Comparison of haemagglutinins and haemagglutination inhibition titres between Lasota and Komarov strains of Newcastle disease virus

The chronic and major problem of drop in egg production in layers due to low immunity to Newcastle disease virus (NDV) has been reviewed beyond the purview of breakdown of immunity. Ambiguity between flock average of haemagglutination inhibition (HI) titre and actual egg production with respect to LaSota vaccination, especially during lay period, is presented. The flock with HI titre as high as 280.6 following LaSota vaccination, had shown upto 10%drop in egg production. On the other hand, ‘K’ vaccination maintained the egg production at 87% with flock average HI titre of 98. Preference of LaSota by most farmers for reasons such as easy administration, availability from all manufacturers and availability in combination with infectious bronchitis vaccine virus etc. can not compensate this 10% egg loss.