Abstract
Simple SummaryCalves are born agammaglobulinemic and they rely on transfer of passive immunity (TPI) through ingestion of colostrum from the dam. Ensuring the effectiveness of TPI through blood serum immunoglobulins (IgG) quantification is of critical importance for the prevention of calf diseases. Therefore, this study primarily examined the performance of a novel on-farm quick test (SmartStripsTM, Bio-X Diagnostics, Rochefort, Belgium) to directly measure serum IgG concentration and assess TPI status in beef and dairy calves. Results showed that the quick test would provide veterinary practitioners and producers with an appropriate on-farm tool for direct calf serum IgG measurement and the assessment of TPI status. Such a tool would allow them, for instance, to take early actions regarding colostrum feeding practices or cow nutrition in the dry period to improve TPI and reduce calf morbidity, investigate calf health problems, or predict and measure the risk for pathology and antibiotic treatments in calves.Calves are born agammaglobulinemic and they rely on transfer of passive immunity (TPI) through ingestion of colostrum from the dam. Ensuring the effectiveness of TPI through blood serum immunoglobulins (IgG) quantification is of critical importance for the prevention of calf diseases. The main objective of this study was to assess the performance of a novel on-farm immunochromatographic quick assay (SmartStripsTM, Bio-X Diagnostics, Rochefort, Belgium) compared to the ELISA reference method to directly measure serum IgG concentration and assess TPI status in beef and dairy calves. Additional comparison was made with the commonly used Brix refractometer. Jugular blood samples were collected from beef (n = 71) and dairy (n = 26) calves in Belgium within 7 days post-birth. Quantitative (Pearson correlation coefficients, Bland-Altman plots) and qualitative (diagnostic test characteristics, weighted kappa for classification into 4 categories of TPI) analyses were performed to evaluate the performances of the quick test and the refractometer compared to ELISA. The quick test showed a correlation of 0.83 and a classification agreement (weighted kappa) of 0.79 with the reference method (average values for two types of blood anticoagulants). Performances were better for low IgG concentrations and the assessment of poor TPI status and they outperformed those of the Brix refractometer. Results suggested that the immunochromatographic quick test can be considered as a suitable on-farm method for direct serum IgG measurement and the assessment of TPI status in calves, contributing to timely interventions in the management of calves with inadequate TPI.
Highlights
Calves are born agammaglobulinemic as the structure of the bovine placenta prevents the transfer of immunoglobulins (Ig) from the dam to the fetus [1]
Mean immunoglobulin G (IgG) concentration measured by enzyme-linked immunosorbent assay (ELISA) was 13.6 (SD = 7.5), with a range from 1.3 to 37.1 mg/mL
Mean IgG concentration measured by the quick test was 12.8 and 12.0 (SD = 5.7 and 5.3) for ethylenediamine tetraacetic acid (EDTA) and lithium heparin anticoagulants, respectively
Summary
Calves are born agammaglobulinemic as the structure of the bovine placenta prevents the transfer of immunoglobulins (Ig) from the dam to the fetus [1]. Immunoglobulins are absorbed into the calf’s blood through the intestine and this absorption ceases approximately 24 h after birth due to the rapid modification of the gut enterocytes, meaning that early administration of colostrum is essential [3] This transfer of Ig from the dam colostrum to the offspring is referred to as “passive transfer of immunity” or “transfer of passive immunity” (TPI) [4]. Immunochromatography is a technique in which immunochemical reactions are carried out on a chromatographic paper by capillary action [30] This novel semi-quantitative test provides a value of the IgG concentration in calf blood serum within 15 min. The main objective of this study was to assess the performance of the immunochromatographic quick test compared to the ELISA reference method to quantify serum IgG concentration and assess the TPI status in dairy and beef calves. Secondary objectives were: (1) a comparison with the commonly used digital Brix refractometer, and (2) the evaluation of the effect of the anticoagulant type (ethylene-diamine-tetra-acetic acid (EDTA) vs. lithium heparin, which are common anticoagulants) in the blood sampling tubes on the performances of the quick test
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