.V.; Rayburn, M.C.; Chigerwe, M.

The major finding in this study was the rapid decrease in serum IgG concentrations to those consistent with FPI in the PL group calves within the first 12 h after transfusion. Although the median serum IgG concentration reached concentrations consistent with adequate transfer of immunity (serum IgG concentrations ≥1,000 mg/dL) at 6 h after plasma transfusion, the concentrations were not maintained beyond 6 h. The halflife of plasma derived IgG was only 4.4 d compared to 17.1 d for colostral derived IgG. The median IgG concentrations indicative of FPI after 6 h and the short half-life of plasma derived IgG in the PL group indicated that the rate of catabolism of plasma derived IgG was higher compared to colostral derived IgG. Calves in the CL group maintained serum IgG concentrations consistent with adequate transfer of immunity during the 7-d study period. Fecal IgG concentrations were not different between the 2 groups except at 5 d of age when the CL group had higher fecal concentrations. Thus, fecal IgG concentration did not explain the fate of the rapidly decreasing serum IgG in the PL group. There are 2 possible explanations for the insignificant differences in the fecal IgG concentrations between the 2 groups before 5 d of age. First, results of studies in human patients with active or benign inflammatory bowel diseases 15 and clinical healthy dogs 9 suggested that fecal immunoglobulin determinations tests were less reliable because of lower detection rates (<0.01 to 35.5%). In the study in humans with active or benign inflammatory bowel disease, complete intestinal lavage was recommended for detection of fecal IgG. 15 Secondly, detection of IgG by SRID is based on the binding of the IgG molecule to the anti-bovine IgG in the agarose gel. 16 Consequently, destruction of the IgG binding site during preparation of fecal samples for IgG determination will result in lower detection rates of fecal IgG. The physiological mechanism resulting in increased catabolism of plasma derived IgG may be similar to the mechanism suggested studies of humans. 7 The studies 7 indicated that IgG aggregates formed during plasma preparation might activate complement after transfusion resulting in increased catabolism of IgG.