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The syndrome known as woody breast and white striping in broiler chickens has emerged in recent years as a worldwide problem for which the exact causes are unknown, but extensive scientific research is now yielding clues about how to reduce its incidence and severity.
Dr. Tara York, technical manager for AB Vista, speaking at the 2017 Poultry Nutrition & Milling Seminar, presented a survey of promising research about possible causes and reduction strategies for white striping. The research centered on the following woody breast management and nutritional strategies:
A normal chicken breast fillet, free of woody breast/white striping. | Dr. Abit Moray, Auburn University
Myopathies associated with woody breast/white striping are apparent to poultry processors, further processors and consumers, alike. White striping involves a visible deposition of fat and fibrous tissue between muscle fibers. Woody/wooden chicken breasts are firm to hard breast meat that may have a prominent ridge down its length. The breast meat may also have a pale color, soft consistency and poor water holding capacity.
The economic impact of woody breast and white striping in chicken breast meat in the U.S. is considerable, York estimates, and could cost the broiler industry more than $200 million per year due to decreased yield (trimming, drip loss, cook loss, etc.) or more if product is discarded. That’s not including the indirect costs of the negative impacts on customer acceptance and consumer satisfaction due to the hardening and striping of the breast meat.
With U.S. broiler production at 53 billion pounds (live weight) of chicken per year and 23 percent breast meat yield, she calculates the number of pounds of chicken breast meat at risk for the myopathies is 12 billion pounds annually. While the actual percentage of product affected by the woody breast/white striping condition is undetermined, the impacts are experienced by both the broiler industry and its customers.
“While a customer perception nightmare, woody breast is still a wholesome product,” York said. However, woody breast meat is being diverted in some cases to less-than-premium uses, including as an ingredient in pet food.
Poultry further processors are seeking answers not only to the hardened texture but the meat’s decreased water-holding capacity.
In other cases, food processors are complaining that the hardened chicken breasts dull their cutting equipment.
“The reality is that the impact is being felt across the broiler industry, including in the processing plants where the sorting to divert woody breasts is costing time and money,” she added.
The highly-publicized move by one fast-food chain to begin sourcing its chicken breasts only from smaller, lighter-weight broilers highlights the fact that woody breast/white striping occurs mostly in fast-growing, heavier broilers.
“Unfortunately, genetics is taking the brunt of the blame for woody breast and white striping at this point,” York said, “though we really don’t know what is causing it.”
In trying to appeal to consumers, reports show fast-food chains like Wendy's are pledging to source meat from smaller birds.
Nonetheless, the woody breast problem has come full circle, she continued, with much research focused on nutritional and management aspects that promise to reduce its incidence and severity.
The reduction of amino acids in broiler diets is a way to slow the animal’s growth rate and possibly reduce the incidence and severity of woody breast and white striping.
York cited Auburn University research that reduced one amino acid, lysine, to 85 percent, or 75 percent of requirements during the growing period (either from 12 to 18 days or 19 to 26 days). The study found no impact on body weight gain, feed conversion, feed intake or mortality, but a reduction in the incidence/severity of woody breast for the 75 percent reduction compared to the positive control.
She indicated some – but not all – broiler producers who have fed reduced levels of lysine have had success in reducing the incidence and severity of woody breast and white striping.
Similarly, a study at Texas A&M showed a reduction in the severity of woody breast when all amino acids were reduced by about 15 percent during the growing phase.
Oxidative stress is a possible trigger for woody breast and white striping in broilers.
York posed the question: “Is the broiler receiving all the metabolic support it need as it grows to heavier weights?”
Research in the U.S. and Italy has investigated the value of super-dosing antioxidants in growing rations to reduce potential myopathies in the muscle tissue. Feeding higher levels of vitamin E, copper, zinc, manganese, selenium, iron and possibly other minerals is a “defensive play” that may be effective in the reduction of woody breast, particularly in maintaining this nutrition as broilers get older.
In an early study, Italian researchers achieved a reduction in the overall severity of woody breast when two levels of phytase and inositol were super-dosed to 49 days of age. A field study by AB Vista that fed broilers ethoxyquin and organic selenium achieved similar reductions in the severity of woody breast.
The most effective super-dosing strategies, York said, have fed multiple antioxidants in the grower diet, including ethoxyquin, zinc, selenium and iron – what she refers to as the “kitchen sink” approach.
“It is not until everything is combined in the feed formulation treatment that weight gains were achieved without the most severe form of woody breast," she said.
York speculated that a combination of super-dosing with antioxidants and reducing amino acid levels might be effective in reducing woody breast conditions while achieving desired breast meat yields.
The feasibility of such an approach, she said, depends upon how big of an issue woody breast is for a broiler operation.
The 2017 Poultry Nutrition & Milling Seminar was cosponsored by the Alabama Feed & Grain Association and the World’s Poultry Science Association.