Effect of Prior Infection with a Different Salmonella Serovar on A Salmonella Enteritidis Infection During Molt.

Authors: Holt, Peter; Gast, Richard

Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/30/2003
Publication Date: 3/15/2004
Citation: Holt, P.S., Gast, R.K. 2004. Effect of Prior Infection with a Different Salmonella Serovar on A Salmonella Enteritidis Infection During Molt. Avian Diseases. 48:160-166.

Interpretive Summary: Induced molting is an extremely important procedure for the table egg industry to achieve a second egg lay from aging layer flocks. It is estimated that over 160 million hens are molted in the U.S. annually. We had previously shown that molting hens via feed removal significantly increased problems with Salmonella enteritidis (SE) and examined various factors which may reduce the SE problem. Studies in commercial flocks found that many different Salmonella strains besides SE can be found in the hens. In the current study, hens were infected salmonellae other than SE before they were molted and infected with SE. It was found that this prior infection significantly reduced the SE problems during molt indicating that certain flock characteristics, in this case Salmonella co-infection, can moderate an SE infection during molt. Further, seeding flocks with non SE salmonellae may be an effective intervention strategy to control SE during this potentially high susceptibility period.

Technical Abstract: Four trials were conducted to evaluate whether prior infection with Salmonella typhimurium or S. muenchen would modify the severity or the transmission of S. enteritidis (SE) challenge in hens undergoing molt via feed withdrawal. Trials 1 and 2, one room of hens was infected with S. typhimurium 5 days prior to feed withdrawal and then both rooms of hens were challenged with SE on day 4 post feed withdrawal. Trials 3 and 4, one room of hens received S. typhimurium or S. muenchen, respectively, 1 day after feed was withdrawn and transmission of SE was evaluated by challenging the center hen in rows of 11 hens/row at 4 days post feed withdrawal with SE and following the progression of the S. enteritidis down the row of hens. In Trials 1 and 2 shedding of the SE challenge was significantly reduced in hens on day 10 post challenge in Trial 1 and on days 3 and 10 post challenge in Trial 2 compared to the hens just subjected to the molt procedure. Significantly fewer SE were recovered in livers/spleens at day 9 post challenge in Trial 2 from hens receiving the prior S. typhimurium infection. In Trial 3, SE transmission was significantly reduced in the hens on days 3, 10 and 24 post challenge and in Trial 4, significantly reduced S. enteritidis transmission was observed on days 3, 10, 17, and 24 post challenge. These results indicate that prior infection of a flock with a non-SE paratyphoid Salmonella can reduce SE problems that may occur during a molt.