Current Diagnostic Methods for Assessing Transfer of Passive Immunity in Calves and Possible Improvements: A Literature Review

Abstract

Several direct or indirect methods can be used to assess immunoglobulin G (IgG) concentrations in calves, which evaluates the transfer of passive immunity (TPI). Radial immunodiffusion (RID) is the gold standard method to measure serum IgG in bovines. Previous studies have shown that colostrum provides several molecules in addition to immunoglobulins, which play an important role in the passive immunity of the calf. However, no studies have yet determined the level of interference of these components in the immunity, health and survival of calves. In this sense, the objective of this study is to review the methods of evaluation available for the laboratory and field diagnosis of TPI in calves and discuss the main aspects of each technique. Several methods available for TPI evaluation in calves may provide insights into the various components of colostrum involved in passive immunity.

Comparison of turbidometric immunoassay, refractometry, and gamma‐glutamyl transferase to radial immunodiffusion for assessment of transfer of passive immunity in high‐risk beef calves

“…Thus, it is likely that GGT is present in and actively absorbed from at least some colostrum‐based replacement products depending on heat treatment settings used. Regardless, based on our results and consistent with previously published reviews, 20,26 the use of GGT to differentiate the level of TPI achieved in beef calves does not appear to be justified.…”

“…Turbidimetric immunoassays have several potential advantages regarding measurement of TPI in calves at the individual as opposed to herd level. The results of these tests are quantitative and directly estimate the actual IgG concentration; TP or Brix refractometry are indirect measures of IgG 20 . Previously marketed TI kits that are no longer commercially available in the United States have been documented in the literature to have excellent ( R 2 = 0.98) correlation with RID test results in dairy calves with serum IgG levels ranging from 4.60 to 36.40 g/L 10 ; in dairy and beef calves <2 weeks of age that test was also shown to have good sensitivity and specificity for detection of IgG <10.0 g/L 11 .…”

“…While the TI and RID demonstrated good correlation, a very large and clinically relevant bias was noted between the 2 testing modalities. Radial immunodiffusion has long been considered the reference standard for assessment of serum IgG levels in calves (recently reviewed in reference 20). However, both the RID and TI tested in our study rely heavily on the standards provided with the test kits to determine the result for each individual sample.…”

“…In otherwise healthy beef calves less than 18 days of age with a mean serum IgG of 33.16 g/L (range, 5.20‐49.50 g/L), serum GGT demonstrated a poor correlation with IgG results 8 . Interestingly, no studies to date have evaluated the effect of the use of colostrum replacement products on absorption of GGT despite review articles stating that GGT absorption from colostrum is interrupted by pasteurization or use of colostrum replacers 20 . In this review, the article referenced for this statement only tested synthetic milk (the production of which was not described) and boiled cow's milk, not pasteurized colostrum 24 .…”

“…16 Our data support this suggestion as we observed good differentiation of cutoff values for TP in maternal colostrum-fed calves that are similar to those previously reported, but poor differentiation in calves that received any amount of colostrum replacement product. In beef calves, Gamsjäger et al 19 and Akkose et al 22 20 In this review, the article referenced for this statement only tested synthetic milk (the production of which was not described)…”