Vaccination with CDF-66 strain of newcastle disease virus

Newcastle disease vaccine CDF-66 has been proved effective by the drinking water route. A chicken dose of 10(6.2) EID50 in 12 ml of water containing 2.5% skimmed milk was found to be effective. This produced sufficient GMHI antibody response (105) and 86.6% of birds withstood challenge with the Mukteswar strain of virulent virus. The in-contact birds did not show either immune or antibody response. The vaccinated birds excreted vaccine virus only from the respiratory tract not from cloaca. The vaccine given in drinking water protected only 50% of chickens when it was given 168 h prior to challenge virus. With lesser intervals the protection was negligible. Diluted vaccine when held for 2 h at 37 degrees C and room temperature did not show a drop in potency.