When is the best time to inject the Newcastle disease and influenza dual killed vaccine?

When is the best time to inject the Newcastle disease and influenza dual killed vaccine?

The best time to inject the H9N2 killed vaccine (in dual or triple vaccines) should be determined based on the maternal antibody (MDA) level so that it is neither too early (so that the MDA will inhibit the immune response) nor too late (so that the bird is left unprotected).

The best time is when the HI titer of the chicks is less than 4.

The best time, according to the above article, to inject this vaccine is on the 6th - 8th day of age for the following reasons:

1. On the one hand, the maternal antibody titer will decrease and its inhibitory effect will be less.

2. On the other hand, it will take at least 14 days after injection for neutralizing antibodies to form and prevent the virus from circulating and contaminating the farm.