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367 Role of skeletal muscle satellite cells in the broiler chicken Wooden Breast myopathy


 To meet the huge global demand for chicken meat, the commercial broiler industry has placed tremendous genetic selection pressure on breast meat yield, growth rate, and feed efficiency traits and has made remarkable improvements over the last 30 years. Unfortunately, along with those tremendous improvements has come a severe meat quality defect whose cause has yet to be elucidated. The Wooden (or Woody) Breast (WB) meat quality defect is characterized by visible bulging of the breast fillet with extreme hardness to the touch. The WB phenotype has been characterized by histopathologists as a degenerative myopathy in which excessive fibrotic tissue infiltration occurs. Skeletal muscle stem cells, also called satellite cells (MSC), play a critical role in post-hatch broiler skeletal muscle growth, repair, and maintenance. Yet the relationship between MSC function in high-yielding broilers and the development of the WB myopathy is still not well understood. Recent work using in vivo cell labeling, cryohistology, and immunofluorescence techniques demonstrates that the relative size and mitotic activity of the various MSC and macrophage populations and collagen deposition are altered in WB-affected muscle. Alterations in myogenic regulatory factor, collagen, and pro- and anti-inflammatory cytokine protein expression in WB-affected muscles have also been observed using quantitative fluorescent Western blotting. These data suggest the involvement of aberrant MSC function in the development of WB myopathy. Future work aimed at determining whether the apparent MSC dysfunction in WB-affected broilers is due to an issue with the MSC themselves and/or their environment will be accomplished using a combination of MSC isolation, labeling, transplant, and tracking strategies. Further exploration will also be required to understand how the local cell signaling mechanisms and cell population kinetics are related to the severity and timing of the development of the WB myopathy in today’s fast-growing, high-yielding broilers.