Short communication: Validation of methods for practically evaluating failed passive transfer of immunity in calves arriving at a veal facility

Abstract

Providing a sufficient quantity of high-quality colostrum to male and female calves soon after birth is critical to reduce the risk of disease and mortality. Practical tests have not been validated to determine failed passive transfer of immunity upon arrival at veal facilities. There are many challenges to validation, including the lack of information on the age of the calf and the high prevalence of dehydration. The objective of this study was to validate a semiquantitative IgG antibody test using whole blood and a digital refractometer using serum to determine passive transfer of immunity status. A total of 149 Holstein calves were evaluated upon arrival at a milk-fed veal facility for dehydration status and had blood drawn to evaluate passive transfer of immunity. Serum IgG determined by radial immunodiffusion was used as the gold standard for the validation of the tests, and a cut-off point of <1,000 mg/dL of IgG was used to indicate failed passive transfer of immunity. Serum total protein (STP) was evaluated using a digital refractometer (Misco Palm Abbe no. PA202x, Misco, Solon, OH), and a semiquantitative test (ZAPvet Bovine IgG test, NOWDiagnostics, Toronto, Ontario, Canada) was used on whole blood. A nonparametric receiver operating characteristic curve was generated to compare STP and IgG levels. Sensitivity, specificity, positive predictive values, and negative predictive values were calculated for STP and the semiquantitative IgG test. A total of 31 calves (21%) had serum IgG <1,000 mg/dL. Twelve percent of calves were showing signs of clinical dehydration when assessed upon arrival. The serum total protein (STP) was very well correlated with the concentration of IgG (R = 0.75). The STP cut point to determine passive transfer was ≥5.1 g/dL, yielding a sensitivity of 84% and a specificity of 90%. The semiquantitative antibody test on whole blood performed poorly, with a sensitivity of 77% and a specificity of 44%. This study demonstrates that serum total protein is a reliable measure for evaluating passive transfer of immunity and can be used despite a high prevalence of dehydration.

Hot topic: Accuracy of refractometry as an indirect method to measure failed transfer of passive immunity in dairy calves fed colostrum replacer and maternal colostrum

“…When using RID, FTPI is considered as serum IgG concentrations <10 mg/mL at 24 h after birth (Shivley et al, 2018); it has been previously defined by Besser et al (1991) and Furman-Fratczak et al (2011). Despite been the reference standard test, this assay is time consuming, expensive, not applicable on-farm, requires laboratory procedures and gives results in approximately 24 h (Deelen et al, 2014;Renaud et al, 2018). Consequently, practical and simple indirect measures are often used to estimate levels of serum IgG or FTPI (Hernandez et al, 2016).…”

“…It has been reported that STP is highly correlated with serum IgG and, as such, is commonly used to classify FTPI (McBeath et al, 1971;Deelen et al, 2014;Renaud et al, 2018). A wide range of STP thresholds (4.0-8.0 g/dL; Buczinski et al, 2018) have been used to classify FTPI.…”

“…They reported that it has the potential to be a rapid on-farm test to detect FTPI (sensitivity = 0.82 and specificity = 0.65). However, Renaud et al (2018) evaluated the same test in calves arriving at a milk-fed veal facility and stated that this test poorly detected FTPI (sensitivity = 0.77; specificity = 0.44). Another on-farm test that has been evaluated is a commercial quick IgG test.…”

The effect of Cryptosporidium parvum, rotavirus, and coronavirus infection on the health and performance of male dairy calves

“…The STP values were visually determined, and results were recorded first on paper and then entered into a spreadsheet. A STP level of < 5.1 g/dL was used as the cutoff for determining the presence of failed transfer of passive immunity (FTPI; Renaud et al, 2018a). Calves were also weighed on arrival using a digital weigh scale (Tru-Test, Mineral Wells, TX) and were weighed again at 14, 49, 56, and 77 d after arrival to assess growth.…”

Short communication: Effects of different blood buffers administered in electrolyte solution to grain-fed veal calves experiencing diarrhea

“…Upon arrival to the facility, whole blood was collected, and serum was separated and placed on the measuring surface of the digital refractometer (MISCO PA202, MISCO, Solon, OH) to estimate serum total protein (STP). A STP of <5.1 g/dL was used as the threshold for determination of failure of passive transfer of immunity (FPT; Renaud et al, 2018). Calves were individually housed in 1-m 2 individual stalls for the milk feeding period.…”