Questions and Answers about MG
What is the average percent of incidence of MG in the layer complexes across the US?
• It is estimated that at least 70% of the larger layer complexes are positive to MG and/or MS. Multiage complexes have a much higher incidence than single age complexes.
Does the commercial layer industry perceive MG as problem they need help in controlling?
• Yes, MG is a constant problem in most multiage layer facilities. MG is considered to be a “Top 3” health issue that complex producers must contend with. MG is definitely a disease for which producers are actively seeking new tools to improve their ability to control the infection and reduce production losses.
Why is MG such a problem in commercial layer complexes?
• As the number and size of the layer farms grew to be predominately large multiple age facilities the industry lost its ability to effectively control MG. The increase of MG infections in commercial layers has coincided with the increase in the number of multiage layer facilities. Currently the majority of the large layer complexes in the USA are multiage. With this management practice birds are on site continuously and because of the inability to depopulate the entire complex at one time the MG maintains a constant presence, re-infecting the new replacement pullets soon after they arrive on site. It may take up to 10 years for MG to first appear on a multiage layer complex but once it occurs it is there to stay due to the multiage management practice.
What are the measures currently used to control MG?
• The three most common practices are vaccination of pullets, the placement of antibiotics against Mycoplasma in the layer feed and biosecurity. Biosecurity has minimal effects on multiage facilities. A very effective tool still seems to be the ability to depopulate an entire facility after each flock. This is demonstrated by the fact that most of the stand-alone single age facilities do not have major MG problems.
What is Vectormune FP-MG
• Vectormune FP-MG is the latest recombinant vectored vaccine developed and manufactured by Biomune Company. This vaccine provides protection to fowl pox and MG. Vectormune FP-MG + AE provides the option of adding AE (avian encephalomyelitis). The fowl pox and the AE components of the vaccine are live viruses but there is not a live MG organism in the vaccine. Specific genes from MG have been placed into the DNA of the fowl poxvirus that serves as a vector with the ability to express protective MG proteins. The MG protection is the result of these protective MG proteins being expressed from the fowl poxvirus as the fowl poxvirus replicates in the bird following a wing web vaccination. This attribute allows for the classification of a “Neighbor Friendly” vaccine as it is incapable of spreading MG to a facility or to any neighboring flocks.
Does the Vectormune FP-MG vaccine stimulate a positive result on the plate agglutination test?
• No. Vectormune FP-MG provides immunity to MG while maintaining a negative plate agglutination result following vaccination.
Are commercial layer breeders vaccinated against MG.
• There is a high level of exposure to MG nationwide in all poultry. Despite this risk most breeders in the USA are not currently being vaccinated. In recent years there have been some commercial layer breeder flocks turning MG positive both in the US and Canada. Unfortunately vaccination of breeders was not an option because of NPIP requirements to stay serologically negative. Vectormune FP-MG is a tool not previously available to the breeder industry since this vaccine provides immunity to MG without stimulating seroconversion and the flocks will maintain their serologically negative status following vaccination.
Has there been any recent change in MG vaccination programs?
• In the last four years MG has been a serious health concern as the wild MG field strains have appeared to become more pathogenic. In an effort to displace these more virulent field strains of MG several producers began vaccinating with F-strain or F-vax with a plan to continue for 1-2 years. Many post vaccination reactions were encountered especially if F-strain was given in within 2 weeks of the Infectious Laryngotracheitis vaccine (or vice versa). Producers moved the F-strain vaccination from 11 weeks to 9 weeks of age and reduced the dose by 50%. Many of these producers are currently switching to Vectormune FP-MG, now that it is available, to provide MG protection without the reactions and to avoid the seeding down of the facility with F-strain.
Are killed MG vaccines used?
• Yes, commercial killed vaccines for MG and autogenous killed MG vaccines are available. Difficulties with administration and suspect efficacy have limited their use to only a few producers.
By what route and at what ages is Vectormune FP-MG given?
• Vectormune FP-MG is administered via wing web stab at 8 weeks of age or older.
When does sero-conversion occur in a non-vaccinated layer flock on a positive complex?
• In an MG positive layer complex sero-conversion of the new replacement pullet flock will appear as early as 3-4 weeks after housing in the layer facility.
When do vaccinated flocks typically become sero-positive for MG?
• Commercial layer flocks that have been vaccinated with a live MG vaccine as Mycovac L then exposed to a field challenge in the layer facility will typically seroconvert to the field challenge between 40-45 weeks of age. Flocks vaccinated with ts-11 are expected to have 50% of the birds seroconverting following vaccination by 18 weeks of age (housing) with 100% seroconversion around 30 weeks of age. With good application F-strain vaccinated flocks should be 100% sero-positive by 3-4 weeks post vaccination and maintain a sero-positive status of greater than 60 % through lay. Flocks vaccinated with Vectormune FP-MG typically will not seroconvert to MG. A very high MG challenge may be detected by having a small percentage of the flock seroconvert on the HI test at 40-50 weeks of age.
What is the economic impact of a MG “outbreak”?
• Losses associated with an out break of MG are due to decreased egg production, poor shell quality and significant increased in mortality for 15 weeks or more duration. Cost increase due to added labor and medication cost. The economic impact of a MG field challenge is estimated to cost producers 5-7 eggs per hen housed to 60 weeks of age. A recent MG outbreak in a non-vaccinated flock documented a loss of 18 eggs per hen housed at 50 weeks of age plus the additional cost of antibiotic medication added to the feed for several weeks. Another report stated 9-10 eggs per hen housed are lost in non-vaccinated flocks plus medication and other expenses due to an MG out break.
• There is also a production loss associated with using live MG vaccines. The use of F-strain vaccine alone will cost a producer 3-5 eggs per hen housed and the use of Mycovac L and ts-11 will cost the producer 1-3 eggs per bird to 60 weeks. There has not been a documented loss of production associated with the use of Vectormune FP-MG.
• The interest is very high and is peak by the fact that Vectormune FP-MG does not contain a live Mycoplasma organism and it provides MG protection without seroconversion. This Vectormune FP-MG vaccine is the latest in a line of “Neighbor Friendly” vectored vaccines that can be safely used without spreading MG to your neighboring poultry flocks. The inability to introduce MG and the efficacy has made Vectormune FP-MG very popular with the industry in a very short period.