Genome editing of avian species: implications for animal use and welfare.

Avian species are used as model systems in research and have contributed to ground-breaking concepts in developmental biology, immunology, genetics, virology, cancer and cell biology. The chicken in particular is an important research model and an agricultural animal as a major contributor to animal protein resources for the global population. The development of genome editing methods, including CRISPR/Cas9, to mediate germline engineering of the avian genome will have important applications in biomedical, agricultural and biotechnological activities. Notably, these precise genome editing tools have the potential to enhance avian health and productivity by identifying and validating beneficial genetic variants in bird populations. Here, we present a concise description of the existing methods and current applications of the genome editing tools in bird species, focused on chickens, with attention on animal use and welfare issues for each of the techniques presented.