A Cross-sectional Study for Mycoplasma Gallisepticum Antibodies in Non-vaccinated Commercial Layer Birds in Khulna District

A cross-sectional study was carried out on 96 commercial layer farms of six upazilas of Khulna district to know the seroprevalence of Mycoplasma gallisepticum (MG) infection during the period from August 2009 to July 2010. A total of 1268 sera samples were collected from randomly selected layer birds of different age groups and tested by serum plate agglutination (SPA) test by using commercial MG antigen (Nobilis MG, Intervet International) to detect the presence of antibodies against MG. The overall prevalence of MG infection was recorded as 67.4%. Age-wise analysis revealed that there was significant relationship (p<0.001) between MG infection and age of birds. The highest prevalence of MG infection was 71.2% in 21-56 weeks age group followed by 66.8% in 8-20 weeks age group. There was significant (p<0.001) variation in the seroprevalence in terms of areas of study (upazilas). Significant (p<0.001) effect of seasons in the seroprevalence of MG infection in layer birds was observed in the present study. The prevalence of MG infection was the highest (75.6%) in winter season followed by summer (66.3%) and rainy (60.8%) seasons. The seroprevalence of MG infection was higher in most of the large flocks and lower in small flocks with some exceptions. It is evident from the present study that above 50% layer birds are infected with MG organism. Therefore, it may be suggested that the layer farms should be routinely checked to monitor MG infection and the reactor birds should be culled since MG organism has the potential to transmit vertically.