When resistance level stays above the disease challenge, animals stay healthy Figure 2.
Vaccines raise the resistance level.
To properly immunize cattle against diseases, you must recall how each of the vaccines is formulated, what is the route of administration, how does the body respond to the vaccine in the presence or absence of maternal antibodies, and how many doses are required to stimulate the body to produce adequate levels of resistance against a particular disease. There are four vaccine forms. Usually only one dose of replicating vaccine will stimulate high levels of long-lasting resistance in an animal. Failure of the vaccine organism to replicate will mean failure to stimulate a rise in the animal's resistance. Examples of replicating - ML vaccines are listed.