Prevalence of breast myopathies in broilers according to farming practices: an European survey

Over the past decade, breast muscle myopathies such as White Striping (WS), Wooden Breast (WB), and Spaghetti Meat (SM) have raised concerns about poultry meat quality and sustainability. This study assessed the prevalence and severity of these defects across six broiler farming systems differing in genetics, growth rate, slaughter weight, and access to outdoor areas. Between 2022 and 2023, 90 farms across Belgium, France, Italy, Poland, and Switzerland were sampled. For each farm, 50 breast fillets were visually scored for WS (0–2), WB (0–3), and SM (present/absent). Farm categories were: Indoor_Fast_Heavy (35 farms), Indoor_Fast (15), Indoor_Fast_Med (10), Outdoor_Fast_Heavy (5), Outdoor_Medium (15), and Outdoor_Slow (24). These groups reflect systems commonly used in Europe. The most severe myopathies were observed in Indoor_Fast_Heavy systems (Ross 308), with 44% of fillets showing WB, including 11.8% with severe lesions (score 2 or 3). In contrast, the same genotype raised in Outdoor_Fast_Heavy systems showed significantly lower WB rates (14%, with 2.1% severe cases), suggesting the benefit of reduced dietary density, a sex effect, and outdoor access. Slower-growing genotypes also had reduced myopathy prevalence: WB rates were 51% and 34% in Indoor_Fast_Med and Outdoor_Medium, respectively, with severe cases of 3.8% and 0.2%. SM was found in 9.7% of Indoor_Fast_Heavy fillets, but only 0.4% in Outdoor_Fast_Heavy. A subset of farms (one per category, excluding Outdoor_Fast_Heavy) was selected for MYH15 analysis, a muscle regeneration biomarker. MYH15 expression was quantified on homogenized muscle samples. Higher expression levels were associated with fillets showing more severe myopathies, particularly in intensive systems, confirming its potential as a diagnostic marker. ANOVA and Kruskal-Wallis tests were applied to compare myopathy scores across systems. Correlation tests and Random Forest analysis are ongoing to assess the relative impact of production practices and guide recommendations. Early results highlight the strong link between fast growth and myopathy risk, and the potential of alternative systems to reduce defect incidence.