ANTIBODY DETECTION IN MATCHED CHICKEN SERA AND EGG-YOLK SAMPLES BY COMMERCIAL ENZYME-LINKED-IMMUNOSORBENT-ASSAY KITS FOR NEWCASTLE-DISEASE VIRUS, INFECTIOUS-BRONCHITIS VIRUS, INFECTIOUS BURSAL DISEASE VIRUS, AND AVIAN REOVIRUS

ELISA kits have been used to detect antibody in egg yolk. The major ad vantage eggs offer over blood samples is the ability to collect sample s without compromising flock biosecurity. A disadvantage to using egg yolk over sera concerns the method of preparing yolk for antibody test ing. The technique used in this study involved a simple dilution metho d with no mixing or extraction. To determine the adequacy of yolk samp les to replace serum samples, a serum sample and the first six eggs we re obtained from each of 50 commercial leghorn hens. Mean titers were consistently larger for serum than for yolk, but the size of the diffe rence varied with the virus. The variation of mean egg titer was compa rable to that of the serum titer. Correlations between a hen's serum t iter and the mean titer from hen eggs were only moderate, ranging from 0.35 to 0.85 across viruses and systems. The ability to predict the s erum titer of a single hen by the mean titer from hen eggs may be inad equate.