|Vance, A - MISSISSIPPI STATE UNIV|
|Gerard, P - CLEMSON UNIVERSITY|
|Peebles, E - MISSISSIPPI STATE UNIV|
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 8, 2009
Publication Date: May 1, 2009
Citation: Vance, A.M., Branton, S.L., Collier, S.D., Gerard, P.D., Peebles, E.D. 2009. Effects of Time Specific F-strain Mycoplasma gallisepticum Inoculation Overlays on Prelay ts11-strain M. gallisepticum Vaccination on Digestive and Reproductive Organ Characteristics of Commercial Egg-Laying Hens. Poultry Science 88(5):980-983. Interpretive Summary: There are three live Mycoplasma gallisepticum (MG) vaccines available for use in the commercial table egg industry. Only one has been shown capable of displacing field or wild strains of MG, an organism that cost producers about 16 eggs/hen over a 45 week laying cycle. Layer complexes typically begin with the utilization of any one of the three vaccine strains. However, if not given initially and when the field challenge is hot (severe), producers may have to utilize the F strain MG vaccine to get control of the field strain but, the F strain can cause a decrease in egg production of approximately 6% when given in the beginning of the third trimester of the first laying cycle (45 weeks of age [WOA]) to uninfected hens. Therefore, the objective of this study was to determine whether an early vaccination (10 WOA) with ts-11 strain MG vaccine would effect liver weight, liver lipid, ovarian weight, and several other parameters which are correlated with poor performance in laying hens. Results of this study confirm that when coupled with F strain MG vaccination at 45 WOA, prelay ts11 MG vaccinations may be a practical substitute for prelay F strain MG vaccination for providing continual protection against field-strain MG infections in layers.
Technical Abstract: Two trials were conducted to determine the effects of a prelay ts11-strain M. gallisepticum (ts11MG) vaccination alone or in conjunction with F-strain M. gallisepticum (FMG) inoculation overlays at 2 different age periods during lay on the digestive and reproductive organ characteristics of commercial egg-laying hens. In each trial, the following 4 treatments were utilized: sham vaccination at 10 wk of age; ts11MG vaccination at 10 wk of age; ts11MG at 10 wk of age overlaid by FMG inoculation at 22 wk of age; and ts11MG at 10 wk of age overlaid by FMG at 45 wk of age. Necropsies were performed at the end of both trials (58 wk of age), using 2 birds from each of 4 replicate units per treatment, to observe treatment effects on the following parameters: liver weight; liver lipid and moisture concentrations; incidence of fatty liver hemorrhagic syndrome; ovary weight; number of mature ovarian follicles; and the total and segmental weights, lengths, and histologies of the oviduct and small intestine. Treatments affected only vaginal length as a percentage of total oviduct length. Vaginas were relatively longer in hens that had only been vaccinated with ts11MG at 10 wk in comparison to all the other treatment groups, including controls. Except for relative vaginal length, the digestive and reproductive organs of layers were not influenced by the ts11MG and FMG treatment regimens imposed in this study. These results confirm that when coupled with FMG inoculations during lay, prelay ts11MG vaccinations may be a practical substitute for prelay FMG inoculations for providing continual protection against field-strain MG infections in layers.