Detection of differentially expressed genes in broiler Pectoralis major muscle affected by White Striping – Wooden Breast myopathies

White Striping and Wooden Breast (WS/WB) are abnormalities increasingly occurring in the fillets of high breast yield and growth rate chicken hybrids. These defects lead to consistent economic losses for poultry meat industry, as affected broilers fillets present an impaired visual appearance that negatively affects consumers’ acceptability. Previous studies have highlighted in affected fillets a deeply damaged muscle, showing profound inflammation, fibrosis and lipidosis. The present study investigated the differentially expressed genes and pathways linked to the compositional changes observed in WS/WB breast muscles, in order to outline a more complete framework of the gene networks related to the occurrence of this complex pathological picture. The biochemical composition was performed on 20 Pectoralis major samples obtained from high breast yield and growth rate broilers (10 affected vs. 10 normal) and 12 out of the 20 samples were used for the microarray gene expression profiling (6 affected vs. 6 normal). The obtained results indicate strong changes in muscle mineral composition, coupled to an increased deposition of fat. In addition, 204 differentially expressed genes (DEG) were found: 102 up-regulated and 102 down-regulated in affected breasts. The gene expression pathways found more altered in WS/WB muscles are those related to muscle development, polysaccharide metabolic processes, proteoglycans synthesis, inflammation and calcium signaling pathway. On the whole, the findings suggest that a multifactorial and complex etiology is associated with the occurrence of WS/WB muscle abnormalities, contributing to further define the transcription patterns associated to these myopathies. Broiler of the same genetic type and reared on the same flock were inspected at slaughterhouse to identfy 6 fillets with normal phenotype (NORM) and 6 fillets with white striping / wooden breast myopathy (ABN). The average transcription profile of the ABN animals wase comapred with that of the NORM broilers in order to detect differentially expressed genes.