Source:University of DelawareSummary:The most delicious-looking broiler chicken could consist of hard, chewy meat. The problem plagues the poultry industry, but researchers have found the cause and mapped a solution. Gene expression irregularities at the onset of ‘wooden breast syndrome’ suggest the disease is a metabolic disorder. The findings could lead to short-term solutions that help growers manage the condition in chickens during production and may inform human health research related to metabolic syndromes, such as diabetes.
University of Delaware researchers have discovered that lipoprotein lipase, an enzyme crucial for fat metabolism, may be contributing to wooden breast syndrome in broiler chickens.
Wooden breast syndrome can affect broiler chickens, making the meat hard and chewy. It is a costly problem that can render the birds unmarketable, causing significant economic losses for growers, who sometimes see the disease in up to half their flocks.
The UD research team, led by Behnam Abasht, associate professor of animal and food sciences in UD’s College of Agriculture and Natural Resources, have identified gene expression irregularities at the onset of wooden breast syndrome that suggest the disease is a metabolic disorder characterized by abnormal fat accumulation in the breast muscle tissue.
The research team reported their results on Wednesday, Nov. 20 in the journal Scientific Reports.
The findings could help drive short-term solutions to help growers manage the condition in chickens at the production level through feed additives or supplements, or to reduce the number of birds that develop the condition.
“The industry desperately needs a solution right now. Conservative estimates project that wooden breast syndrome is costing the U.S. agricultural community $200 million dollars per year, but this number may be much higher,” said Abasht.
The United States leads production of broiler chickens worldwide. Delaware has more than 700 producers who raise commercial broiler chickens and over 1,000 small backyard poultry owners. Wooden breast syndrome is a concern around the world, too, as global consumption of chicken has risen in recent years as a leading source of dietary protein.
The research also could inform human health research related to metabolic syndromes, such as diabetes and atherosclerosis, which is associated with fatty deposits in the arteries.
Source of the problem
Abasht has been studying wooden breast syndrome in broiler chickens for nearly a decade. In previous work, his research team analyzed the genes involved in the disease and identified biomarkers for the disorder. They also characterized the unique biochemistry of the hardened breast tissue in chickens with the disease.
In their current work, the UD research team noticed that the expression of lipoprotein lipase was higher in chickens affected with wooden breast syndrome, leading more fat to accumulate in the chicken’s pectoral (or breast) muscles. Lipoprotein lipase serves as a “metabolic gatekeeper” that determines how much fat is allowed inside a given tissue.
This was curious because breast muscle fibers in chicken typically rely on sugar (glucose) molecules for fuel, not fat molecules.
The research team used RNA sequencing to determine which genes were being expressed in modern fast-growing broiler chickens and slower-growing legacy chickens. They then employed a new technology, called RNA in situ hybridization, to pinpoint exactly where this gene expression occurred inside the muscle.
The researchers found genetic evidence of lipoprotein lipase being expressed in endothelial cells in chickens, which was previously unknown. Present in all blood vessels, endothelial cells serve as a barrier between the blood and the surrounding tissue.
Abasht hypothesized that when more fat is oxidized for energy in the breast tissue of chickens, it may be causing the excessive release of free radical molecules that would modify (damage) fats and proteins in the muscle, prompting the chicken’s immune system to kick in to clear up the problem.
“We observed that if a particular vein was attacked by immune cells, the same vein typically also expressed higher levels of lipoprotein lipase,” said Abasht.
The researchers went a step further and compared this data with the gene expression signals found in two commercial broiler chicken lines, at three weeks of age and again at market age. In their analysis, the researchers found signals consistent with the fact that young chickens may be showing the same changes as market-age broiler chickens with wooden breast syndrome, even before the disease shows up.
The findings could provide potential markers to identify chickens that will develop the disease.
In recently published research in Genes, the researchers also reported finding common features between wooden breast syndrome in chickens and diabetes complications in humans, specifically diabetic cardiomyopathy, a chronic disease characterized by molecular and structural changes in the heart muscle.
Abasht’s research team is currently combing available literature for treating diabetes to see if there are ways to apply similar approaches to help broiler chickens avoid — or cope — with wooden breast syndrome, through diet, supplements or medication.
If they can find common solutions, Abasht said, a far-reaching goal of the work might be to use chickens as a model to study possible treatments for diabetes in humans.
“Our main focus was to address this problem from an agricultural perspective, but our findings open new horizons for future research that could benefit both agriculture and human health. This is a very interesting prospect for us,” said Abasht.
Longer term, Juniper Lake, a UD doctoral student in Abasht’s lab, said that having a deeper understanding of the genetic causes behind the disease could lead to solutions for agricultural producers to selectively breed out the traits that cause wooden breast disease, which has a relatively high heritability.
“There’s a lot to be gained from basic research of wooden breast, even if the main goal is to mitigate economic losses in the poultry industry,” said Lake.
With the Thanksgiving holiday just around the corner, it is important to note that wooden breast disease is currently only found in broiler chickens. It is not known to affect turkeys.
One Health Certified label seeks balanced approach to poultry production, marketing, By Don Ritter, DVM, director of technical marketing, Mountaire Farms
A new label under development for meat and poultry products will represent production that seeks a balanced approach to poultry production and marketing — one that ensures good health and welfare for the chickens while demonstrating responsible antibiotic usage under veterinary oversight to consumers, Don Ritter, DVM, director of technical marketing, Mountaire Farms, told Poultry Health Today.
Called One Health Certified, the new USDA Agricultural Marketing Service (USDA-AMS)-certified label is in part a response to arbitrary standards in production criteria, such as prohibiting the use of antibiotics to prevent, control or treat disease.
Ritter believes the supply chain from “no antibiotics ever” (NAE) production systems is not predictable nor sustainable. When the focus is only on never using antibiotics, the health of the animal suffers. There may be increased mortality. Those that survive require more feed and take longer to get to market, and the environment suffers too.
Okay but outdated
At the other end of the spectrum is what’s often referred to as “conventional” production, where veterinarians have the option of using all FDA-approved antibiotics for managing poultry diseases. This approach to production has declined in recent years as poultry companies have sought to meet increasing consumer demand for chickens raised without antibiotics.
The One Health Certified label advocates responsible use of antibiotics, where needed, while giving consumers an audited, transparent program built upon five core pillars: biosecurity, veterinary care, antibiotic stewardship, animal welfare and environmental measurements.
The program has “action thresholds,” which make it unique, Ritter continued. For instance, when the health status of an animal group changes, actions are required. If it’s a disease process, there has to be veterinary involvement within 24 hours, and animals are properly taken care of. Everything is documented.
There are similar but not identical guidelines for all species. “I see it as an umbrella program…over the multiple protein classes,” he said.
Sustainable, practical
Nothing will fall through the cracks in this system, Ritter maintained, but he acknowledged it will require poultry companies to provide documentation about production practices.
The program is intended to avoid extra costs for consumers and has options that make it sustainable and practical, Ritter said. Mandating extreme practices for the entire supply chain that raise the cost of food takes away choice from people who don’t have resources.
Consumer research with about 1,000 people has indicated that 83% would buy products with the One Health Certified label. Respondents said they most valued veterinary care and want animals taken care of, he said.
Saturated NAE market
Asked if the trend toward NAE production can ever be reversed, considering it now accounts for over 50% of the US poultry market, Ritter said, “To me, gravity is a very powerful force, and I really do think the pendulum swung a little too far…” when that much of production became NAE.
Even though over 50% of chickens are produced now in NAE systems, NAE chicken meat accounts for only 10% of pounds sold, Ritter noted. NAE producers are selling 20% of their meat labeled as NAE and they’re getting a premium, but the meat is more expensive because producers have to recover the cost of running that type of production system. That premium is being eroded as this segment of the market becomes saturated, he said.
One Health Certified, which has been designed by a coalition that includes animal agriculture, nonprofit groups and university scientists, will require education and supportive messaging. The goal is to get it through the USDA-AMS auditing process and launch a website. The certification will be open to any producer who follows the rules, Ritter said.