A great variety of diseases can influence the welfare and production of laying and breeding hens. Vaccines are an important tool for preventing these diseases, maintaining the welfare of the birds, and ensuring proper growth and optimal production rates in the subsequent production phase.

Laying hens are especially susceptible to diseases in the raising phase. During this period, the birds are growing and developing rapidly, and their immune system is still maturing. Therefore, it is essential to guarantee development during this phase and to vaccinate hens throughout the rearing phase to provide adequate protection against diseases that may occur during this and subsequent production stages. However, the immunological response to vaccination may be limited, thus it is critical to increasing it.

Principal vaccines administered in the rearing phase of layers

Vaccination programmes for laying hens and/or breeders in the rearing phase usually include multiple vaccines, among which the most important are:

• Marek: This disease is caused by an alphaherpesvirus, which can result in tumours, such as lymphomas in poultry nerves and other organs. The vaccine against Marek’s disease is administered to chicks on day one of life or at ten weeks of age, depending on the prevalence in the region and the type of vaccine.
• Gumboro: This disease is caused by a virus (IBD), which can cause an increased mortality rate, as well as immunosuppression, especially between 3-6 weeks of age. The vaccine against Gumboro disease is administered to the pullets at day one of life or at two weeks of age, also depending on the type of vaccine, with subsequent revaccinations, such as at week ten or from 18 to 20 weeks.
• Fowlpox: This disease is caused by a poxvirus that can lead to lesions on the skin and in the mucosae of poultry. The fowlpox vaccine is usually administered to pullets between 10-16 weeks of age.
• Newcastle: This disease is caused by a highly contagious paramyxovirus, which can lead to high mortality of poultry. Signs vary between respiratory (wheezing, coughing, respiratory sounds), neurologic (depression, paralysis), eye and neck inflammation, diarrhoea, altered egg production, as well as shell changes. The Newcastle vaccine is administered to pullets from week one, with repetitions between weeks 7 and 18, which may vary according to the type of vaccine.
• Infectious bronchitis: This disease is caused by a coronavirus (IBV) that can cause a decrease in egg production and high mortality. Signs depend on the tropism of the virus strain for different tissues but vary from respiratory to renal and reproductive, with impaired laying and shell quality. The infectious bronchitis vaccine is administered repeatedly from 1 to 18 weeks of age.

In addition to these basic vaccines, additional vaccines can also be administered depending on the epidemiological situation of each farm or region. For example, if the farm is located in an area with a high prevalence of Salmonella, a vaccine against this bacterium can be administered. The same applies to diseases such as mycoplasmosis, avian encephalomyelitis, laryngotracheitis and others.

It is important to follow the recommendations of the veterinarian to ensure the effectiveness of the vaccination. Serological tests are also necessary to monitor the response to vaccination and to make corrections to the vaccination programme if needed or to identify possible failures and their causes.

Boosting vaccine response with immunostimulant pronutrients

Well-designed vaccination programmes are an essential part of layer health management, as they can help protect birds from serious diseases, prevent secondary processes, and ensure their health and productivity.

However, given the variety and multitude of factors that influence the immune response to vaccination, a booster based on immunostimulant pronutrient supplementation is recommended during the hen’s rearing phase.

They are active natural molecules which can both enhance the specific immune response created by vaccination and prevent immunodeficiency disorders. When administered in combination with vaccination, they increase the synthesis of antibodies, which enhances the birds’ resistance to major poultry diseases, such as those described and included in the usual vaccination programmes for rearing hens.

This effect has been demonstrated in several tests against the main diseases affecting layer and breeder farms. The graph below shows the results of a trial with breeding hens where immunostimulant pronutrients were administered five days before and five days after vaccination. All pullets were vaccinated at 15 weeks of age, in the rearing phase, against infectious bronchitis (IBV), Gumboro disease (IBD) and Newcastle disease (NDV). To monitor the effects of immunostimulant pronutrients on immunisation, blood samples were taken at 33 weeks of age in the production phase.

The use of these pronutrients at the time of vaccination resulted in between 22.41% and 45.15% more antibodies for infectious bronchitis, between 43.46% and 78.95% more antibodies for Gumboro disease, and between 23.49% and 40.45% more antibodies for Newcastle disease.

Conclusions

As part of poultry health management, vaccination programs are essential for layers during the rearing stage. Vaccines can help to protect the birds from serious diseases and enhance their welfare and productivity. However, due to the wide range of factors involved in the production of an immune response associated with vaccination, immunostimulatory pronutrient supplementation is recommended before and after the administration of vaccines. This strategy guarantees an increase in the production of specific antibodies, increasing the proportion of birds protected against these diseases. An improvement in the production and economic indices also demonstrates the effectiveness of this method.