Given current farming conditions and the scale of production, all of us poultry farmers attach great importance to vaccinating our flocks. However, in production practice, we have found that when different farmers use the same immunization program or the same vaccines, the flocks can show different immune responses after vaccination. Clinical investigations have revealed many gaps in immunization practices. The findings are summarized below:
I. The immunization program is not formulated with reference to disease prevalence in the local area and at the farm.
Formulating an immunization program is one of the most important measures for guiding a farm’s immunization work. There are many immunization programs available on the market for reference, but they may not necessarily suit a particular farm. Therefore, when formulating an immunization program, we must consider not only disease prevalence in the local area but also disease prevalence at the farm, the chickens’ physiological patterns, and the pattern of antibody decline.
II. The vaccine strain selected does not match the circulating disease strain.
There are many types of vaccine strains. When selecting a vaccine, first determine the local strain type, serotype, or subtype. The vaccine can provide protection only when its strain type, serotype, or subtype matches the strains circulating in the market; otherwise, it will provide no protection.
III. Correct immunization procedures are not followed.
Improper immunization practices can affect the flock’s immune response. Different vaccines require different immunization methods. For example, inactivated vaccines are commonly administered by subcutaneous injection in the neck or by intramuscular injection; fowlpox vaccine is commonly administered by wing-web stab inoculation; and Newcastle disease freeze-dried vaccine is commonly administered via drinking water, spray, eye drops, or nasal drops. Therefore, only by selecting the correct immunization and administration methods can the desired results be achieved.
Four, the timing of flock immunization is incorrect.
To achieve the desired immunization results, the following situations must be considered: First, whether the flock is healthy. When notifying farmers of antibody test results, we ask about the flock’s health whenever booster vaccination is needed. If the flock is unhealthy, wait until it is healthy before vaccinating. Second, consider whether there is any interference between the vaccines being administered. Finally, avoid stressing the flock for 3 days before and after immunization. Stress can reduce the flock’s immune response and easily lead to immunization failure. Therefore, anti-stress medication should be added to the flock’s feed for three days before and after immunization.
Five, the vaccine dosage is inaccurate.
Some farmers are in the habit of increasing the vaccine dosage during immunization, especially when using Newcastle disease freeze-dried vaccine. They believe that a higher dose produces better results, but this is not scientifically sound. A vaccine dose that is too low or too high will not achieve the desired immunization results. An insufficient dose may fail to stimulate the body to produce effective antibodies, or the antibodies produced may not last long. An excessive dose may cause immune paralysis or toxic side effects in the flock.
Six, some birds in the flock are missed during vaccination.
When vaccinating their flocks, farmers often invite vaccination teams to help. However, antibody test results from the past two years have shown that missed vaccinations are becoming increasingly common, especially on large-scale farms. Birds that miss vaccination have weaker resistance and are more prone to illness, which can leave the entire flock in a subhealthy state. Therefore, missed vaccinations must be prevented whenever a flock is vaccinated, regardless of the vaccine.