Evaluation of genetic factors involved in the onset of breast muscle abnormalities affecting fast-growing chickens

To meet the increasing consumer demand for chicken meat, poultry companies implemented intensive breeding programs to improve the productive performances of modern broilers, which indirectly led to the occurrence of muscular abnormalities, namely white striping (WS) and wooden breast (WB) defects. Despite the enormous progress in understanding their primary causes, the precise etiology remains to be clarified. This dissertation aimed at providing new insight on the underlying mechanisms of these abnormalities by implementing different approaches of gene and protein expression analysis. Since the central hypothesis was the differing gene and protein expression profiles of breast muscles affected and unaffected by these defects, the studies dealt with i) investigation of patterns of co-expressed genes associated with the phenotypic traits significantly related to the onset of WS and WB; ii) gene and protein expression analyses of key factors likely involved in the manifestation of these defects by looking at multiple steps of muscle development of broilers selected for different growth rates; and iii) characterization of WB muscles by performing a differential gene expression analysis. The results strengthened the evidence of a complex etiology of these myopathies and put forward molecular and cellular key players potentially involved in the WS and WB onset, such as one of the major extracellular matrix components: the Collagen type IV. Also, genes potentially involved in the molecular alterations characterizing these abnormalities were found, e.g. the peroxisome proliferator-activated receptor co-activator 1 (PCG1) alpha and beta, and the fibro-adipogenic progenitors (FAPs). The outcomes of this thesis also corroborated that vimentin and desmin can be considered potential markers of the regenerative processes occurring in abnormal breast muscles. Overall, these achievements may be useful to reduce the incidence of breast myopathies in broilers by identifying biomarkers likely suitable to exclude broilers prone to develop WS and WB from breeding practices.