title: Comparison of rapid laboratory tests for failure of passive transfer in the bovine.
abstract: BACKGROUND
  Failure of passive transfer of maternal immunity via colostrum can occur in the bovine, and a number of blood tests have been developed to test calves for this failure. It is not clear which test is most suitable for this purpose. The objective was to examine the most commonly used tests for failure of passive transfer and to decide which is most suitable for routine laboratory use. 126 serum samples were taken from calves of dairy cows after birth but prior to colostrum feeding, and at 48 h of age. Five different tests were compared against radial immunodiffusion which is considered the appropriate reference method. These tests were serum gamma-glutamyltransferase levels, serum protein levels, serum globulin levels, an enzyme linked immunosorbent assay and the zinc sulphate turbidity test.
  
  
  RESULTS
  The tests examined displayed high sensitivity but widely varying specificity. Examination of the use of different cut-off points allowed some improvement in specificity at the expense of sensitivity, but the tests which had performed best at the original cut-off points still displayed the best performance. Gamma-glutamyltransferase levels as a measure of colostrum absorption returned, in this study, the best balance between sensitivity and specificity. The ELISA used in this study and serum globulin levels displayed performance similar to the gamma-glutamyltransferase levels. Serum total protein was less successful than others examined at providing both sensitivity and specificity but may, when performed via refractometer, be useful for on-farm testing. As currently performed the poor sensitivity for which the zinc sulphate turbidity test is most often criticized is evident. Modification of the cut-off point to increase specificity is less successful at balancing these parameters than the ELISA, gamma-glutamyltransferase levels, and globulin levels.
  
  
  CONCLUSIONS
  Gamma-glutamyltransferase levels, ELISA testing and circulating globulin levels performed best in detecting failure of passive transfer in serum samples, although all three had some practical considerations.
authors: Department of Agriculture Food and the Marine, Regional Veterinary Laboratory, Knockalisheen, Limerick, Ireland.
authors: Ian
authors: I
authors: Hogan
authors: Veterinary Clinical Studies, School of Veterinary Medicine, UCD, Belfield, Dublin 4 Ireland.
authors: Michael
authors: M
authors: Doherty
authors: Regional Veterinary Laboratory, Coosan, Athlone, CO. Westmeath Ireland.
authors: John
authors: J
authors: Fagan
authors: Animal & Grassland Research and Innovation Centre, Teagasc, Moorepark, Fermoy, Co Cork Ireland.
authors: Emer
authors: E
authors: Kennedy
authors: Animal & Grassland Research and Innovation Centre, Teagasc, Moorepark, Fermoy, Co Cork Ireland.
authors: Muireann
authors: M
authors: Conneely
authors: Department of Agriculture Food and the Marine, Regional Veterinary Laboratory, Knockalisheen, Limerick, Ireland.
authors: Paula
authors: P
authors: Brady
authors: Department of Agriculture Food and the Marine, Regional Veterinary Laboratory, Knockalisheen, Limerick, Ireland.
authors: Clare
authors: C
authors: Ryan
authors: Herd Health and Animal Husbandry, UCD School of Veterinary Medicine, Belfield, Dublin 4 Ireland.
authors: Ingrid
authors: I
authors: Lorenz
keywords: Calves; Disadvantages in practicality; Failure of passive transfer; Laboratory tests