When a chicken is vaccinated or exposed to a disease, it responds by producing antibodies against that specific disease organism. Antibodies are proteins responsible for fighting bacteria, virus and other foreign substances that enters the body. What serological monitoring does is to extract serum from chicken blood and estimate the quantity of antibodies present in it. Serological monitoring has 4 benefits:

1. It helps you to know the right age to vaccinate. You’ll be able to develop a solid vaccination plan rather than guessing.
2. It helps you to evaluate and improve vaccination programs. It helps you to determine the effectiveness of past vaccinations
3. It helps you to monitor the flock for various diseases and you’ll be able to detect impending diseases.
4. It helps you to rapidly detect diseases

Personal Experience:

I once took 10 out of my 607 chicks to a lab (AnimalCare Asaba) for serological test. The result showed that the chicks have very low immunity against Newcastle and gumboro diseases. This means that if I had followed the ‘normal’ vaccination plan that says that you give gumboro vaccine on day 10, a lot of my chicks might have died due to gumboro disease (this is a very deadly disease to chicks). So rather than vaccinating on day 10, I had to vaccinate on day 5 (due to some reasons, I actually vaccinated on day 6). This was followed by Immucox (coccidiosis vaccine) the next day and then lasota (Newcastle disease vaccine). So that was how serological test saved me from impending danger. If you have large number of birds, going for day old chick screening is worth the cost.

Serological monitoring helps you to design a good vaccination plan and to know how well past vaccinations have performed. The common practice among most farmers is to follow a sample vaccination plan and treat diseases as they arise. While this method can work some times, it is not the best because you miss the 3 benefits listed above. Serological monitoring forecast the future and enables you to take the appropriate action before problems crop up.

Determining the Right Age to Vaccinate

When chicks hatch, they can resist some diseases because they inherited some antibodies from the hen through the egg. These inherited antibodies are called maternal antibodies. The maternal antibody will not provide permanent immunity to the chicks because it will eventually disappear as the chicks grow.

The level of maternal antibodies in the chicks’ blood is a very important factor to consider during vaccination. If you vaccinate against a disease when the level of maternal antibody against that disease is high, the vaccination will fail and the chicks will not be protected. So when the maternal antibody finally declines, the chicks will become infected if exposed to the disease – despite the fact that you have vaccinated them in the past.

To prevent vaccination failure due to level of maternal antibodies, you need to conduct serological test. This is usually done within the first week of the chicks’ life and it will determine the quantity of maternal antibodies the chicks received and predict the rate at which it will decline. This will help you determine the correct time to vaccinate.

So with serological monitoring, you’ll know when the maternal antibodies have decline and that is the right time to vaccinate.

Note: To get vaccination plan through serological test, you just need to do the test once.

Evaluating and Improving Vaccination Plan

Serological testing helps you to evaluate and improve your vaccination plan. It is used to measure concentration of antibodies before vaccination and 3-4 weeks after vaccination. If the concentration of antibodies is uniform and is increasing, it then means that the vaccination was effective and vice versa. This knowledge will then help you to improve your vaccination plan regarding vaccine strains, day of vaccination, adding a booster, changes in vaccine administration methodology etc. However, this is suitable only for large farms due to the cost.

Monitoring the Flock for Various Diseases

Every 5-6 weeks, serological monitoring can be done to determine the antibody titers and immune status of flocks against important diseases like Newcastle, Infectious bronchitis, gumboro, egg drop syndrome, avian influenza, chicken infectious anemia, mycoplasma, pasteurella and salmonella – suitable for large farms. This test will help you to know when diseases are creeping in and enable you to take action before they strikes.

Serology results must be interpreted in association with other sources of information like vaccination history, production data, condemnation data, clinical signs and necropsy findings. Also, titers (concentration of antibodies in blood serum) due to field exposure (exposure to the real disease-causing agents) should not be confused with vaccine-induced titers. Analyzing data carefully based on vaccination history can help differentiate between the two.

Note: Both vaccine and exposure to diseases can increase the concentration of antibodies in the blood.

Detecting Diseases

Serological test is the most rapid and economical method for detecting diseases like chicken infectious anemia, reovirus infections, avian encephalomyelitis, Avian leukosis complex, reticuloendotheliosis. Other diagnostic procedures like virus isolation, histopathology and molecular biological examinations are less economical to perform and take time.

Conclusion

Serological monitoring has a lot of benefits that can save you from disaster. It helps you to know the right time to vaccinate your birds. It also helps you to determine if past vaccinations were effective and it warns you of impending diseases.