Correlation of haemagglutination inhibition and enzyme‐linked immunosorbent assays for antibodies to Newcastle disease virus

Abstract

Antibody responses of commercial broiler chickens vaccinated for Newcastle disease were assayed by haemagglutination inhibition and enzyme‐linked immunosorbent assay, and the results from the two methods compared. Three‐hundred‐and‐nineteen chickens from 37 farms were assayed. The correlation coefficient was 0.85. Analysis of individual slopes of data from the 37 farms indicated that at least eight chickens from a farm must be sampled to achieve an acceptable degree of parallelism.