STRESSED poultry, like stressed people, experience changes in their body chemistry that affect their health and behavior, according to Kristin Navara, an endocrinologist in the poultry science department at the University of Georgia.
Understanding the mechanisms that trigger these changes — and how to prevent them — can add to the knowledge of how stress affects animals in general, including people.
Navara has spent her career researching how environmental factors — like diet and climate — affect biological chemistry and how that chemistry, in turn, affects the health and lives of people and animals.
In the short term, relaxed chickens are healthier and more productive. Navara said there's a growing consumer demand for meat from "happier" chickens.
"Many people perceive birds' stress through the lens of what they would find stressful," Navara said. However, "birds don't assess stress the same way that humans do."
A free-range environment might seem like a better life to shoppers, but for chickens — who have a tendency toward cannibalism and fight over resources — free-range life actually may be more stressful. Scientists just don't know for sure yet, Navara said.
Currently, Navara is working with chickens and finches to test a range of enrichment tools like nesting boxes and shiny bird toys to see what helps the birds relax.
Studying chickens gives endocrinologists like Navara and geneticists a good model for research since the birds are easy to keep and reproduce quickly.
"We do basic research in a chicken model, but so much of this research can be used to understand other animals or how these issues affect human health," she said.
For instance, Navara's earlier research focused on how climate and seasonal changes correlate to different ratios of male and female offspring for many types of organisms, including people.
She further extended this sex ratio research into chickens because poultry producers are interested in finding out what type of diet would induce hens to produce more female chicks. It's known that diet and stress affect the hormone levels in child-bearing females and can affect the sex and health of the offspring.
For instance, researchers have found that parrots in the wild produce more male offspring when food is plentiful. The physiological mechanism that contributes to that kind of phenomenon is what Navara is trying to decipher through her work with chickens.