COUNTERMEASURES TO PREVENT AND CONTROL AVIAN MYCOPLASMOSIS
Location: Poultry Research
Title: Effects of time specific F-strain Mycoplasma gallisepticum inoculation overlays on pre-lay ts11-strain Mycoplasma gallisepticum inoculation on performance characteristics of commercial laying hens
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 3, 2008
Publication Date: April 25, 2008
Citation: Vance, A.M., Branton, S.L., Collier, S.D., Gerard, P.D., Peebles, E.D. 2008. Effects of time specific F-strain Mycoplasma gallisepticum inoculation overlays on pre-lay ts11-strain Mycoplasma gallisepticum inoculation on performance characteristics of commercial laying hens. Poultry Science. 87:655-660.
Interpretive Summary: Mycoplasma gallisepticum (MG) is a bacterial organism that is endemic within the table egg sector of the commercial poultry industry. The organism is believed to infect approximately 85% of the total egg laying chickens in the U.S. Infection with this organism results in a loss of about 16 eggs per hen over the typical 45 week laying cycle which results in overall annual losses of approximately $140 million. Efforts to reduce these losses include the use of typically one of three available live MG vaccines. None of the three vaccines are ideal and each has specific strengths and weaknesses. Because of these specific strengths and weaknesses, the question has been raised as to whether dual use of two of the three vaccines may yield advantages, particularly impacting egg production. The results of this study shows that use of the ts-11 strain MG vaccine early (before initiation of egg production) actually ameliorates the loss of egg production seen when mycoplasma–free hens are administered F strain MG vaccine at the end of the second trimester of the first laying cycle (45 weeks of age).
Mycoplasma bacteria are virtually ubiquitous in layer chicken flocks and M. gallisepticum is the species of greatest concern to commercial egg producers. Live M. gallisepticum vaccines were initially approved by the USDA for use in commercial layers in 1988 to help control M. gallisepticum outbreaks. In the present study, 2 trials were conducted to determine the effects of 2 currently available live Mycoplasma vaccines (ts11- and F-strains) when used together. The following 4 inoculation treatments were utilized: 1) sham inoculation at 10 wk of age, 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 18 and 57 wk of age, hen mortality; BW; egg weight; egg production; eggshell breaking strength; incidences of egg blood spots, egg meat spots, and eggshell pimpling; and eggshell weight per unit of surface area were assessed. The effects of inoculation treatment on egg weight at 27, 37, and 38 wk were inconsistent and variable. Eggshell pimpling and egg blood spot incidences at 56 wk were highest in eggs belonging to the ts11 at 10 wk/F at 45 wk group. Despite increases in pimpling and blood spot incidences very late in production due to the tsll at 10 wk/F at 45 wk treatment, performance in layers was not adversely affected by a 10 wk ts11 inoculation alone or in conjunction with subsequent overlay inoculations of F during lay. It is, therefore, suggested that the 10 wk inoculation of commercial layers with ts11 may reduce the negative impacts of a pre-lay F inoculation on performance, as reported in earlier studies, while providing protection against subsequent field strain M. gallisepticum infections. Furthermore, the ts11- and F-strain M. gallisepticum treatment combinations may overcome some of the inadequacies that prelay ts11- or F-strain M. gallisepticum vaccines may have when given independently.