MICROBIOLOGICAL ANALYSIS OF THE EARLY SALMONELLA-ENTERITIDIS INFECTION IN MOLTED AND UNMOLTED HENS

A study was conducted in which the early kinetics (4 hr to 96 hr) of an infection by Salmonella enteritidis in older white leghorn hens was examined, and a molt was induced through withholding feed to determine its effect on the progression of this infection. Molted and unmolted hens were orally infected with 5-10 x 10(6) S. enteritidis on day 4 of the feed removal. At 4, 24, 48, 72, and 96 hr postinfection, liver, spleen, ileum, colon, cecum, and feces were removed from six hens per group and sampled for the presence of the challenge organism. By 24 hr postinfection, S. enteritidis was most prevalent in the cecum and feces of unmolted hens, and this prevalence continued throughout the experimental period. In molted hens, however, S. enteritidis could be detected in a high percentage (90-100%) of colon, cecum, and feces samples at 24 to 96 hr postinfection and in 67% or more of ileum samples at 48 to 96 hr postinfection, indicating a much wider distribution of the S. enteritidis along the intestinal tract than in unmolted hens. The numbers of S. enteritidis recovered from these alimentary samples were also significantly higher in molted than unmolted hens. S. enteritidis could not be detected in livers or spleens of either treatment group at 4 or 24 hr postinfection. At 48, 72, and 96 hr postinfection, 50% or more of: the livers and spleens in both the molted and unmolted hens were positive for the challenge organism, but significantly more S. enteritidis was recovered from the organs of the molted hens at these three sampling times. These results indicate that induced molting has a profound effect on both intestinal and extraintestinal infection by S. enteritidis, and these effects occur within 24 hr postinfection in the intestine and within 48 hr postinfection in the livers and spleens.