45 Genome Editing of Livestock for Production Agriculture and Biomedical Applications

Abstract

Abstract Continued population growth and clear evidence of climate change are placing unprecedented strain on food production and health care systems worldwide. Agricultural production goals that highlight environmental sustainability are at the forefront of social dialog, with animal agriculture routinely targeted for inefficiencies, welfare concerns and impact on climate. Genomic selection has transformed animal production and the rate of genetic gain in each generation continues to increase. Nonetheless, it is apparent that the rate of production gains will fall short of the necessary goals of increased efficiency and adaptation to the changing environment. Genetic engineering may have an important role in enhancing livestock production as well as providing new models for research in human health. The CRISPR/Cas and related systems for targeted gene editing has revolutionized livestock genetic engineering by increasing the rate of targeted mutation, thus drastically reducing the cost of producing founder animals with the desired trait. Intentional insertion of well-known mutations into genes such as myostatin have been shown to impart the expected increase in meat production, but have also resulted in undesirable associated traits affecting fertility, marbling and the skeleton. Thus, the approach to increasing meat production may require nuances such as promotor targeting and multiple gene targeting to obtain the desired production characteristics. Efforts to increase disease resistance could have dramatic impacts on animal welfare and production rates, potentially saving millions of animals from morbidity and mortality. However, confronting a single disease with each genetic alteration will be costly and inefficient. Considerations on how broad scale disease resistance could be achieved through genetic engineering will be instrumental in developing livestock with advantages to avoid infection and/or transmission of multiple pathogens. Gene editing also allows correction of mutations that arise in livestock through natural mechanisms while under intense genomic selection for increased production. Removing disease causing mutations in otherwise high value livestock will allow continued production from these lines without concern for inheriting the causative mutation. The same process can be utilized to insert genetic mutations known to phenocopy human conditions providing valuable large animal models of human genetic disease. Increased milk, meat, or eggs per animal unit will sustainably improve high quality, nutrient dense food production while large animal models of human disease will provide a more translational biomedical model for accelerated development of drugs and treatments. These goals are achievable, but require continued investment in innovation, clear regulatory framework for commercialization, education, and public engagement to ensure success.