Serological study of agents associated to chronic respiratory syndrome in laying hens
Abstract
In order to evaluate the serological response to agents associated to chronic respiratory syndrome in poultry, 120 White Leghorn replacement layers, having received all the vaccines of the immunization program currently applied in Cuba, were selected and sampled monthly from the 12th to the 50th week of age. The samples were assayed for antibodies against Mycoplasma gallisepticum (by fast serum plate agglutination), Ornithobacterium rhinotracheale and Avian Infectious Bronchitis Virus (by ELISA), and Newcastle Disease Virus (by hemagglutination inhibition assay, HIA); comparing the proportion of birds positive to Mycoplasma gallisepticum, Ornithobacterium rhinotracheale, or with HIA titers higher than 1/8, and performing an analysis of variance for the geometric means of the antibody titers against the Avian Infectious Bronchitis Virus at p < 0.05 for statistical significance, as implemented in the Comprop-1 and Statgraphics Plus 5.1 statistical software packages. The results corroborated the presence of M. gallisepticum and provided the first evidence of positive reactions to O. rhinotracheale in laying hens with chronic respiratory syndrome. The serological kinetics of the bird population vaccinated against avian infectious bronchitis evidenced a second seroconversion event, probably due to the circulation of this infectious agent. No serological responses against Newcastle Disease Virus were detected. Further studies for the isolation and characterization of different O. rhinotracheale serovars from laying hens with chronic respiratory syndrome are required.
