ABSTRACT
Molecular breeding techniques to improve egg quality Anna Wolc, Iowa State University, and Hy-Line International, USA; and Janet E. Fulton, Hy-line International, USA
1 Introduction
2 Whole-genome methods to improve egg quality
3 Improving external egg quality
4 Improving internal egg quality
5 Genomic selection
6 Targeting candidate genes for particular traits
7 Gene expression and regulation
8 Summary and future trends
9 Where to look for further information
10 References
Since the release of the chicken genome sequence in 2004 (Hillier et al., 2004), the tool box available for genetic improvement of the multiple traits that define egg quality has improved tremendously. That initial sequence has been revised and improved several times with Gallus_gallus-4.0 now available in multiple publicly accessible websites. An improved Gallus_gallus-5.0 version is soon to be released. Genome sequence comparisons between mammalian and avian species have allowed for the identification and subsequent annotation of genes, and initiated the understanding of the functions of the genes and the interdependent relationships between the thousands of genes that comprise multicellular organisms. The recent sequencing of multiple breeds of chickens, both research and commercially utilized lines, revealed the presence of millions of genetic variants and resulted in the development of a commercially available chip that can simultaneously query 600 000 single DNA base sequence variants (Kranis et al., 2013). Numerous methodologies are now available that allow for detection of gene expression in specific tissues or relative gene expression between different treatments or individuals (Rapaport et al., 2013). To aid in the analysis of the large amounts of genetic information that is generated, various computer programmes have been developed that allow for the integration and eventual application of this information into a breeding programme (Wolc et al., 2016).
