Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/21/2008
Publication Date: 10/15/2008
Citation: Peebles, E.D., Viscione, K.A., Branton, S.L., Vance, A.M., Gerard, P.D., Whitmarsh, S.K. 2008. Effects of Prelay 6/85-Strain Mycoplasma gallisepticum Inoculation Alone or in Conjunction with the Inoculation of F-Strain Mycoplasma gallisepticum During Lay on the Blood Characteristics of Commercial Egg-Laying Hens. Poultry Science 87(10):2000-2004. Interpretive Summary: There are currently three live Mycoplasma gallisepticum (MG) vaccines available for use by the table egg sector of the U.S. poultry industry. Each is usually administered to layer chickens at approximately 10 weeks of age (WOA). However, the F strain MG vaccine seems to be preferred for use by the table egg industry and in some situations, owners may desire to begin administering F strain to flocks already vaccinated with 6/85 strain MG vaccine although F strain MG has been shown to reduce egg production if hens are exposed to it at the beginning of the third trimester of the first laying cycle (45 WOA). This study was conducted to determine whether the early administration (10 WOA) of the 6/85 strain of MG would prevent the later administration (either 22 or 45 WOA) of F strain MG from impacting specific blood characteristics of hens including hematocrit, serum calcium, plasma protein, triglycerides and cholesterol. Results of the study suggest that the 10 WOA inoculation with 6/85 MG may elevate plasma protein and in conjunction with an F stain MG overlay at 45 WOA, may increase serum calcium concentrations in laying hens. These results enable us to understand more of the mechanism by which even vaccine strains impact egg production and egg and egg shell quality in laying chickens.
Technical Abstract: The effects of 6/85 Mycoplasma gallisepticum (6/85MG) inoculation alone or in conjunction with F-strain M. Gallisepticum (FMG) overlays and their timing on the blood characteristics of commercial egg-laying hens were investigated. Control birds received sham inoculations at 10 wk of age. Birds in a second treatment group were inoculated with 6/85MG at 10 we of age, those in a third treatment group were inoculated with 6/85MG at 10 wk followed by an overlay inoculation of FMG at 22 wk, and those in the fourth treatment group were inoculated with 6/85MG at 10 wk followed by an overlay inoculation of FMG at 45 wk. Parameters investigated at 24, 32, 43, and 47 wk were hematocrit, plasma total protein, and serum calcium, triglycerides, and cholesterol. No signigicant treatment effects were noted for hematocrit, serum triglycerides, and serum cholesterol. However, at wk 32, plasma protein was greater in birds that received 6/85MG at 10 wk or 6/85MG at 22 wk in comparison to controls. Also, at wk 47, serum calcium concentration was greater in birds that received 6/85MG at 10 wk and FMG at 45 wk compared with controls and those that received 6/85MG at 10 wk and FMG at 22 wk. These results suggest that the prelay inoculation of pullets with 6/85MG may subsequently elevate plasma protein, and in conjunction with an FMG overlay at 45 wk, may increase serum calcium concentrations in laying hens.