UGA researchers study how free-range chickens influence farm sustainability

Tracking pathogens in free-range and pastured systems

In addition to DNA sampling, the project will uncover likely sources of chicken exposure to Salmonella and Campylobacter bacteria, which can make people sick, using whole-genome pathogen sequencing and landscape modeling. Exploring technology to help small farmers improve and diversify their production practices is one step toward improving the sustainability of smaller-scale producers.

"The farmers we're working with are often selling directly to restaurants, farmers markets and the public through community-supported agriculture. To bring people to their farms or serve the needs of restaurants or fill their stand at the farmer's market, they need to have all different types of products," Snyder explained. "The diversity of products helps to make their farms more sustainable."

A pilot study Varriano performed in Georgia revealed that chickens can consume hundreds of different types of prey on farms.

The team has performed similar work in the Western U.S. between Southern California and Canada to create a broad footprint in different climates to determine what is typical for the Southeast versus other regions.

"If you have a chicken that's stationary versus a chicken that is free-roaming, we're trying to predict what their differences in diet will be. In a certain setting, are they going to really focus on one certain pest or weed?" Snyder said.

Gathering data from smaller flocks through citizen science

Later in the study, Varriano and Snyder will solicit citizen-scientist input to the study by asking farmers throughout the region to self-submit information about their operations as well as fecal samples from their chickens.

Providing kits similar to those used for genetic genealogy, the researchers will solicit samples from small or backyard flocks.

"We'll extract the DNA and do the sequencing, and then we'll be able to tell them exactly what chickens on their farms - these are the five top weeds they're eating, these are the five top pests and insects that they're eating," Snyder said. "That helps the farmers because they usually don't know what additional benefit they are really getting from these systems; we'll be able to tell them that."

The team plans to create a service center with testing technology to quickly analyze the DNA samples and the many contributors to each sample, whether plant or insect.

"We can get back, from one farm, more than 200 weeds and insects and other arthropods that the chickens are eating, so we are trying to automate that process," he said, adding that preliminary studies in Georgia have shown that chickens are eating Palmer amaranth, one of the most damaging weeds for producers.

"It does really seem like there are some certain things they really are picking out. When they're really confined, chickens do just clear out everything. But when they're foraging freely, it does seem like chickens have things they really like, such as pest caterpillars," Snyder said.

Examining how diversification contributes to sustainable farming

The researchers also will monitor how soil quality changes when pastured chickens are moved from area to area on farms by performing full soil-quality tests to look at the weed seed bank and extracting DNA from the soil to look at microbial biodiversity.

"Chickens, presumably, when they're coming through and pooping, they're dropping a lot of nitrogen, and that's probably changing the soil microbiome. And is that beneficial? Is it building up?" Snyder said. "There's some decent evidence that when you have greater biodiversity and microbes, it makes it harder for pathogens to persist. So are they actually building up the health of the soil in a really general way, not just with nitrogen, but also microbial biodiversity."

A collaborator in the UGA College of Veterinary Medicine, Nikki Shariat, an associate professor in the Department of Population Health, Poultry Diagnostic and Research Center, will test samples for the presence of Salmonella and Campylobacter. By performing whole-genome sequencing on the bacteria, they can determine where the foodborne illness-causing bacteria originated in the farm environment.

"Where on the farm might they be picking these things up? We want to see how often they are present to get some idea of what the incidence would be," Snyder added. "We want to give the growers a full picture - here are the pests the chickens are eating, here are the beneficials they're eating, here's your food safety risk."

Enhancing local food systems and farm profitability

The findings have the potential to benefit growing local food systems in populated areas.

"Economically, if you have 10 acres that you're farming instead of 1,000 acres, you have to know how to generate enough income. That comes down to diversification," Snyder said, adding that "chickens in these systems are providing eggs or meat that you can sell, they're providing fertilizer and they're providing pest and weed control.

"When you're trying to keep costs low and reduce off-farm inputs as much as you can, if more of that can be produced on farm, it's better for the producer. We are helping those things work together," he said.