Characterizing Differential Pectoralis Muscle Production and Gene Expression Between Modern and Heritage Gallus Broiler Lines

The advent of industrial agriculture has resulted in intensive selection for rapid overall and, especially, pectoralis muscle growth in the broiler chicken.  The pectoralis muscles are the primary source of broiler meat production and are of critical agricultural and economic interest.  Comparative studies using representative “modern” and “heritage” broilers provide an excellent vehicle for understanding the changes in broiler traits, both intended and unintended, that have resulted from this human-directed evolution.  In addition, recent improvements in next-generation sequencing technologies provide a tremendous opportunity to potentially identify specific target genes to aid in the future improvement and protection of this important food source.  This study utilized the Ross 708 line as a representative modern broiler and the University of Illinois Heritage line to represent broilers as they grew in the 1950s.  Prior research has indicated that, between these two lines, an important divergence in pectoralis growth pattern occurs around post-hatch day 14.  Transcriptome libraries were generated from modern and heritage pectoralis muscle both before and after the critical D14 time-point using RNA-seq.  This comparison of pectoralis gene expression levels between the two lines has revealed differential enrichment of genes affecting cell proliferation, the extracellular matrix, lipid and carbohydrate metabolism, calcium handling, and other factors related to skeletal muscle growth and development.