Loss of cell-associated Marek's disease vaccine titer during thawing, reconstitution, and use.

Tests of the effects of mismanagement practices observed in hatcheries showed that very subtle deviations from the explicit directions accompanying Marek's vaccine can cause dramatic losses of vaccine potency. Such mismanagement was found to result in 14 to 97% loss of vaccine titer. It appears that procedures used in hatcheries for the handling of cell-associated Marek's vaccine should be closely monitored on a continuous basis to prevent a gradual drift from correct handling.