Review links broiler muscle growth gains to myopathy risk

A new review in Animals examines a familiar tension in modern broiler production: the same selection and nutrition strategies that helped birds grow faster and produce more breast meat have also been linked to a rise in muscle abnormalities such as wooden breast, white striping, and spaghetti meat. The authors, Md Raihanul Hoque, Casey Owens, and Craig Coon, synthesize current evidence on muscle fiber growth, pathology, detection, and mitigation, positioning these myopathies as a byproduct of production systems optimized for rapid growth and high breast yield. (mdpi.com)

That framing fits a broader body of literature. Reviews and industry papers over the past several years have described how modern broilers rely heavily on post-hatch muscle fiber hypertrophy, with breast muscle enlarging faster than supporting connective tissue, circulation, and repair mechanisms can always accommodate. Casey Owens wrote in an industry presentation that broiler weights roughly quadrupled from 1957 to 2005, while breast meat yield increased by about 80%, and she described white striping and woody breast as serious economic issues in heavier, fast-growing birds, particularly high-breast-yield strains. (midwestpoultry.com)

The pathology is now better described than it was a decade ago, even if the full causal chain is still unresolved. White striping is characterized by fat deposition running parallel to muscle fibers, while wooden breast is marked by abnormal hardness and fibrosis, and spaghetti meat by fiber separation and poor structural integrity. Histologic and biochemical studies have linked these defects to myofiber degeneration, inflammatory cell infiltration, altered metabolism, connective tissue remodeling, and collagen changes. One recent review noted that white striping has become common to “almost all” broilers, while another paper reported prior work showing incidence in chicken breast products can be very high, though severity varies and severe cases are less common. (mdpi.com)

Industry and academic researchers have also tried to sort out how much of the problem is genetic and how much is environmental or managerial. An Aviagen paper published in 2026 says the heritability estimates for these breast muscle myopathies are generally low to moderate, suggesting non-genetic factors still play a major role. That same paper says the poultry sector has spent the last decade refocusing on breast muscle myopathies as reports increased across commercial broiler strains, and it points to management recommendations alongside breeding work. A recent welfare review likewise found lower levels of white striping and wooden breast in an intermediate-growing genotype than in several fast-growing lines, reinforcing the link between growth intensity and muscle defects. (aviagen.com)

Expert and industry commentary has been fairly consistent on two points. First, these conditions are economically important because they reduce processability, increase downgrades, and can hurt consumer acceptance. Second, they are not generally treated as a direct public health hazard. A 2024 transcriptomic study in Animals states that spaghetti meat and woody breast do not constitute a public health concern, but can reduce processability through higher moisture loss and other quality changes. USDA ARS has similarly reported that wooden breast, white striping, and spaghetti meat alter water-holding behavior, with wooden breast in particular affecting muscle water retention and resistance to external force. (mdpi.com)

Why it matters: For veterinarians and poultry health teams, this review matters because it pulls a meat quality issue back into the larger conversation about bird biology, welfare, and production system design. These myopathies may show up at the processing plant, but their roots are on-farm and in the breeding pipeline: growth rate, breast yield, muscle fiber enlargement, oxygen demand, inflammation, and repair. That makes them relevant not only to processors and live production managers, but also to veterinarians advising on genotype choice, nutrition programs, stocking density, ventilation, bird activity, and flock monitoring. The practical takeaway is that there still doesn’t appear to be a single intervention that solves the problem; mitigation remains incremental and system-wide. (mdpi.com)

The review also underscores a growing operational challenge: as these defects become more familiar, detection and sorting matter more. Researchers are continuing to study physical, color, texture, and metabolomic markers that could improve classification of affected fillets and help plants manage product flow. That matters for veterinarians because the pressure to reduce incidence is likely to increase as integrators try to balance carcass yield, welfare expectations, and downstream quality performance. (mdpi.com)

What to watch: The next phase will likely center on whether breeding companies, integrators, and nutrition teams can reduce myopathy risk without materially sacrificing growth efficiency, and whether better in-line detection tools can turn a chronic quality problem into a more manageable one. Watch for more genotype-comparison studies, nutrition trials, and processor-side detection research over the next 12 to 24 months. (aviagen.com)