IMPORTANT: If you reside in a country where health product communications are restricted to health care professionals, and you are NOT a health care professional, please contact your veterinarian instead of reading the following information.

Optimizing Egg Production*


The global layer industry produces billions of food eggs per year, numbers expected to grow as consumer demand increases for this high-value, cost-effective protein source, while breeder operations are the backbone of the equally robust broiler market. To meet all these needs, poultry businesses must maximize egg production by ensuring the health of their laying hens and the quality of the eggs produced.

Nutrition, light levels, and environmental stressors all play a role in layer and breeder productivity, but the biggest challenges that these operations face are the numerous viral and bacterial pathogens that threaten egg production quantitatively, qualitatively, or in terms of laying bird mortality. A strategic vaccination plan must account for the full life cycle of these birds in order to optimize health and productivity.


Disease Management Approaches

Some of the biggest health threats to the overall poultry industry also have particular impact on egg production. Respiratory diseases are especially significant: Newcastle disease, avian influenza, infectious bronchitis, and many other respiratory pathogens frequently cause reduced egg production and/or eggshell abnormalities—as do Marek’s and infectious bursal (Gumboro) disease (IBD), even in their sub-clinical forms. Egg drop syndrome is a viral infection that causes no clinical disease, but results in soft-shelled or shell-less eggs. And layer hens may experience higher mortality rates with both infectious bronchitis and Marek’s disease. In addition, while food-borne pathogens like Salmonella may not affect laying productivity, they have tremendous economic impact on the egg industry.

Vaccines can help prevent and control all these diseases, but combining them into effective vaccination protocols for layers and breeders is complex. While broiler birds have a short life with fairly straightforward goals—targeting 5-6 weeks of disease-free growth—laying hens, in contrast, will spend a year or more in production. Their longer lives translate to a much longer period of susceptibility to many diseases and require a longer duration of immunity from vaccines. Choosing the right combination of live, inactivated, and/or vector vaccines and the timing to deliver them requires specialized expertise and careful planning.

For egg layers, vaccination is mostly scheduled for the first 15 or so weeks of life before birds reach maturity—which means selecting the right combination of vaccines (depending on regional epidemiology) to administer within a very short time period. Once hens begin laying, vaccines are minimal, beyond necessary inactivated boosters to extend immunity for key diseases. With breeder birds, timing of vaccination must be aligned with laying periods, to optimize the long-lasting immunity, and therefore the passing on of maternal antibodies to progeny, especially for IBD, Reovirus, and chicken anemia.


Merial’s Solutions**

Our product portfolio includes a wide selection of vaccines of highly regarded efficacy and quality to help prevent and control many of the diseases that affect commercial egg production. Some of our top brands in this area (often available across multiple regions**) include:

  • AVINEW® a live attenuated virus of Newcastle disease (also available in some markets** in NeO effervescent tablets)
  • BIORAL H120, a live attenuated virus of infectious bronchitis, H120 strain (also available in some markets** in NeO effervescent tablets)
  • GALLIVAC IB88, a live attenuated virus of infectious bronchitis, CR88121 strain (also available in some markets** in NeO effervescent tablets)
  • TROVAC vector vaccines, against Newcastle disease and avian influenza
  • GALLIMUNE range, our multi-region line of inactivated vaccines against various respiratory and other pathogens (including many combination products)
  • VAXXITEK® HVT + IBD, our globally marketed,*** advanced two-in-one vector vaccine against both infectious bursal (Gumboro) disease and Marek’s disease (serotype 3)
  • CRYOMAREX RISPENS or RISPENS, our multi-region product line of live, attenuated Marek’s Rispens (serotype 1) strains, some in combination with other serotypes (brand name varies by market**)

And we offer numerous additional live and inactivated vaccines for the spectrum of threats to egg production, including the above diseases, other respiratory pathogens, and salmonella. Brand and product availability varies from region to region, but we are always evolving our portfolio to address new challenges and changing epidemiologic conditions.
When it comes to optimizing egg production for our layer and breeder customers, as important as Merial’s vaccines is the expertise of our Veterinary Services teams. Leveraging deep knowledge of the full range of poultry diseases and scientific evidence on vaccine performance, these avian health specialists develop customized vaccination programs uniquely calibrated for long-lived flocks. And Merial's Vaccination Technologies & Services (VTS) group provide innovative equipment and dedicated on-site support to ensure any program’s ongoing success.


Key Poultry Diseases Affecting Egg Production*

IMPORTANT: Following are the top diseases affecting egg production that Merial focuses on, but be aware that we do not offer products for all these diseases in all regions, and may offer local products for other egg production concerns. To learn about complete product options in your country, talk to your current Merial representative or contact us.


Newcastle Disease*

Caused by the Newcastle disease virus (NDV), this highly contagious respiratory disease infects primarily chickens but also other avian species such as turkeys, with younger birds most susceptible. There are numerous serotypes and strains ranging from low to high virulence, and in addition to the clinical signs of respiratory or neurologic disease, most strains are marked by a reduction in egg quantity and/or quality.

NDV has been found in most regions of the world, but many areas have eradicated it. The disease can be controlled by vaccination, but strain diversity, local regulations, and other vaccination complexities require strategic selection of appropriate vaccines for a particular region, production site, and disease challenge. Merial has developed a deep and comprehensive portfolio of products to address the complexities of effective Newcastle disease vaccination.
Top Merial products:** AVINEW; GALLIMUNE Flu range; TROVAC NDV

More on our approach to Newcastle Disease 


Avian Influenza*

The term “avian influenza” (AI) actually encompasses a large number of viruses that infect domestic poultry as well as other species. AI viruses can be broadly divided into two categories based on pathogenicity. The “high-pathogenic” (HP) forms, which include many of the H5 and H7 strains, spread rapidly and cause severe disease and high mortality—leading to devastating economic losses to poultry businesses and often trade restrictions.
The “low-pathogenic” forms, mostly due to the H9N2 virus, get much less media attention but still have significant economic impact. Although mortality rates are much lower and symptoms milder than HP AI, it still adversely affects bird productivity, including egg production, especially when found in combination with other respiratory diseases. Merial is an industry leader in AI vaccination, providing effective products in adherence with local regulations on control of this public health and economic concern.

Top Merial products:** GALLIMUNE Flu range

More on our approach to Avian Influenza 


Other Respiratory Diseases*

Numerous respiratory pathogens are known to compromise the productivity of laying hens and the quality of laid eggs. These include the viruses that cause infectious bronchitis, avian rhinotracheitis, and avian laryngotracheitis, as well as bacterial agents such as mycoplasma gallisepticum and infectious coryza. Infectious bronchitis is also documented to have higher mortality rates in layer birds, possibly linked to egg peritonitis. Merial offers a variety of vaccine solutions for many of these respiratory threats. 
Top Merial products:** BIORAL H120; GALLIVAC IB88; NEMOVAC; BIO LARYNGO; LT BLEN; GALLIVAC LT; GALLIMUNE MG; MG TS-11; HAEMOVAX; BIO COR 3; Merial Inc. live and inactivated vaccines (U.S. only) for Newcastle disease and infectious bronchitis

More on our approach to Optimizing Poultry Respiratory Health 


Egg Drop Syndrome (EDS)*

Officially named egg drop syndrome ’76 for its year of discovery (1976) in Northern Ireland, this viral disease has since been identified in several regions around the world. It is caused by an adenovirus that originated in ducks and geese and later infected chickens. Birds usually appear otherwise healthy, but infected laying hens produce eggs that are pale in color, soft-shelled, or sometimes even lacking in shells entirely. The effects are similar to those of other diseases (such as Newcastle, avian influenza, and infectious bronchitis), but an absence of other clinical symptoms generally points to EDS. Although internal egg quality generally remains normal, the compromised shells result in product losses of 10-40%.
The EDS virus is transmitted vertically to progeny but remains latent until the bird reaches laying age. It can also be transmitted horizontally within laying flocks, often from contaminated eggs or equipment. Vaccines (primarily inactivated) are available and help prevent disease, but do not reduce viral shed; sanitation measures can help minimize its spread.

Top Merial products:** GALLIMUNE range


Immunosuppressive and Tumoral Diseases*

The two most important immunosuppressive diseases found in chickens are infectious bursal disease (IBD, also known as Gumboro disease), and Marek’s disease. Both are caused by viruses that are widespread globally, although well-controlled by vaccination in many regions of the world. IBD attacks the bursa of Fabricius, an important immune system organ of birds. It causes immunosuppression and a variety of symptoms, including reduced egg production in layers, whose genetics have been found to be more susceptible to IBD. Marek’s disease causes lesions in various tissues, leading to diverse clinical presentations, which include reduced egg production and sometimes much higher mortality rates in layers.
With our flagship product VAXXITEK HVT + IBD offering two-in-one protection against IBD and Marek’s, Merial is a leader in this area of poultry health. Our wider portfolio includes a range of other products, including many to round out comprehensive vaccination programs for longer-lived birds.

Top Merial products:** VAXXITEK HVT + IBD; CRYOMAREX RISPENS; (not recommended for pullets); GALLIMUNE range; BURSAGUARD range

More on our approach to Marek’s Disease

More on our approach to Infectious Bursal (Gumboro) Disease


Food Safety Concerns*

Optimizing egg production is not only about the health of laying hens and maximizing egg quantities. Control of food-borne pathogens like Salmonella is also a top priority for the egg industry. As the industry shifts more and more to a strategy of prevention for these diseases, Merial is playing a growing role, with vaccines to help our customers safeguard the integrity of their food products.

More on our Solutions for Food Safety


*Merial produces and markets several vaccines against various poultry diseases that affect egg production. However, be aware that NOT all aspects of the diseases mentioned on this page are addressed by a vaccine. Always consult the product label for exact vaccine indications.
**Many of Merial’s avian vaccines are only marketed and available in certain countries, sometimes under different trade names. Speak to your Merial representative or contact us to find out what’s available in your region.
***A vaccine product sold under the VAXXITEK® HVT + IBD trade name is available in more than 75 countries worldwide.


To find out exactly which Merial avian products and vaccination equipment options are available in your region, talk to your Merial representative or contact us now.

Top Avian Health Concerns