Effects of Aging on Muscle Development Based on Transcriptome Sequencing in Dahen Broilers

Skeletal muscle growth and development represent a pivotal biological process that determines both the yield and quality of poultry meat. As chickens age, there is an observable shift in their muscle structure, function and metabolic properties. However, the molecular mechanisms by which age regulates chicken muscle development and meat quality formation are not yet fully understood. The objective of this study was to elucidate the fundamental molecular mechanisms through which the aging process influences the development of chicken muscle and the quality of meat. A total of 20 female Dahen chickens, comprising 10 birds at 3 months of age and 10 at 72 months of age, were subjected to systematic measurements of meat quality indexes and muscle fiber characteristics. From each age group, 3 out of the 10 birds were randomly selected for breast muscle transcriptome analysis. The results demonstrated that aged chicken breast muscle exhibited reduced tenderness, augmented intramuscular fat content and water-holding capacity, while muscle fibers demonstrated significant hypertrophy and reduced density. A total of 819 differentially expressed genes (DEGs) were identified by RNA-seq, which were predominantly enriched in the biological processes of muscle system process, muscle organ development, and skeletal muscle cell differentiation, and were involved in the pathways of cytoskeleton in muscle cells, and extracellular matrix (ECM)-receptor interaction signaling, among others. The expression of key genes, such as COL1A2, THBS2, FN1, and MYBPC1, was found to be significantly altered, a finding that was verified by qPCR in agreement with the sequencing results. The study demonstrated that age impacts meat quality traits by inducing muscle fiber hypertrophy, ECM remodeling and metabolic reprogramming. The related genes provide a valuable reference point for understanding the genetic regulation of avian muscle development and meat quality.