Researchers study major components of antibiotic-restricted poultry production

As poultry companies move away from using antibiotic growth promoters in chickens, scientists at the U.S. Department of Agriculture’s Agricultural Research Service and the University of Arkansas System Division of Agriculture are joining an international research coalition to find new ways to keep the poultry industry sustainable.

According to USDA data, the U.S. broiler industry is the largest in the world, producing 9 billion birds annually. Antibiotic growth promoters have been an integral part of that success, contributing to the industry’s sustained growth, enhancing poultry performance, feed efficiency and general health.

Major poultry producers in the U.S., including Tyson Foods, Simmons Foods and others, were already moving away from the use of AGPs in response to consumer demand, said David Caldwell, head of the poultry science department for the Division of Agriculture and the Dale Bumpers College of Agricultural, Food and Life Sciences.

More recently, a U.S. Food and Drug Administration directive requires AGPs to be phased out in all U.S. poultry production.

Annie Donoghue, research leader for the USDA ARS Poultry Production Product Safety Research Unit, said research is needed to find effective alternatives that can reduce the adverse effects on bird health and mortality, and food safety.

The ARS unit is a research partner of the Arkansas Agricultural Experiment Station, the research arm of the Division of Agriculture, and housed within the Center of Excellence for Poultry Science in Fayetteville.

System-based approach

To address the challenges of sustainable agricultural systems in the U.S., the USDA’s National Institute of Food and Agriculture awarded a total of $90 million for eight projects nationwide this year from its Sustainable Agricultural Systems program. The Arkansas team is part of a $10 million project called “Systems-based Integrated Program for Enhancing the Sustainability of Antibiotic-Restricted Poultry Production.” It includes collaborators from 15 research institutions across the U.S. and in Mexico and India.

The University of Connecticut is the program’s lead institution. The Arkansas team was awarded $1.3 million from the project.

The Arkansas team will be investigating effective alternative means of sustaining bird health, protecting consumers from foodborne illnesses and minimizing impacts on the environment.

The Arkansas team will also develop education and outreach programs to disseminate research-based products and practices for sustainable antibiotic-restricted poultry production, Donoghue said.

Defending against pathogens

AGPs reduce pathogen populations in the chickens. Phasing out antibiotics in poultry production opens the door for higher pathogen loads in the birds. Higher pathogen loads can lead to diseases that harm the chickens and increase foodborne illnesses that can sicken consumers, Donoghue said.

Donoghue, ARS colleague Josh Lyte and Experiment Station researcher Komal Arsi will conduct trials to test the effectiveness of novel systems for delivering phytochemicals and probiotics to control the foodborne pathogens most associated with poultry, Salmonella and Campylobacter jejuni.

These two pathogens are responsible for more than 2 million illnesses in humans annually, Arsi said. They account for two-thirds of the total laboratory-confirmed cases of bacterial gastroenteritis in the U.S.

Previous research at the Center of Excellence for Poultry Science has shown that probiotic products are effective alternatives to antibiotics. They suppress these pathogens and helping to maintain bird health. The phytochemicals are plant compounds like thymol and carvacrol from oregano, trans-cinnamaldehyde from the bark of cinnamon, and eugenol from clove oil.

“Plant-derived compounds are widely used in traditional medicine as preservatives and flavor enhancers in many cultures,” Arsi said. “Ongoing research with these compounds shows that they can provide effective and economically viable alternatives to antibiotics in sustainable animal production systems.”

“Successful completion of this research will provide the poultry industry with effective antimicrobial pathogen control in broiler chickens,” Arsi said. “Ultimately, it will provide strategies to enhance long-term sustainability through improved food security, public health, economic prosperity and better quality of life for small- and medium-scale poultry production in Arkansas and elsewhere.”

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As part of this project, Arsi said she will coordinate with USDA ARS scientists and local farmers to conduct bird studies to test the effectiveness and practical use of alternative feed ingredients, like insect meal, on broiler performance and meat quality. The findings from these studies will provide new sources of poultry feed ingredients that are economically viable and suitable for sustainable poultry production.

Dealing with heat stress

One of the most challenging issues to address in antibiotic-restricted poultry health is heat stress, said Sami Dridi, professor of avian endocrinology and molecular genetics for the Division of Agriculture.

“Chickens have no sweat glands, and modern broiler chickens have high metabolic activity,” Dridi said. “They are very susceptible to heat stress, and heat stress is devastating to poultry production sustainability worldwide because of its adverse effects on growth, health, well-being and mortality. The U.S. poultry industry loses millions of dollars each year due to heat stress.”

Dridi is collaborating with Tom Porter and Shawna Weimer, professors in the animal and avian sciences department at the University of Maryland, to investigate two strategies to help cope with poultry heat stress—nutrition and thermal conditioning.

Heat stress can cause a condition known as “leaky gut,” in which intestinal fluids can leak into the circulatory system, and from there to other tissues in a bird’s body. Dridi said this allows bacterial pathogens to spread to other tissues, where they can cause a variety of illnesses for the chickens or potentially contaminate muscle tissue with foodborne pathogens.

The probiotics and phytogenic compounds that Arsi is investigating as a means to control pathogens also improve overall gut health, Dridi said. “If we can alleviate the stress, make the intestinal barrier integrity stronger and the gut healthier, maybe we can improve the health and well-being of the bird.”

He said that improving the health and well being of the birds will help reinforce the sustainability of the poultry industry.

The use of thermal conditioning to reduce physiological stress inflicted by environmental temperature requires exposing chicks to high temperatures for a short time on the third or fourth day after hatching. Doing so, Dridi said, helps condition the birds to tolerate high temperatures as they mature.

Dridi will compare birds using thermal conditioning and the nutrition plan against birds under standard management practices—a control group—to determine if one or some combination of both novel strategies can relieve heat stress and improve bird health, Dridi said.

Researchers previously evaluated a bird’s response to heat or other stresses with blood tests, Dridi said. But he will be using a new, less invasive technique that analyzes the levels of heat-shock protein in feathers. “Taking a feather sample is quick, convenient, not invasive, and does not require prolonged restraint and associated stress,” Dridi said. “And it allows for ease of monitoring the same animal over time.”

Observing bird behavior can also detect response to heat stress or tolerance, Dridi said. In collaboration with Weimer, of the University of Maryland, Dridi will use video cameras and a vision algorithm to track and analyze chicken behavior.

“Eating generates heat,” Dridi said. “So, if birds are already under heat stress, they need to stop eating to reduce their body core temperature and avoid hyperthermia.”

If birds eat less, they don’t grow as they should, Dridi said, and poultry production is impaired.

It boils down to food production, Dridi said. “World population is growing, and by 2050, to meet human protein needs, meat and egg production will have to increase 73%, according to an FAO (United Nations Food and Agriculture Organization) study.”

Environmental impacts

Donoghue said other ARS researchers in her unit are investigating the impacts of antibiotic-restricted poultry production on the environment.

ARS soil scientist Philip Moore and ARS colleague Lyte will conduct trials to determine the effect of ammonia control products on litter chemistry and emissions of ammonia and greenhouse gases, Donoghue said.

They will also conduct a rainfall simulation study using poultry litter from the first study to determine the effects of these treatments on water quality, emphasizing phosphorus runoff, Donoghue said. These studies will provide valuable information to develop novel methods of improving air quality and litter quality in broiler houses. That information will help develop strategies to promote bird welfare in intensive broiler production.

Amanda Ashworth, also an ARS soil scientist, will conduct field experiments to test whether antibiotic alternatives can reduce the transmission of antibiotic-resistant genes to the environment, Donoghue said. Ashworth will study how these changes to poultry production systems might improve system-wide cost-effectiveness and sustainability through agronomic field trials and a life cycle assessment.

Based on her findings, Ashworth will develop ecologically based management practices for enhancing the sustainability of antibiotic restricted poultry production.


The NIFA AFRI grant includes provisions for getting the word out on the novel technologies and management practices developed by this research, Donoghue said.

Sarah Bramall, a Division of Agriculture program specialist in the Center of Excellence for Poultry Science, is developing courses for outreach and education about the research.

“We want poultry producers in Arkansas and elsewhere to know about the work we’re doing,” Bramall said, adding they will have to understand the results of this research and adopt the new technology and practices that come out of it, she said.

“The poultry industry will have to remain sustainable in order to increase food production to meet future demands,” Bramall said. “But we can’t accomplish this unless we first educate everyone about it.”

Donoghue said the poultry industries are involved in the entire research program. She said stakeholder representatives from poultry producers and agricultural organizations are following the work, providing input to the research teams and, in some cases, providing use of their farms for field tests.

“The poultry industry is at the forefront of research and development aimed at sustainable production practices,” Donoghue said. “We expect this project will continue the tradition of providing the industry with impactful tools to improve bird health, human food safety and environmental stewardship.”