Dr David Peebles from the Poultry Science Department explains how Mycoplasma gallisepticum can effect egg-laying hens and available vaccination
Mycoplasma gallisepticum (MG) is an economically important respiratory bacterial pathogen in commercial layers. It can colonise systemically, is insidious in nature, and displays resistance to its host’s defence mechanisms. It is, therefore, difficult if not impossible to completely eliminate from the bodily tissues of egg-laying hens (Winner et al., 2000; Bradbury, 2005). Economic implications of MG infection in layers include reduced feed efficiency and egg production, and increased mortality (Mohammed et al., 1987; Branton et al., 1999; Ley, 2008).
The ramifications of these effects become pronounced on multi-age commercial layer operations where eradication of the disease is not feasible. Earlier estimates of annual financial losses to the table egg industry have been approximately $150 million (Patterson, 1994). Live attenuated MG vaccines have been utilised to displace or exclude natural field strain MG infections that are of greater virulence. In accordance with producer preference and manufacturer recommendations, vaccination has been commonly administered by either drinking water, eye drop, or spray (Evans et al., 2013).
The F-strain Mycoplasma gallisepticum vaccine
In 1988, the F-strain of MG (FMG) was the first live attenuated vaccine approved by the United States Department of Agriculture (USDA)-Agricultural Research Service (ARS), for use in commercial egg-laying operations. However, because FMG is pathogenic to turkeys, its use is not allowed in some states and is approved for exclusive use in commercial layers. The use of FMG has proven effective as it has been observed to reduce virulent field strain MG populations (Levisohn and Dykstra, 1987; Kleven et al., 1998), induce a strong serological response (Roberts, 1969) and resistance to airsacculitis (Rodriguez and Kleven, 1980), and to have no adverse effects on subsequent egg production when administered to pullets before the onset of lay (Self, 2012, personal communication).
F-strain Mycoplasma gallisepticum vaccine research
The economic consequences of MG infections, in addition to concerns with animal health and welfare, have caused USDA-ARS to make funding for the control of this disease a major priority. An outcome of making MG-related research a priority of USDA-ARS has been the performance of a series of studies by the laboratory of Dr. E. David Peebles, of the Mississippi State University Poultry Science Department. His has conducted his work in collaboration with the USDA-ARS Poultry Research Unit in Starkville, MS.
The research that Dr. Peebles has conducted over the last 18 years in collaboration with USDA-ARS, has concerned the timing and route of application of the FMG vaccine on the physiology and performance of commercial egg-laying hens. The goal of his research has been to determine optimal application regimens that are necessary to achieve improved bird health and egg-laying performance.
Recent innovation in F-strain Mycoplasma gallisepticum vaccine delivery
In 1992, in ovo, or “in the egg” injection technology was introduced to the poultry industry, and has replaced manual subcutaneous injection for the commercial administration of vaccines. This technology is now the primary means used to vaccinate broilers worldwide (Ricks et al., 1999).
Knowing the availability of this internationally established technology, Peebles and colleagues realised its potential use for the administration of the FMG vaccine to fertile hatching eggs in the subsequent production of commercial table egg-laying hens.
Recent research by Peebles and his collaborators has provided evidence, based on successful hatching rates at lower dosages, that this method exhibits excellent potential for the effective vaccination of layer embryos.
Further research is being conducted to establish the effects of in ovo FMG vaccination on the post-hatch immunity and performance of commercial table egg-laying hens (Elliott et al., 2017). Considerable financial savings are anticipated upon adoption of in ovo FMG application methods by the table egg industry.
References
Bradbury, J. M. 2005. Poultry mycoplasmas: sophisticated pathogens in simple guise. Br. Poult. Sci. 46:125-136.
Branton, S. L., B. D. Lott, J. D. May, W. R. Maslin, G. T. Pharr, J. E. Brown, and D. L. Boykin. 1999. The effects of F-strain Mycoplasma gallisepticum, Mycoplasma synoviae, and the dual infection in commercial layer hens over a 44-week laying cycle when challenged before beginning of lay. II. Egg size distribution. Avian Dis. 43:326-330.
Elliott, K. E. C., S. L. Branton, J. D. Evans, P. D. Gerard, and E. D. Peebles. 2017. Layer chicken embryo survival to hatch when administered an in ovo vaccination of strain F Mycoplasma gallisepticum and locations of bacteria prevalence in the newly hatched chick. Poult. Sci. (dx.doi.org/10.3382/ps/pex196).
Evans, J. D., R. Jacob, S. A. Leigh, S. D. Collier, E. D. Peebles, and S. L. Branton. 2013. Spray application of live attenuated F strain-derived Mycoplasma gallisepticum vacines. J. Appl. Poult. Sci. Res. 22:842-848.
Kleven, S. H., H.-H. Fan, and K. S. Turner. 1998. Pen trial studies on the use of live vaccines to displace virulent Mycoplasma gallisepticum in chickens. Avian Dis. 42:300-306.
Levisohn, S., and M. J. Dykstra. 1987. A quantitative study of single and mixed infection of the chicken trachea by Mycoplasma gallisepticum. Avian Dis. 31:1-12.
Ley D. H. 2008. Mycoplasma gallisepticum infection. Pages 807-834 in: Y. M Saiph, A. M. Fadly, J. R. Glisson, L. R. McDougald,
- K. Nolan, and D. E. Swayne (eds.). Diseases of Poultry. 12th ed. Blackwell Publishing. Press, Ames, IA.
Mohammed, H. O., T. E. Carpenter, and R. Yamamoto. 1987. Economic impact of Mycoplasma gallisepticum and M. synovia in commercial layer flocks. Avian Dis. 31:477-482.
Patterson, P. H. 1994. Coping with Mycoplasma gallisepticum. Internes 7:1-3.
Ricks, C. A., A. Avialian, T. Bryan, R. Gilder sleeve, E. Haddad, R. Illich, S. King, L. Murray, P. Phelps, R. Poston, C. Whitfill, and C. Williams. 1999. In ovo vaccination technology. Adv. Vet. Med. 41:495-515.
Roberts, D. H. 1969. Serological response produced in chickens by three strains of Mycoplasma gallisepticum. J. Appl. Bacterial. 32:395-401.
Rodriguez, R. and S. H. Keven. 1980. Evaluation of a vaccine against Mycoplasma gallisepticum in commercial broilers. Avian Dis. 24:879-889.
Winner, F. R., R. Rosengarten, and C. Citi. 2000. In vitro cell invasion of Mycoplasma gallisepticum. Infect. Immun. 68:4238-4244.
Please note: this is a commerical profile
Dr E. David Peebles
Poultry Science Department
Tel: +1 662 325 3379
http://www.poultry.msstate.edu/
