Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/3/2007
Publication Date: 1/15/2008
Citation: Viscione, K.A., Branton, S.L., Vance, A.M., Gerard, P.D., Whitmarsh, S.K., Peebles, E.D. 2008. Effects of 6/85-strain Mycoplasma gallisepticum inoculation alone at 10 weeks of age or in conjunction with F-strain Mycoplasma gallisepticum inoculation overlays at 22 or 45 weeks of age on the performance of commercial egg-laying hens. Poultry Science. 87:588-593. Interpretive Summary: Mycoplasma gallisepticum (MG) infection of layer hens results in a loss of approximately 16 eggs over a 45 week laying cycle; this amounts to a total estimated annual loss of almost $140 million to the commercial table egg industry. Efforts to stem these losses include the use of usually one of three USDA-approved and licensed, live MG vaccines. However, each of these vaccines has both limitations and specific strengths which make none ideal for use in the poultry industry. The present study was conducted to determine whether tandem use of two of the vaccines in layer chickens would detrimentally impact egg production, egg weight and selected egg and eggshell quality parameters. The most important result of the study shows that overlay vaccination of hens at 45 weeks of age with F strain MG vaccine onto hens previously inoculated as pullets at ten weeks of age with 6/85 strain MG does not result in an immediate decrease in egg production and further, may provide continual protection against decreases in egg production.
Technical Abstract: The effects of 6/85-strain M. gallisepticum (6/85MG) inoculation alone or in conjunction with a F-strain M. gallisepticum (FMG) over-lay and its timing on the performance of commercial egg laying hens were investigated. Control birds received sham inoculations at 10 wk of age. A second treated group of birds were inoculated with 6/85MG at 10 wk of age, a third treatment group of birds were inoculated with 6/85MG at 10 wk and received an overlay of FMG at 22 wk, and a fourth treatment group were inoculated with 6/85MG at 10 wk followed by a 45 wk overlay inoculation of FMG. Parameters investigated between 20 and 55 wk of age included BW, mortality, weekly and total egg production, egg weight, relative eggshell conductance, eggshell weight per unit of surface area, percentage shell weight, yolk/albumen ratio, and egg shape index. Hen age effects were reported for BW, egg weight, yolk/albumen ratio, and egg production. No treatment effects or hen age by treatment interactions were noted for those parameters except for yolk/albumen ratio, and no significant effects of any kind were noted for the remaining parameters examined. At wk 47, a significant treatment effect for yolk/albumen ratio was noted. The yolk/albumen ratio in the group of birds that received 6/85MG at 10 wk followed by an overlay of FMG at 22 wk was significantly lower than the sham control birds and those that were inoculated with 6/85MG at 10 wk followed by a 45 wk overlay inoculation of FMG. Pre-lay 6/85MG inoculations may be a suitable substitute for pre-lay FMG inoculations, and FMG overlays during lay on pre-lay 6/85MG inoculations may provide continual protection without eliciting any subsequent suppressive effects on performance.