Location: Food and Feed Safety Research
Project Number: 3091-32000-037-003-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2020
End Date: Aug 31, 2025
Objective:
To daily feed Competitive Exclusion culture to Salmonella inoculated egg laying hens in order to determine Salmonella on the eggshell surface and internal contents.
Approach:
Leghorn layers will be obtained from a local commercial facility at 50+ weeks of age and housed at the USDA-ARS facility with one layer per pen. Hens will be provided free access to water and a balanced unmedicated mash layer feed ration. Fecal samples will be collected from the hens to verify the Salmonella status. Hens that test positive for Salmonella upon entry to the facilities will be removed from the study. In addition, hens that were housed in the cages, on either side of the positive hen's cage, will also be removed from the study. Hens will be allowed to acclimate for one week and then randomly assigned to two treatment groups of 36 birds per treatment. At Day 1, Competitive Exclusion cultures added to feed will be provided to the hens in group two, per National Research Council (NPC) specifications. On Day 3, all hens in each group will be orally challenged with 1 mL of inoculum containing 1 x 107 Colony Forming Units (CFU) of nitric oxide and nalidixic acid-resistant Salmonella Enteritidis. Eggs will be collected from layers three days per week for 35 days post inoculation, cultured, and analyzed for Salmonella prevalence on the shell, as well as internally.
