Systems level investigation of the genetic basis of bovine muscle growth and development

Skeletal muscle growth is an economically and biologically important trait for livestock raised for meat production. As such, there is great interest in understanding the underlying genomic architecture influencing muscle growth and development. In spite of this, relatively little is known about the genes or biological processes regulating bovine muscle growth. In this thesis, several approaches were undertaken in order to elucidate some of the mechanisms which may be controlling bovine muscle growth and development. The first objective of this thesis was the development of a novel software tool (SNPdat) for the rapid and comprehensive annotation of SNP data for any organism with a draft sequence and annotation. SNPdat was subsequently utilised in chapters 3 and 6 to facilitate the identification of candidate genes and regions involved in bovine muscle growth. In chapter 4, a number of metrics were explored for their usefulness in assessing convergence of a Markov Chain using a Bayesian approach used in genetic prediction. The need to adequately assess convergence using multiple metrics is addressed and recommendations put forward. These recommendations were then implemented in chapter 3. In addition, three separate investigations of bovine muscle growth and development were performed. In chapter 3, a genome-wide association study was performed to identify regions of the bovine genome associated with four economically important carcass traits. This was followed by an examination of the transcriptional responses in muscle tissue of animals undergoing dietary restriction and compensatory growth (chapter 5). Finally, using high-throughput DNA sequencing, a candidate list of 200 genes was interrogated to identify genes which may be evolving at different rates, and under evolutionary selection pressure, in beef compared to dairy animals (chapter 6). A number of genes and biological pathways were found to be involved in traits related to bovine muscle growth, several of which were identified in more than one study