Researchers demonstrate Campylobacter reduction in chickens

Danish researchers have achieved a reduction in Campylobacter in chickens by adding additives to their feed.

Scientists from DTU National Food Institute conducted trials at a free-range chicken farm in Jutland. Campylobacter prevalence in free-range broilers is usually higher than in conventional flocks.

Trials demonstrate that adding biochar to chicken feed can reduce Campylobacter in chickens by up to 80 percent. This could lead to fewer foodborne infections in people. There are 5,000 registered cases of Campylobacter-related illness annually in Denmark and many more go unreported. Biochar is made from organic waste material, such as wood, and is transformed through pyrolysis, a thermal treatment in an oxygen-depleted atmosphere.

The study, published in the journal Poultry Science, showed an initial increase in Campylobacter jejuni counts on day 36 before a reduction on day 59, suggesting that biochar in the intestine of broilers may need a continuous and longer duration of administration to reduce Campylobacter.

“Reducing bacterial levels in chickens can make a significant difference in public health. Our findings highlight biochar’s potential — particularly for free-range and organic chickens, where controlling bacteria is more challenging than in conventionally raised poultry,” said senior researcher Brian Lassen from DTU National Food Institute, leader of the SafeChicken project.

Testing lab findings
Previous studies conducted in laboratories have shown positive outcomes but struggled to replicate such findings under real world farm management conditions.

“We demonstrate that it’s possible to achieve a significant reduction in Campylobacter in free-range chickens slaughtered at two months of age without finding adverse effects on their health. This is significant for production systems where chickens have access to outdoor areas, which typically increases their exposure to Campylobacter from the environment,” said PhD student Cristina Calvo-Fernandez.

A total of 140 broilers were placed into five cages. They had access to outdoor areas after day 36. Three groups received standard feed supplemented with either biochar 2 percent, a probiotic-like product 0.125 percent, or 15 percent oat hulls. One group received organic acids added to water, and the control group was fed feed pellets and water. For the three successive flocks tested, all broilers became Campylobacter-positive before access to the outdoors. 

Half of the broilers were killed on day 36 and the rest on day 56 for enumeration and isolation of Campylobacter in cecal contents by culturing. Air samples were collected weekly, and water and boot sock samples were collected on days four, 36, and 59.

Researchers tested feed and water additives that had previously shown evidence of reducing Campylobacter under experimental conditions. Trials were conducted three times on the same farm from June to December 2022. The best results came from using biochar.

Researchers also tested organic acids added to the chickens’ drinking water.

“In our trials, we observed a 76 percent reduction in Campylobacter when the chickens were 36 days old — half of this breed’s slaughter age — but the effect diminished by the slaughter age of the free-range chickens three weeks later. This suggests that timing the administration of organic acids may need to be optimized from the experimental setup,” said Calvo-Fernandez.

The SafeChicken project continues until autumn 2025 and is investigating additional methods to combat Campylobacter, including interventions at slaughterhouses. The team is also analyzing why biochar reduces Campylobacter in chickens.

Norwegian project
Meanwhile, another project in Norway is hoping to develop more effective measures for Campylobacter control in the poultry industry.

Animalia is leading the CampySafe project with help from Nortura, Den Stolte Hane, Norsk Kylling, Nærbø Kyllingslakt, Berika, Gårdsand, the Norwegian Veterinary Institute, NMBU Veterinary College and KLF.

Current steps in the Norwegian action plan against Campylobacter in the poultry sector are effective but expensive. The main measure is to freeze meat from infected chickens for at least three weeks to kill the bacteria.

Since 2001, the poultry industry has monitored Campylobacter in chickens on farms, but little is known about its presence in meat. The project will map Campylobacter in chicken carcasses during the slaughtering and cooling process to provide knowledge about which measures reduce bacterial levels.

“Campylobacter is the biggest challenge for food safety in broiler chicken production. CampySafe focuses on Campylobacter control during slaughter, cooling and freezing, and especially on operational solutions that provide increased profitability for the industry. This should not come at the expense of food safety and meat quality,” said Sigrun Hauge, head of food safety at Animalia and project manager for CampySafe.

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Source: https://www.foodsafetynews.com/2025/02/researchers-demonstrate-campylobacter-reduction-in-chickens/