The human population is growing, and as a result we need to produce more food whilst reducing the impact of farming on the environment. Selective breeding and genomic selection have had a transformational impact on livestock productivity, and now transgenic and genome-editing technologies offer exciting opportunities for the production of fitter, healthier and more-productive livestock. Here, we review recent progress in the application of genome editing to farmed animal species and discuss the potential impact on our ability to produce food.

Many technologies, at the time of their inception, have appeared efficacious, safe, and generally a good idea, based on the science at the time. However, in a number of cases, a technology that was once deemed appropriate and desirable has later turned out to be not such a good idea after all. Not only has it failed to deliver on its promises, but it has given rise to environmental damage and negative health impacts. Such technologies have ended up being abandoned or tightly restricted.

There are many examples from history. Asbestos, DDT insecticides, leaded gasoline, and PCBs (polychlorinated biphenyls) in electrical goods were all once hailed as great innovations, but as we grew in our understanding of the mechanisms and complexities of nature’s functioning, we found they could have devastating effects on the health of humans and animals.

We continue to learn from our catastrophic mistakes, but only after serious damage has already occurred to health and the environment. In order to avoid such damage, we need to constantly review each technology from the perspective of the science from which it is derived. Transgenic and genome editing technologies are no exception.

Plant breeding is a developing process and breeding methods have continuously evolved over time. In recent years, genome editing techniques such as clustered regularly interspaced short palindromic repeats/CRISPR associated proteins (CRISPR/Cas), transcription activator-like effector nucleases (TALENs), zinc-finger nucleases (ZFN), meganucleases (MN) and oligonucleotide-directed mutagenesis (ODM) enabled a precise modification of DNA sequences in plants. Genome editing has already been applied in a wide range of plant species due to its simplicity, time saving and cost-effective application compared to earlier breeding techniques including classical mutagenesis. Although genome editing techniques induce much less unintended modifications in the genome (off-target effects) compared to classical mutagenesis techniques, off-target effects are a prominent point of criticism as they might cause genomic instability, cytotoxicity and cell death.