Colonization Sites of Salmonella Enteritidis and Heidelberg in Broilers when Exposed Continuously in Feed or Day of Hatch
Type of DegreeMaster's Thesis
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Salmonella is the most common bacterial pathogen to cause foodborne illness in the United States with poultry acting as a main vector. In order to control this pathogen prior to the processing plant, consideration must be made in both entryways and colonization sites at the pre-harvest level. For these studies, the first aim was to determine colonization sites within broilers (meat birds) if they were given a constant exposure of Salmonella Enteritidis (SE) or Heidelberg (SH) in their feed at a constant dose of 102 CFU/gram. Supplementary studies included giving broilers either SE or SH on day 0 through one of five inoculation routes (oral, intratracheal, subcutaneous, ocular or cloacal) at 104 CFU.U/mL Birds were reared to market weight, then euthanized and samples collected. The samples included: breast, crop, a pooled sample of the bursa & thymus (B+T), spinal cord, trachea, skin from the neck area, thigh, kidney, a pooled sample of the liver & spleen (L+S), ceca, and crop. Swab samples were collected from the: abdominal cavity (ab cav), lung, bone marrow (bm), and cloaca. A comparison of the recovery of Salmonella per serotype as well as inoculation route was analyzed using the GLM procedure and when appropriate, Tukey HSD (P≤0.05). A comparison of the means for the feed trial was determined by a T-Test. For all three presented studies, there was a greater recovery within the ceca in comparison to other collected samples. Other areas with high recovery included: B+T, crop, cloacal swab. The intra-tracheal inoculation route resulted in the greatest recovery of both SE and SH in comparison to the other investigated inoculation routes. The recovery of SE and SH within the ceca indicates that this is the ideal area for sampling colonization of Salmonella Enteritidis or Heidelberg at the pre-harvest level. The intra-tracheal inoculation route is in need of further analysis to determine this entryway’s level of concern within the poultry industry. This holistic approach of analyzing both entryways and colonization sites will aid the poultry industry in determining pre-harvest control measures for Salmonella.