Role of muscle satellite cells in the Wooden Breast broiler chicken meat quality defect
Type of DegreePhD Dissertation
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The poultry industry has made improvements in nutrition, genetic selection, and management to improve broiler chicken growth performance and breast meat yield. However, these observed increases in performance have been correlated with the increased incidence and severity of a meat quality defect known as Wooden Breast (WB). Due to its poor meat quality traits, WB has caused large economic losses to the poultry industry and extensive research has been conducted to understand the cellular and molecular mechanisms of WB. Even though the etiology of WB remains unknown, many speculate that the impaired function of muscle satellite cell (SC) may contribute to the development of WB as these cells function in muscle growth and repair. Protein expression data revealed increased protein abundance of paired box 7 (Pax7) and myogenin and decreased abundance of myogenic differentiation factor 1 (MyoD) myogenic regulatory factor (MRF) expression in WB-affected muscle tissue compared with normal indicating SC dysfunction in WB-affected tissue. Two starter diets nutrient reduction experiments were then conducted to generate a model to reliably generate WB-affected and unaffected muscle samples by slowing broiler body weight gain (BWG) and decreasing body weight (BW). Broilers fed a starter diet with a 10% targeted reduction in digestible lysine (dLys) and metabolizable energy (ME) were able to overcome the nutrient reduction by increasing their food intake (FI) resulting in similar BW compared with broilers fed a control starter diet. However, when broilers were fed a starter diet with a 30% targeted reduction in dLys, digestible methionine, and ME combined offered in meal form were not able to overcome the nutrient restriction, gained less weight, and exhibited less incidence of WB compared with birds fed a control starter diet in crumble form. A final study was conducted where birds were fed a control starter diet in crumble form or a nutrient reduced diet in meal form to generate muscle samples to assess collagen infiltration, macrophage population heterogeneity, and SC population MRF heterogeneity. Collagen infiltration and the macrophage population heterogeneity of total, pro-inflammatory, and anti-inflammatory macrophages were not different between treatment groups. However, SC population heterogeneity differences were observed among treatments. Together, further research is warranted to better understand the role of SC in WB.