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What more can live production do to reduce Salmonella in poultry?

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Successful Salmonella control throughout live poultry production requires an integrated effort, attention to detail and careful follow-through to help processing plants meet more stringent USDA standards, said poultry health experts at a food-safety news conference.

“Everyone in live production has to be on board because a slip-up in one area can wreck all the time and effort put into the rest of the plan,” said Don Waldrip, DVM, senior technical services veterinarian, Zoetis.

Charles Hofacre, DVM, PhD, president of the Southern Poultry Research Group Inc., Athens, Georgia, advised starting with clean broiler breeders because hens can vertically pass Salmonella on to their broiler progeny.

“Make sure you know your pullet source and make sure there isn’t a mouse or darkling beetle infestation. I’ve worked with pullet farms where we’ve had to completely tear out sidewalls and insulation to get rid of beetles to get control of Salmonella,” he said.

Lower the load

Vaccination of breeders, broilers or both can help lower the load of Salmonella going into the processing plant and is especially worth considering for companies with plants in Category 3, both veterinarians said. However, they cautioned that Salmonella in flocks might be more than vaccines can handle if not supplemented with other control measures.

Vaccination can be supplemented, Hofacre said, with the use of products like essential oils, probiotics and organic acids.

“They don’t have a direct effect on Salmonella like a vaccine would have, but I think they stimulate intestinal immunity or make the gut a place that’s less favorable for Salmonella colonization,” he explained.

“It usually requires the use of more than one of these to have any success. An essential oil, for example, might not be very helpful when used alone, but if it’s coupled with the right probiotic or botanical, it may help.”

Waldrip reviewed other steps poultry producers can take as part of an integrated food safety plan targeting Salmonella:

  • Implement tight biosecurity at every poultry farm. That includes restricting the flow of people and protecting flocks from wild birds, rodents and pests, which can all transit Salmonella.1
  • Pay careful attention to cleanliness and disinfection throughout production, especially at the hatchery. “Don’t overlook ventilation and air-handling units. They can pull in Salmonella-contaminated air if not kept clean,” Waldrip said.2
  • Discard dirty broiler breeder eggs or eggs on the floor. They are more likely to have Salmonella.3 Dirty eggs and floor eggs can be prevented by keeping nest boxes clean. A buildup of debris and bacterial load tends to occur over time regardless of rigid sanitation procedures.
  • Take steps at the feed mill to protect all raw ingredients from dust, which can be a major source of Salmonella. In addition to routine cleaning measures at the mill, feed must be heated to 185° F (85 °C)4 and the process can’t be rushed. “Let’s say a producer is running low on feed and the mill speeds up production. Well, the temperature may not get high enough to kill bacteria — including Salmonella,” Waldrip said. “You can’t take shortcuts with this pathogen.”
  • Keep stocking density at reasonable levels — e.g., 5.6 to 7.5 pounds (2.54 to 3.40 kg) live weight/square foot is the National Chicken Council’s welfare standard5 — schedule ample downtime between flocks (at least 14 days) and windrow litter, which all help minimize Salmonella6
  • Maintain a tight control program for coccidiosis, the No. 1 poultry disease. Coccidiosis, a parasitic disease, damages the gut, providing a favorable environment for the colonization of Salmonella There is research indicating that broilers with a healthy intestinal tract harbor less Salmonella,7 Waldrip said.
  • Acidify water for at least 72 hours before processing to the lowest pH possible but not so much that it discourages drinking.8
  • Carefully time feed withdrawal before processing. Feed in the gut increases the risk that contents will contaminate carcasses during processing. If feed is withdrawn too soon, chickens litter-peck, increasing the risk for contracting Salmonella.9
  • Triage flocks. Drag-swab litter to identify flocks that are likely to be negative for Salmonella and process them first to prevent positive flocks from contaminating the plant in between routine cleaning. “Positive flocks should be processed last during the slaughter day so that they do not ‘seed’ the plant in the cycle and contaminate non-Salmonella flocks,” Waldrip said.

Besides a standard operating procedure for Salmonella control, there has to be a way to ensure compliance. “If you’ve got bait boxes out for rodents, someone has to make sure they’ve got bait,” he said. “That’s the kind of little detail that’s essential for a Salmonella control plan to work.”

Waldrip concluded that “If tackling the Salmonella problem sounds like a Herculean and expensive task, it is. But today’s producers can’t afford to skimp on Salmonella control. If FSIS shuts down your plant, it’ll cost a lot more.”



1. Biosecurity procedures in poultry production. World Organisation for Animal Health (OIE).  http://www.oie.int/fileadmin/Home/eng/Health_standards/tahc/current/chapitre_biosecu_poul_production.pdf Accessed Jan. 24, 2019.
2. Mallinson E. Poultry house ventilation part of Salmonella control. WattAgNet.  https://www.wattagnet.com/articles/28724-poultry-house-ventilation-part-of-salmonella-control Accessed Jan. 24, 2019.
3. Poppe C, et al. Salmonella Contamination of Hatching and Table Eggs: A Comparison. Canadian Journal of Veterinary Research 1998; 62: 191-198.
4. Jones FT. A review of practical Salmonella control measures in animal feed. The Journal of Applied Poultry Research, Volume 20, Issue 1, 1 March 2011, Pages 102–113.
5. National Chicken Council Animal Welfare Guidelines and Checklist for Broilers, page 11.  https://www.nationalchickencouncil.org/wp-content/uploads/2017/07/NCC-Welfare-Guidelines-Broilers.pdf , Accessed: Jan. 24, 2019.
6. Gast RK. Frequency and Duration of Fecal Shedding of Salmonella Serovars Heidelberg and Typhimurium by Experimentally Infected Laying Hens Housed in Enriched Colony Cages at Different Stocking Densities,” Avian Diseases 61(3), (3 July 2017). https://doi.org/10.1637/11635-032517-RegR Accessed: Jan. 24, 2019.
7. Da Costa, M, et al. Studies on the interaction of necrotic enteritis severity and Salmonella prevalence in broiler chickens. Abstract, annual meeting, American Association of Avian Pathologists, 2018.
8. Watkins, Susan. Effects of Water Acidification on Broiler Performance. The Poultry Site. 29 October 2004. http://www.thepoultrysite.com/articles/246/effects-of-water-acidification-on-broiler-performance/ Accessed January 24, 2019.
9. Ramirez, A, et al. Effect of Feed Withdrawal on the Incidence of Salmonella in the Crops and Ceca of Market Age Broiler Chickens. 1997 Poultry Science 76:654–656.


Posted on December 26, 2019
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