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ARS Home Southeast Area Mississippi State, Mississippi Poultry Research Research





- Evans, Jeffrey - Jeff
- Leigh, Spencer
- Purswell, Joseph - Jody
- Robinson, Kelsy
- 2023
- 2022
- Publications
- Animal Health (103)

Research Project: Control Strategies for Avian Mycoplasmosis **Location:
                            Poultry Research** 2022 Annual Report **Objectives**
                                

1. Investigate the efficacy of different strategies to displace virulent or moderately pathogenic strains of Mycoplasma gallisepticum (MG) with safer or less pathogenic, including vaccine strains, of MG as a means to reduce economic impacts to egg laying facilities.

2. Evaluate the effects of commercial-scale poultry management practices on transmission and microbial ecology of Mycoplasma.

3. Investigate the long-term efficacy of in ovo vaccination strategies to protect against disease caused by MG. **Approach**
                                

To determine the transmissibility of Mycoplasma gallisepticum (MG) under varying conditions relevant to commercial poultry industries, layer chickens will be challenged with virulent and attenuated MG strains and then will be placed among naïve poultry. Transmissibility will be assessed by detection the MG among nonchallenged poultry. To determine the impact of housing system on the transmission rates both conventional cage and non-cage systems will be investigated. Further, among conventional cage systems, the ventilation systems will include both still air and tunnel ventilation. Among the non-cage systems, experiments will be designed to compare poultry housed over open pit, deep pit, and flush tank systems to determine any effects on MG transmissibility. To compare genetic and phenotypic differences between virulent and attenuated strains of MG, MG strains will be sequenced and their genome assembled. Further, comparative proteomics will be performed, and all associated findings will be analyzed to 
elucidate differences which may be applied to future means of MG control. To develop an MG in ovo vaccination protocol and test its’ potential for application towards protection of commercial flocks from MG challenge, experiments will be initially be performed to determine appropriate dosage levels. The effects of the various doses of the MG vaccine on the 18 d embryo will be determined and findings will be applied to the development of a commercially applicable high throughput automated protocol. In addition, chicks derived from the vaccinated eggs will be 
hatched and assessed for afforded protection. **Progress Report**
                                

Initial studies to determine the impact of sampling schedule on in vivo MG populations at 3 anatomical sites have been completed and analyses are underway. The production of the autogenous and electron-beam killed bacterins were initially delayed but are now in progress.  A new incubator facility was brought online to expand research capabilities to test in-ovo vaccination routes for MG protection.  A trial to evaluate temperature measurement to monitor embryo temperatures in layer chicken eggs during incubation was conducted.  The study proved successful with potential to record temperatures within the air cell of an incubated egg as early as 7 days of incubation.  The future work using this technology could be revealing of the interior egg temperature fluctuations in various situations and implications for the newly hatched chick. **Accomplishments**
                                

1. In-ovo temperature monitoring. Current methods to measure embryo temperature during incubation are limited in effectiveness and accuracy.  Miniature dataloggers were inserted into incubating laying hen eggs to evaluate their accuracy and utility.  This method was used to successfully record temperatures within the air cell of an incubated egg as early as 7 days of incubation.  Applications of this methodology can be used to correlate incubation conditions with to early chick immunocompetence to improve incubator management. 2. Novel Electron Beam Killed Vaccine. Newly developed technologies were utilized to produce the initial Electron Beam Irradiation Killed vaccine against Mycoplasma gallisepticum.  Conditions were optimized for production of the whole cell bacterin vaccine and vaccine was stocked for in vivo challenge studies. 3. Sampling impact on in vivo Mycoplasma gallisepticum (MG) populations. General bio-surveillance and the timely monitoring of treatment effects on MG populations requires elucidation of sampling related impacts to clearly discern treatment-related effects. Various sampling schedules were compared to determine the minimal window between events.  This knowledge will be applied to future studies to discern treatment effects on MG. **Review Publications**
                            *Alqhtani, A.H., Fatemi, S.A., Collins Elliott, K.E., Branton, S.L., Evans, J.D., Leigh, S.A., Gerard, P.D., Peebles, E.D. 2022. Effects of the In ovo vaccination of the ts-11 strain of mycoplasma gallisepticum in layer embryos and posthatch chicks. Animals. 2022,12,1120. https://doi.org/10.3390/ani12091120.*


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