The Primary Reasons for Success and Failure of Poultry Vaccination

Understanding Poultry Vaccines: The Difference Between Live and Killed Vaccines

Before delving into the reasons for vaccine failures, it’s essential to understand the different types of vaccines. Vaccines are generally categorized into two types:

• Live Vaccines: Live poultry vaccines contain a virus or bacteria that must infect the bird and replicate within its body to induce immunity, preferably with minimal side effects. As the virus multiplies in the bird’s body, the immune system recognizes the virus, leading to a robust immune response.
  • Advantages of live vaccines: These include ease of administration, low cost, rapid onset of immunity, and a broader spectrum of protection as the birds are exposed to all stages of viral replication.
  • Disadvantages of live vaccines: Challenges include inconsistent vaccine application, higher rates of adverse reactions, the potential for unintended spread of the vaccine virus to neighboring farms (if they are not vaccinated), and the need for strict storage conditions to maintain the viability of the vaccine organism.
• Killed Vaccines: Killed poultry vaccines are made from bacteria or viruses that have been inactivated and processed, making them unable to spread from one bird to another. Killed vaccines are usually combined with an adjuvant such as aluminum hydroxide or oil. Adjuvants enhance the immune response by increasing the vaccine’s stability in the body and stimulating a longer-lasting immune response. Killed vaccines can only be administered via injection.
  • Advantages of killed vaccines: These include ensuring a uniform dose (birds are injected individually), safety (the organism is inactivated), development of uniform levels of immunity (each bird receives the same dose), no chance1 of the vaccine organism spreading to neighboring poultry farms, increased product stability, and the ability to select a wider range of viral strains.
  • Disadvantages of killed vaccines: These include increased costs (labor and product), slower onset of immunity, a narrower spectrum of protection, and the possibility of local tissue damage at the injection site due to the adjuvant reaction.

Types of Vaccination Methods: The Best Way to Inject Vaccines into Chickens

There are various methods for administering vaccines to poultry, each with its own advantages and disadvantages. Vaccination methods can be categorized into two main types: injectable and non-injectable.

• Injectable Poultry Vaccination: In this method, the vaccine is injected into the bird or egg. When using the injection method, it’s crucial to avoid damaging the bird’s tissues. The vaccine needle should be inserted and withdrawn directly from a small point. Shaking and movement of the vaccine within the bird’s tissues can cause damage and bleeding. There are three main types of injection methods:
  • Subcutaneous Poultry Vaccination: In this method, the vaccine is injected directly under the skin, usually in the neck or shoulder area. This method is suitable for small chicks.
  • Intramuscular Poultry Vaccination: In this method, the vaccine is injected into the muscle, usually in the breast area. This method is suitable for larger birds once the breast muscle has developed. Care must be taken during vaccination to avoid injecting the needle into the bird’s heart. Typically, the vaccine is injected into the right breast of the bird.
  • Egg Injection: This method is performed in the early stages of embryonic development and requires specialized equipment.

• Non-Injectable Poultry Vaccination: In these methods, the vaccine is administered to the birds through drinking water, eye drops, or spray.
  • Poultry Spray Vaccination: In this method, the bird receives the vaccine through the eyes, nose, and mouth. The temperature of the water used to dilute the vaccine should be between 12 and 18 degrees Celsius. The size of the vaccine particles after spraying is very important. Particles should not be too fine or too coarse. For spray حoultry vaccination, be sure to use devices specifically designed for this purpose. The holes in these devices are designed to produce vaccine particles of the appropriate size. If the vaccine particles are too fine (less than 50 microns), they may enter the deep respiratory tract of the bird and cause disease. On the other hand, if the vaccine particles are too coarse (more than 200 microns), they will quickly settle to the ground due to their weight and the bird will not be able to receive them. Note that the ambient temperature during spraying should be neither too high nor too low.
    • Environmental conditions: The ambient temperature during spraying should be between 26 and 27 degrees Celsius. During this time, the ventilation and heater should be turned off to prevent air movement and dispersion of vaccine particles. In the spray vaccination method, in addition to direct absorption of the vaccine through the bird’s eyes, nose, and mouth, indirect absorption is also possible. When birds come into close contact with each other after spraying, the vaccine that has settled on their bodies may be transmitted through direct contact with the eyes or nose of another bird or through fine vaccine particles that are dispersed in the air and inhaled and absorbed by the bird. For this reason, it is recommended that the ventilation and heater be kept off for 5 to 7 minutes after spraying to allow sufficient time for the vaccine to be absorbed.
  • Eye Drop Vaccination for Poultry: One of the effective methods for vaccinating poultry is the eye drop method. In this method, the vaccine is administered directly into the bird’s eye as a drop. This method is particularly common for vaccines against diseases such as infectious bronchitis.
    • Procedure: In this method, the specialist gently holds the bird and keeps its head steady. Using the thumb or index finger, the lower eyelid of the bird is gently pulled downwards to expose the conjunctival sac. Finally, a specific amount of vaccine is gently dropped into the bird’s eye. The tip of the dropper should not come into contact with the bird’s eye. The exact amount of vaccine required for each bird is usually indicated on the vaccine vial. For example, for every thousand broilers, depending on the age of the bird, between 35 and 50 milliliters of vaccine is used.
  • Poultry Drinking Water Vaccine: Drinking water vaccination is one of the most common vaccination methods in poultry. In this method, the vaccine is added to the birds’ drinking water, and they are vaccinated by drinking the water. This method is very popular due to its simplicity, speed, and low cost. However, to ensure the success of vaccination, it is essential to pay attention to factors such as water quality, temperature, and the contact time of birds with the vaccinated water. Additionally, the type of vaccine and the manufacturer’s instructions must be carefully followed. Due to the many details involved in this method, we have discussed it in detail in a separate article.

Article: Poultry Drinking Water Vaccination

The type of vaccine and the method of administration depend on many parameters, including species, size, health status, inherent immunity, production cycle length, selected protocol, cost, and more. However, the common point of all vaccines is that their efficacy is highly dependent on proper storage, handling, and management methods. Unfortunately, improper use during vaccine administration is very common, usually due to human error and is considered one of the main reasons for vaccine failure.

Risk Factors for Vaccination Failure: Why Vaccination Doesn’t Always Work

Poultry vaccination is highly effective in preventing and controlling infectious and viral diseases in poultry. For vaccination to be effective, it requires the use of a quality vaccine and a proper vaccination method in the flock. Vaccination failure in a poultry farm occurs when, after the vaccine is administered, the birds’ bodies do not produce sufficient levels of antibodies or remain susceptible to disease outbreaks in the poultry house.
Usually, when vaccination fails, there is a tendency to blame the vaccine. While this is certainly an important consideration, other factors can also lead to the failure of flock vaccination.
Several factors can cause the immunization of vaccinated poultry to fail. Although the vaccine can increase an animal’s resistance to disease, this resistance is lost if management practices are not carried out correctly. Poor hygiene along with stressors, overcrowding, concurrent infection, and contaminated water reduce the effectiveness of the vaccine in poultry.
All of these factors are equally important. Failure to comply with any of these factors jeopardizes the overall quality of vaccination. These factors include exposure to high levels of infectious agents, poor quality vaccines, antigenic differences between the existing vaccine and circulating strains in the geographic area, vaccination strategy, improper use, and a shortage of skilled veterinary technicians to administer the vaccine.
In general, problems related to poultry vaccines include:

• Vaccine inactivation
• Ignoring the vaccine antigen with the field strain
• Incorrect timing of vaccine injection
• Stressors and immunosuppressive diseases
• Failure to follow the vaccine manufacturer’s instructions

Improper Storage and Instability of the Vaccine in the Cold Chain

The effectiveness of a vaccine is linked to the potency of the vaccine’s agents (viruses and bacteria) and their replication in poultry. Several factors can inactivate a vaccine. Therefore, vaccine inactivation and the failure of poultry vaccination can be attributed to factors such as:

• Vaccine Inactivation Due to Expiration Date: The potency of vaccines remains for a specific period. Therefore, even if stored at the appropriate temperature, after the expiration date, its effectiveness is lost.
• Contamination of Injection Equipment: If there is any contamination on the vaccine, not only will the vaccination be useless, but it may also make the flock susceptible to disease due to the presence of contamination. The presence of detergents and disinfectants on the equipment may also inactivate the vaccine. The presence of any contamination or disinfectants and detergents on the vaccination tools endangers the vaccination.
• Vaccine Inactivation Due to Improper Storage: Failure to store the vaccine at the appropriate temperature causes the vaccine to become inactive. Throughout the entire vaccination process, from purchase to injection, vaccines must be stored, transported, and used correctly according to the manufacturer’s recommendations. Common storage problems that lead to vaccine inactivation include:
  • Lack of Storage Equipment: Lack of efficient and effective refrigerators damages the vaccine.
  • Failure to Adhere to the Cold Chain and Proper Storage Temperature: If the appropriate cold temperature is not maintained during the vaccine transportation process, it leads to the denaturation of the vaccine. Denaturation of vaccines means that the proteins and other components of the vaccine lose their original structure. As a result, they lose their ability to stimulate the immune system. Typically, the storage temperature of poultry vaccines should be between 4 and 8 degrees Celsius. However, it is emphasized that you should follow the manufacturer’s storage protocol.
  • Exposure to Sunlight: Antigens are killed when the vaccine is exposed to direct sunlight. This leads to a decrease in antigen concentration and vaccine effectiveness.
  • o Mixing the Vaccine with Other Foodstuffs: The food refrigerator should be separate from the vaccine refrigerator. Any contamination contaminates the vaccine space. The presence of chicken or eggs is particularly harmful in this regard. Even if the vaccines are sealed, avoid placing them in the food refrigerator. Keep in mind that contamination will still be on the vaccine containers themselves, and you will be introducing it into the breeding environment.

Neglecting Genetic Factors in Poultry Vaccination

A bird’s response to a vaccine depends on its species. A specific part of a bird’s genes, called the Major Histocompatibility Complex (MHC), plays a crucial role in the immune system. This part determines how a bird’s body reacts to bacteria and viruses. In essence, the MHC is a portion of an organism’s genome that plays a vital role in the immune system. This gene region produces proteins that help immune cells distinguish between self-cells and foreign cells (such as bacteria and viruses). Some birds may be more susceptible to disease due to differences in this genetic structure. Therefore, understanding the common diseases in a specific bird species is crucial.
On the other hand, disregarding the vaccine antigen and the field strain renders vaccination ineffective. Before diving deeper into the text, let’s understand what an antigen is. An antigen is a part of a microbe (like a bacterium or virus) that stimulates the immune system to produce antibodies. Antibodies act like keys that bind to specific locks (antigens) on microbes, marking them for destruction.
Now, if microbes gradually make small changes in their antigens (known as antigenic drift), it causes the antibodies produced by the vaccine to function poorly. Sometimes, these changes in antigens are significant (known as antigenic shift), causing the vaccine to provide almost no protection against the new strain.
Therefore, understanding the disease strain and using the appropriate vaccine for injection is crucial for vaccination effectiveness. In fact, effective antibody-mediated immunity is established when antibodies bind precisely to the specific antigenic strain on the surface of the bacterium or virus. Changes in microbial antigens can reduce the effectiveness of vaccines. These changes are more commonly observed in killed vaccines. For a vaccine to work well, the antigens (parts of the virus that stimulate the immune system) present in the vaccine must resemble those of the actual virus.
To address this issue, scientists continuously monitor new strains of microbes and update vaccines as needed.

Inappropriately Timed Poultry Vaccination

To ensure maximum effectiveness of vaccines in poultry, they must be administered at the optimal time, considering the presence or absence of maternal antibodies. If the vaccination schedule is incorrect or if the maternal antibodies are too strong, the vaccine may not work as intended.
To determine the ideal vaccination time for a flock, the following factors should be considered:

• The role of maternal antibodies in vaccination failure: Mother hens are routinely vaccinated against various infectious diseases based on their prevalence. Chicks acquire maternal antibodies through the egg, which provide protection for the first two weeks of life. Research has shown that maternal immunity can safeguard chicks against infectious diseases like Newcastle disease and Gumboro during the first week. If chicks are vaccinated during this period, the presence of maternal antibodies can interfere with the vaccine antigens, potentially neutralizing them. The optimal time for vaccination is when the protective effects of maternal antibodies have waned. If vaccinated too early, maternal antibodies may neutralize the vaccine and hinder the development of an immune response.
• The Importance of Booster Doses: A booster dose of a vaccine is an additional dose of antigen administered to reinforce the immune response initiated by a primary dose. The primary goal of booster doses is to strengthen the body’s immune response and provide long-lasting protection against diseases. The initial dose stimulates the immune system to produce antibodies. When administered at the appropriate age, the primary dose helps the developing bird’s immune system become familiar with the vaccine antigen and generate a suitable immune response. The booster dose amplifies this response and extends the duration of immunity.

If poultry do not receive booster doses, the level of antibodies in their bodies may decrease below protective levels. A decrease in antibody levels signifies reduced vaccine efficacy, making the birds more susceptible to diseases. Consequently, unvaccinated birds are more likely to contract diseases and experience related complications. Therefore, to ensure a higher level of protection, it is recommended to administer booster doses according to the recommended schedule.

Furthermore, frequent vaccination of poultry may expose them to various diseases before their immune systems have fully activated. All aspects of vaccination, including vaccine selection and dosage, should be overseen by experts in the field.

• Failure Resulting from Simultaneous Administration of Multiple Vaccines: Studies have shown that when multiple vaccines are administered simultaneously, the antibody response to each vaccine can be reduced. Additionally, the combined administration of vaccines can increase the risk of morbidity and mortality. Therefore, it is recommended that vaccines be administered at different times and separately.

Vaccination Failure Due to Stress and Disease

Stress is a non-specific response to changes in the environment that exceed a bird’s physiological and behavioral coping capacity. Essentially, poultry under stress lack sufficient resources to defend themselves against diseases and environmental changes. Stressors in poultry include poor ventilation, cold, heat stress, excessive humidity, transportation, high flock density (crowding), limited space, poor hygiene, excessive litter, malnutrition and nutrient deficiencies, parasitic diseases, fever, and more.
All factors that induce stress in birds, from weather conditions to management problems, lead to a weakened immune response. Under such conditions, poultry become unresponsive to vaccination and are more susceptible to infections during disease outbreaks. Additionally, administering live vaccines to immunocompromised birds can potentially cause outbreaks within the flock.

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Immunosuppressive diseases are caused by a compromised immune response, increasing the risk of infectious diseases in flocks such as mycotoxicosis, infectious bursal disease (Gumboro), infectious anemia, Marek’s disease, and others. All of these conditions disrupt the immune response, which can lead to vaccination failure in poultry flocks. In fact, these conditions can overstimulate the immune system rather than strengthening it, causing a severe adverse reaction to the vaccine. This severe reaction can result in morbidity and even mortality.
The reason for this is the neutralization of vaccine antigens by antibodies naturally produced against infectious pathogens. This can worsen the disease condition in birds and even lead to mortality in the flock. Therefore, ensuring the health of birds before vaccination is highly recommended.
Additionally, after a correct vaccination, the bird’s body (host) needs a few days to develop an effective immune response. If an infectious agent is introduced before or during the vaccination period, the vaccine will be ineffective in producing sufficient antibodies, leading to vaccination failure.

Incorrect Vaccine Administration Routes in Poultry

Vaccines can be administered to poultry orally, subcutaneously, intramuscularly, in the wing, via drinking water, eye drops, or spray. If a vaccine is not administered using the appropriate vaccination site or recommended route, it may result in poor vaccine protection in poultry flocks. Among vaccination methods, injection and eye drop methods are considered the most effective. However, different methods are generally used in poultry farms depending on the circumstances.

Article: Frequently Asked Questions for Poultry Farmers

The Importance of Following Poultry Vaccine Manufacturer Instructions

Always adhere strictly to the vaccine manufacturer’s instructions. Avoid adding any extra substances during vaccine preparation. Some substances, such as disinfectants, contain components that can neutralize the vaccine’s effectiveness. During vaccine preparation, pay close attention to timing, duration of effectiveness, and the type of diluent.
The correct vaccine dosage is crucial. Using a lower concentration can result in inadequate vaccination of the flock, leading to disease outbreaks. Conversely, using an excessive dose can also have negative consequences. While vaccination is a vital disease prevention method, overdosing can lead to various complications:

• Immune suppression: High vaccine doses can overstimulate the bird’s immune system, compromising its ability to fight off other diseases. This can increase susceptibility to secondary infections.
• • Allergic reactions: Some birds may be allergic to vaccine components. Overdosing can exacerbate these allergic reactions, leading to symptoms like swelling, redness, and even anaphylactic shock.
• Growth impairment: Excessive vaccination can negatively impact bird growth and development, resulting in weight loss and reduced egg production.
• Disease development: In rare cases, vaccination with live attenuated viruses can cause disease. This risk is higher if the vaccine dose is excessive or if the bird’s immune system is weak.
• Increased costs: Overdosing increases production costs without necessarily improving performance.

Factors Affecting Vaccine Efficacy in Poultry: Achieving Vaccination Success

Addressing the challenges faced in poultry vaccination requires innovative solutions in vaccine development. To mitigate these issues, it is crucial to adhere strictly to the vaccine manufacturer’s guidelines. Additionally, the health of the flock and maternal antibody levels should be considered when administering vaccines. Therefore, poultry farmers and managers should consult with veterinarians before vaccinating and monitor the birds’ health prior to vaccination.
The objective of vaccination should be clearly defined, and the poultry farmer must implement all necessary measures to control both the methods used in vaccination operations and external factors. Moreover, vaccination contributes to enhanced disease control capacity in poultry and should be integrated with other disease control and eradication measures.
Key Factors Influencing Vaccination Success:

• Vaccine Quality: Always use vaccines from reputable brands. Poor vaccine quality (low titer, contamination, etc.) can compromise vaccination efficacy. Although the vaccine production industry is heavily regulated, vaccine-related failures are rare.
• • Vaccine Storage and Transportation: Proper vaccine storage requires adherence to the following critical points:
  • Store vaccines in a dedicated refrigerator at 2-8°C (35-46°F). Use a minimum/maximum thermometer to regularly monitor temperature.
  • Calculate the required doses to the nearest 1000.
  • Transport vaccines from storage to the vaccination site in a cool bag/styrofoam box, ensuring the temperature remains between 4-8°C (39-46°F).
• Avoid Using Expired Vaccines: Carefully check the expiration date on the vaccine container before use. Never use expired vaccines and dispose of them properly. The shelf life of vaccines varies depending on the type. For instance, live lyophilized vaccines have a longer shelf life (1-2 years) compared to oil-based vaccines (3-6 months).
• Cleaning Vaccination Equipment: All vaccination equipment must be clean. Wear gloves during vaccination and preparation. If you have cleaned syringes and equipment with disinfectants, rinse them thoroughly with warm water. Ensure that all disinfectants are completely removed. Never expose the vaccine to cleaning agents.
• Maternal Immunity Consideration: In most poultry farms, especially breeder flocks, vaccination is carried out through various methods and according to a schedule. As a result, day-old chicks have passive immunity in their blood due to maternally transferred antibodies. Therefore, especially for live vaccines, they are neutralized within the first two weeks if injected. According to scientific studies and guidelines, vaccines for day-old chicks should be administered based on the level of maternal antibodies against the recommended vaccines to achieve maximum immunity. For example, the recommended vaccination time for Gumboro disease is at least 11 days post-hatch, while for Newcastle disease, it should be at 7 days of age.
• Booster Vaccination for poultry: There are several reasons why a flock may require a booster vaccination:
  • o Duration of Immunity (DOI): The protective effect of a vaccine decreases over time. Most poultry vaccines reach peak response within 2-6 weeks after vaccination, and then the level of protection gradually declines. Booster vaccinations at appropriate intervals help maintain optimal antibody levels and minimize disease risk.
  • o Achieving Uniform Antibody Titers: Ensuring uniform vaccination within a flock is crucial. Some birds may have lower antibody titers than the protective level after vaccination, particularly during disease outbreaks. Boosters help achieve uniform vaccination.
  • o Different Disease Strains: Different vaccines may be used at different times to protect against various strains of a disease.
  • o Using Different Commercial Brands: Similar to human vaccines, using different vaccine brands for boosters can provide broader immunity. This approach ensures that the entire flock is protected.
• Selecting the Appropriate Vaccine: Choosing the right vaccine for a specific disease and bird age is crucial for successful vaccination. To select suitable vaccines, identify the prevalent diseases in your region. Vaccinating against diseases that are not common in your area may not be cost-effective. Additionally, you can sometimes use attenuated vaccines for less prevalent diseases, depending on regional conditions.

Some diseases, like Gumboro and Salmonella, have various serotypes. The prevalence of serotypes varies by region. Identifying the circulating pathogens in the region is essential for vaccine production. Therefore, manufacturers use locally isolated antigens to produce vaccines. Using vaccines without local antigens increases the risk of disease outbreaks in the region.

• Precise Timing: Adhering to a strict vaccination schedule is crucial for developing lasting immunity. Ensure all team members are informed a day prior to vaccination and that all equipment is ready. Poultry vaccinations are best performed during the cooler parts of the day, such as morning or late afternoon. This is the most comfortable time for birds. Vaccinating during hot periods, when birds are stressed by heat, can reduce vaccination effectiveness. Additionally, the bird’s age is a critical factor in vaccination.
• Appropriate Vaccination Age: Young chicks may lack the necessary receptors for certain vaccine antigens due to the gradual development of their immune system. Some receptors, like those for Newcastle disease, infectious bronchitis, and Bursa disease, develop early. Others, like additional Bursa disease receptors, develop later. It is recommended to vaccinate birds after their receptors have fully developed, as the absence of receptors for an antigen in the host can lead to vaccination failure.
• Public Health Flock health: Birds maintained in clean, sanitary conditions exhibit a stronger immune response to vaccinations.

• Stress Reduction or Minimizing stress in flocks: Avoid excessive movement of birds during vaccination. Chickens are creatures of habit and prefer familiar feeding and drinking areas. Dimming the lights can help reduce stress. When administering injections or eye drops, start at one end of the coop and work your way to the other, creating a small empty space first. This allows for a calm and organized vaccination process. Reducing light levels can also help keep birds calm and prevent vaccinated and unvaccinated birds from mixing.
• Proper Vaccination and Techniques Vaccination methods: The correct vaccination technique depends on the type of vaccine and the birds’ age. Vaccination should always be performed by experienced professionals. Consistent poultry vaccination practices by skilled individuals ensure a uniform immune response within the flock
• Quality and Storage Proper maintenance and cold chain temperature: Vaccines must be stored and transported according to the manufacturer’s specific guidelines. Temperature fluctuations can significantly impact a vaccine’s effectiveness. The appropriate cold chain temperature must be strictly maintained to ensure the vaccine remains viable. Various factors can influence the cold chain temperature, including power outages, insufficient refrigeration, excessive cold, and a shortage of vaccine transportation equipment. Additionally, extremely cold temperatures can reduce the potency of oil-based vaccines due to the formation of adjuvant crystals.

Furthermore, it’s crucial to store vaccines separately from other substances like food, chemicals, and biological samples. Some vaccines, such as Marek’s disease vaccine, are particularly sensitive to improper handling and can become inactive.

Thermostatic vaccines are designed to withstand temperature variations, making them suitable for both cold and warm environments. However, freeze-dried vaccines require storage in a refrigerator at 4 degrees Celsius and should be transported using ice packs or cooling systems to maintain temperature. Thermostatic vaccines offer a potential solution to address the challenges associated with cold chain management and storage temperature.

• Use of Adjuvants: An adjuvant is a component added to a vaccine that enhances its effectiveness. It works by boosting the body’s immune response to the specific antigen (the part of the microbe that triggers an immune response) in the vaccine. In simpler terms, an adjuvant helps the vaccine “work harder” by stimulating the immune system to produce more antibodies and provide longer-lasting protection. Adjuvants can also improve the delivery of the antigen to the immune system, ensuring that it reaches the right cells to trigger an immune response. This is particularly important for vaccines given orally, where the antigen can be broken down by stomach acids before it reaches the immune system. By protecting the antigen, adjuvants help ensure that it can stimulate a strong immune response.
• Use of Vaccine Stabilizers: A vaccine stabilizer is an additive used in vaccines to improve their stability and extend their shelf life. Different types of stabilizers are formulated for various vaccine preparations. For instance, live drinking water vaccines for diseases like infectious bronchitis, Newcastle disease, and Gumboro disease commonly use stabilizers such as Vac-Safe (Intervet) and Vital Blue. Additionally, readily available substances like low-fat milk (at a rate of 2 grams per liter) or low-fat dry milk can serve as alternative stabilizers in these vaccines.
• Proper Flock Management: Good flock management practices, such as providing a balanced diet, minimizing stress, and maintaining high standards of hygiene, are essential for successful vaccination outcomes.

When is the best time for poultry vaccination?

The coolest part of the day is generally considered the best time for vaccinating poultry. For vaccinations administered through drinking water, early morning is often the optimal time. For eye or intramuscular injections, low light conditions are also beneficial, and therefore, these vaccinations are usually performed during the late afternoon or evening. It’s important to remember that the vaccination process itself can be stressful for poultry. This stress, combined with the heat stress experienced by birds during hot weather, can significantly impact their well-being. High stress levels can reduce the effectiveness of the vaccine and even increase mortality rates.

Cleaning and Maintenance of Poultry Vaccination Equipment

Clean the vaccination equipment using warm water. It is crucial to avoid using any detergents or disinfectants.
Store all equipment in a sealed plastic bag. If disinfectants have been used, it is essential to thoroughly rinse the equipment with warm water to ensure that no residue remains in the syringes or needles. Disinfectants can inactivate the vaccine, so it is vital to remove all traces of them.

What to do after vaccinating poultry?

After vaccinating your poultry, it’s advisable to slightly increase the ambient temperature by one degree. This is because the bird’s body is working hard to fight off the vaccine and may need extra energy to do so. By increasing the temperature, you can help the birds conserve energy. Additionally, providing your flock with a nutrient-rich diet can be beneficial. However, it’s important to consider the specific feed you’re using. For instance, if you’re using a feed from a company like Jahan Kaveh Ofogh Khazar, which formulates feed based on the birds’ age, you may not need to supplement their diet with additional vitamins or nutrients. Their feed is typically designed to provide all the necessary nutrients for different growth stages.

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How can we ensure the effectiveness of poultry vaccines?

When vaccinating through injection, be sure to check the bird’s body to ensure the vaccine has been injected in the correct place. Or, in eye vaccinations, make sure the vaccine has entered the bird’s eye and has not been spilled. During spray vaccination, the bird’s body should be wet. During vaccination, the bird should react and respond with its head. After vaccination, keep in mind that the only reason for a properly vaccinated flock does not mean that the flock is immune to the disease. To ensure this, you need to evaluate the antibodies produced in the bird’s body. This can be done through the Enzyme-Linked Immunosorbent Assay (ELISA) test. The ELISA test detects the presence of antibodies in the sample. If the antibody level or titer is high in each sample and the titer changes between samples are low, the vaccination has been successful. Keep in mind that it takes 3 weeks after vaccination for the poultry body to produce antibodies. The antibody titer is determined by taking blood from each sample (at least 20 samples are needed). Birds should be selected randomly. The amount of antibody produced by each sample depends on several factors, such as:

• Method of administration: For example, vaccination through drinking water produces a stronger antibody response than spray vaccination.
• Dosage
• Poultry vaccination program: The implementation method of the vaccination stages, such as time management and temperature.
• Bird age
• Bird type
• Nutrition
• Immunosuppression
  

Finally, for each poultry farm, it is important to determine a baseline level of immunity against diseases. This baseline level shows how effective the vaccines given to the birds are and whether the birds’ immune systems are responding adequately to these vaccines.

When evaluating the response to a chicken vaccine, several parameters are considered:
Titers, which are the amount or concentration of antibodies in the blood. The higher the titer, the greater the immunity.
CV (Coefficient of variation) which shows how much the results differ. Here, CV shows the degree of uniformity of the immune response of different birds in a flock. In general, for each disease, CV should be less than 50%.
Comparison of the baseline antibody response with the expected titer: In fact, the level of antibodies in the blood of sample birds is compared with the antibody titer predicted by the vaccine manufacturer. The level of antibodies in the blood of birds is the same as the antibody response and the antibody titer declared by the vaccine manufacturer after vaccination is the same as the expected titer.
Finally, the question arises as to why it is important to evaluate the effectiveness of the vaccine?
The average antibody titer is usually measured for all birds on a farm with a similar vaccination program over a breeding period. By comparing the baseline titer with the expected titer, it can be understood whether the vaccine has been effective enough or not. If the baseline titer is lower than the expected titer, there may be problems with the poultry vaccination program, vaccine quality, or bird health. In such cases, the problem must first be identified so that appropriate measures can be taken, such as changing the vaccine, improving husbandry conditions, or treating sick birds.

What vaccines are essential for chickens?

The vaccination protocol for chickens can vary based on the specific purpose of raising them.
Additionally, it’s crucial to consider the prevalent diseases in your region when developing a vaccination plan. Vaccinating against diseases that are uncommon in your area can lead to unnecessary expenses. It is highly recommended to consult with local veterinarians who specialize in poultry health before implementing any vaccination program.
Refrence:

1. biomedres.us
2. edis.ifas.ufl.edu
3. phitech.pahc.com