Looking deeper
Since no one will be able to fix the condition until the cause is known, the investigation continues – and with it comes research.
In addition to those in academia, geneticists, veterinarians and animal scientists throughout the industry, including those at processing and breeding companies, are investigating the woody breast condition.
“The exact cause is not known, so industry has embarked on research to determine the exact causes as well as possible solutions to this quality issue,” says Tom Super, senior vice president of communications for the National Chicken Council, Washington, DC.
Researchers throughout the poultry industry are joining the challenge.
“As a primary breeding company, we are looked to as a leader and are expected to assist in finding solutions to this type of problem,” Fancher says. “We have implemented selection strategies to reduce the genetic susceptibility to the condition, but are also working diligently to identify nutritional and management strategies which reduce the incidence and severity of the condition.”
“There are some very good hypotheses out there, but it’s still early on,” says Casey Owens-Hanning, Ph.D., associate professor in the Poultry Science Dept. at the Univ. of Arkansas.
USPOULTRY funded four separate research studies at independent universities and at the US Dept. of Agriculture’s Agriculture Research Service (USDA-ARS). The studies, costing approximately $250,000, are investigating potential causes for the condition, as well as a research study looking at ways to make it easier for processors to identify affected tissue.
“They’re [researchers] all looking at it from different areas which is what you have to do when there’s an unknown,” Glisson says.
Three of the USPOULTRY studies are focused on what’s causing the condition. An $80,000 study at North Carolina State Univ. is examining at which age the condition is occurring in chickens. Another North Carolina State Univ. study, costing $86,000, is focusing on nutrition. Researchers are specifically looking at the effect of the amino acids glutamine and arginine to determine if there are deficiencies, and if so, how that could affect the animals’ muscle development. The Univ. of Delaware is conducting a $58,000 study to examine the genetic expression of the condition.
Aviagen is also using its resources to help find a solution to the issue. “We have implemented a genetic selection strategy which involves scoring of meat quality in the processing plant to identify families that are more susceptible to the condition combined with some indirect measures on selection candidates that allow us to identify birds with the condition while they are still alive,” Emmerson says. “These indirect measures provide a very accurate way to identify individuals that have the condition and are very accurate predictors of the underlying changes in muscle structure that cause woody breast. This strategy will ultimately result in a reduction of woody breast in the production sector over the coming years.
“Additionally, we continue to conduct a lot of research investigating management and nutritional strategies that ameliorate the incidence of woody breast and are working with customers to get them implemented on a commercial scale.”
Emmerson explains that the theories as to why the condition is occurring fall into one of three lines of thought.
1. Identification of causes to the initial damage to the muscle tissue.
2. Determination of which factors interfere with normal muscle repair.
3. Determination of what can be done to provide the birds with better protection against developing the condition.
According to Emmerson: “One factor that is consistently shown to be important is the focus on optimizing nutrition and management during late incubation and the first 12-14 days of life. This life-stage period is critical for satellite cell development. Satellite cells play a key role in muscle growth and repair. We consistently find that if we do anything that compromises early growth and development, it can result in an increased incidence and severity of not only woody breast but also breast muscle striping.”
Breast muscle striping is another chicken muscle abnormality in which breast tissue is found with varying degrees of striations, parallel to the muscle fibers.
There has been speculation that the condition is more prevalent in larger broilers. Average bird weights are just over 6 lbs., but the big-bird segment is seeing average weights of up to 10 lbs. Some are concerned that the rapid growth of the birds could be causing a change in their muscle tissue.
Fancher responds to this theory saying, “While this is a widely held perception, the exact relationship between growth rate and the incidence of woody breast is quite complex. The genetic correlation between growth rate and woody breast is negligible – which means that there is no trade-off between these traits and we can reduce the incidence of woody breast without reducing growth rate per se.”
According to Aviagen researchers, the first 12-14 days of life are crucial to the muscle repair processes. “After this life-stage period, we have found that if we reduce the rate of muscle growth during the age period between 14 and 35 days we can significantly reduce the incidence and severity of both woody breast and breast muscle striping later in life,” Fancher says. “This means that the shape of the broiler growth curve is much more important than the growth rate per se. This is a practical approach which can provide some help for companies experiencing the problem.”
Product Segregation
Investigations continue throughout the industry, but the question remains – what to do with the meat that’s in production right now?
“Everyone’s coming at it from a different angle to figure it out, but the processors are left now trying to figure out what to do with the product when they come upon it,” says Shelly McKee, Ph.D., director of technical services with USPOULTRY.
Without an objective detection method in place, processors must rely on subjective tactile evaluation by quality assurance personnel to determine if there are affected fillets, so those products can be segregated from the rest.
With this in mind, USPOULTRY helped fund an additional research project that investigated possible ways to use imaging technology to detect the woody breast condition. Results from the study, “Identification of the Wooden Breast Condition in Broiler Breast Fillets Using Imaging Technology,” funded in part by $11,500 from USPOULTRY, and an endowment by GNP Company, St. Cloud, Minnesota, were released Aug. 19. The objective of the study, led by Brian Bowker, Ph.D., at USDA-ARS’s National Poultry Research Center in Athens, Georgia, was “to determine the feasibility of utilizing imaging-based technologies to rapidly and non-destructively detect the presence and severity of the WB condition in boneless, skinless broiler breast fillets.”
In this study, researchers used various imaging technologies to attempt to differentiate between the muscle surface characteristics of normal fillets and those affected with woody breast. Study results concluded that imaging analysis could distinguish between fat, muscle and connective tissue in breast fillets. Breast fillets in the study could be categorized as having woody breast with more than 95 percent accuracy.
“These results point to the feasibility of adapting imaging technology to detect wooden breast in an online processing plant setting,” according to USPOULTRY. “The development of such imaging technologies for detecting the WB condition would allow processors to more easily and accurately segregate product based on quality and uniformity.”
The next step, Glisson says, would be for an imaging company to design specific equipment that could go into a commercial setting.
“For decades, the chicken industry has evolved to not only meet ever-changing consumer needs and preferences, but to collaborate on issues like food safety, food quality and animal welfare for the betterment of the industry, our customers and their consumers,” NCC’s Super says. “Tackling this muscle condition head on is one recent example of collaboration between processors, geneticists, government and academia in an effort to continue our record of improvement by identifying the cause of this muscle condition and eliminating it as soon as possible. We’re confident the research underway will lead us to that goal.”
