Evaluation of different analytical methods to assessfailure of passive transfer in neonatal calves

摘要

The objective of this study was to evaluate differentanalytical methods of assessing failure of passive transfer(FPT) in neonatal calves. We hypothesized that3 different media (i.e., centrifuged serum, centrifugedplasma, filtered plasma) and different analytical methods[i.e., ELISA, capillary electrophoresis (CE), Brix refractometer,and handheld optical refractometer] wouldbe highly correlated with the gold standard radial immunodiffusion(RID) and would generate comparableresults. Serum and plasma blood samples were collectedfrom Holstein Friesian calves (n = 216) aged 1 to 7 d,from 2 commercial dairy herds in northeast Germany.The RID analysis showed that 59 of 216 calves (27%)had serum IgG concentrations of <10 mg/mL and 157calves (73%) had serum concentrations of ≥10 mg/mL.The mean IgG concentration (± standard deviation)was 17.1 ± 9.8 mg/mL, and the range was 0.8 to 47.8mg/mL. In serum, the correlation between RID and CEwas r = 0.97, and between RID and ELISA was r = 0.90;CE and ELISA were also highly correlated (r = 0.89).Both refractometry methods were highly correlatedwith RID using centrifuged serum, centrifuged plasma,or filtered plasma (Brix refractometer: r = 0.84, 0.80,and 0.78, respectively; handheld optical refractometer:r = 0.83, 0.81, and 0.80, respectively). We determinedtest characteristics (optimum thresholds, sensitivity,specificity, positive predictive value, negative predictivevalue, and area under the curve) for CE, ELISA, andthe handheld optical and digital refractometers usingreceiver operating characteristic curve analyses withRID as the reference value. Optimal thresholds for assessingFPT using plasma were higher than for serum,regardless of the method of plasma harvesting. The 4different devices had comparable areas under the curve,irrespective of the medium used. All analytical methodscan be used to assess FPT.