Wooden breast - a novel myopathy recognized in broiler chickens

Abnormally hard breast fillet consistency began to emerge in commercial broiler chickens around 2010. Due to the remarkable muscle hardness, the condition acquired the vernacular name wooden breast myopathy. This myopathy starts to develop after two weeks of age at the earliest and typically proceeds into chronic myodegeneration in three to four weeks of age. The lesion begins focally and typically develops into a diffuse lesion that involves the entire major pectoral muscle. The restricted location of wooden breast lesion in the m. pectoralis major distinguishes it from several other myodegenerative diseases that widely affect the skeletal muscle system and often the cardiac and smooth muscle systems too. Although industry-wide incidence rates are difficult to assess, it has been estimated that approximately 5-10% of commercially produced breast fillets exhibit severe WB. Even at low incidence rates, the costs to industry are substantial, as breast fillets with the wooden breast condition are often downgraded and sold at a discount, used for further processing, or in extreme cases, discarded. Because the etiology of wooden breast is still unclear, in the future, study of the early lesions, pathogenesis and the possible reduction of animal welfare are likely to gain more attention.