Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/28/2008
Publication Date: 6/15/2008
Citation: Vance, A.M., Branton, S.L., Collier, S.D., Gerard, P.D., Peebles, E.D. 2008. Effects of prelay ts11-strain Mycoplasma gallisepticum inoculation and time specific F-strain Mycoplasma gallisepticum inoculation overlays on internal egg and eggshell characteristics of commercial laying hens. Poultry Science 87:1358-1363. Interpretive Summary: Mycoplasma gallisepticum (MG) is a bacteria that infects approximately 85% of the commercial table egg layer chickens in the U.S. Once infected, chickens remain infected for life and no antibiotic is effective in removing it from the chicken. Its presence is estimated to cost the industry in excess of $140 million annually with the loss primarily attributable to decreased egg production of approximately 16 eggs/hen although internal egg characteristics are also impacted. Three commercial vaccines are available to the poultry industry’s layer sector to combat these losses. However, each of these vaccines has specific strengths and weaknesses with none being an “ideal” vaccine. The present study was conducted to determine whether the use of two of the three vaccines used in conjunction with one another would provide better protection than either used singly. Results of this study show that changes were observed in layer yolk fatty acid profiles in response to prelay inoculation with either one vaccine alone or in conjunction with inoculation with the second vaccine during lay and these changes may be manifested by disturbances in fatty acid synthesis. These results may ultimately aid understanding of the physiological changes induced in the chicken by the organism.
Technical Abstract: Mycoplasma infections are pandemic in multiage layer chicken flocks with M. gallisepticum being the species of greatest concern to commercial egg producers. Live M. gallisepticum vaccines are presently being used to help control M. gallisepticum outbreaks. However, vaccination of layers with F-strain M. gallisepticum may adversely affect egg production. In the present study, 2 trials were conducted to compare the effects of 2 currently available live Mycoplasma vaccines (ts11- and F-strains), used in conjunction, on internal egg and eggshell characteristics. The following 4 inoculation treatments were utilized: 1) sham at 10 wk of age (control), 2) ts11 at 10 wk, 3) ts11 at 10 wk overlaid by F at 22 wk, and 4) ts11 at 10 wk overlaid by F at 45 wk. In each trial at various ages between 23 and 57 wk of age, percent yolk weight, percent yolk moisture, percent yolk lipid, percent albumen weight, Haugh unit scores, and percent shell weight of eggs were assessed. At wk 32, percent yolk lipid was increased in eggs belonging to the ts11 at 10 wk and ts11 at 10 wk overlaid by F at 22 wk treatment groups in comparison to controls. There was also a significant decrease in percent albumen weight in eggs in the ts11 at 10 wk overlaid by F at 22 wk treatment and a decrease in Haugh unit scores in the ts11 at 10 wk treatment in comparison to controls during postpeak lay. Percent yolk moisture, percent egg yolk weight, and percent eggshell weight in layers were not significantly affected by a 10 wk ts11 inoculation alone or in conjunction with subsequent overlay inoculations of F during lay. It is suggested that a 10 wk inoculation of commercial layers with ts11-strain M. gallisepticum may reduce the negative impacts of a prelay F-strain M. gallisepticum inoculation on performance while providing protection against subsequent field strain M. gallisepticum infections.