Comparison of Newcastle disease vaccine administered as powder or liquid in relation to the serum antibody response and adverse vaccinal reactions in broilers

Liquid spray and aerosol mass vaccination of poultry have several drawbacks, such as uncontrolled deposition of vaccine particles in the respiratory tract and vaccine virus inactivation by formation and evaporation of droplets. These may be addressed by using dry powder vaccines with defined particle size distribution targeting the upper (primary vaccination) or the entire respiratory tract (booster vaccination). Therefore, a coarse Newcastle disease (LZ58 strain) powder vaccine was administered to specified pathogen free (SPF) broiler hens to compare the antibody response and adverse vaccinal reactions with those induced by a coarse liquid spray and a fine liquid aerosol. Groups of 40 broilers each housed in isolators were vaccinated at 4 days of age and intratracheally inoculated with Escherichia coli (strain 506) at 11 days of age. Adverse vaccinal reactions were evaluated by measuring body weight gain and mortality between 4 and 11 days of age and between 11 and 18 days of age, and by recording colibacillosis lesions at 18 days of age. The antibody serum response was measured at 18 days of age by the haemagglutination inhibition test. Despite the relative low initial vaccine virus loss and narrow particle size distribution of the powder vaccines in comparison with their liquid counter parts, no significant differences (P > 0.05) regarding adverse vaccinal reactions and antibody response were observed between broilers vaccinated with the powder vaccines or with their liquid counterparts.