Invited review: Breeding and ethical perspectives on genetically modified and genome edited cattle

Abstract

The hot topic of genetic modification and genome editing is sometimes presented as a rapid solution to various problems in the field of animal breeding and genetics. These technologies hold potential for future use in agriculture but we need to be aware of difficulties in large-scale application and integration in breeding schemes. In this review, we discuss applications of both classical genetic modifications (GM) using vectors and genome editing in dairy cattle breeding. We use an interdisciplinary approach considering both ethical and animal breeding perspectives. Decisions on how to make use of these techniques need to be made based not only on what is possible, but on what is reasonable to do. Principles of animal integrity, naturalness, risk perception, and animal welfare issues are examples of ethically relevant factors to consider. These factors also influence public perception and decisions about regulations by authorities. We need to acknowledge that we lack complete understanding of the genetic background of complex traits. It may be difficult, therefore, to predict the full effect of certain modifications in large-scale breeding programs. We present 2 potential applications: genome editing to dispense with dehorning, and insertion of human genes in bovine genomes to improve udder health as an example of classical GM. Both of these cases could be seen as beneficial for animal welfare but they differ in other aspects. In the former case, a genetic variant already present within the species is introduced, whereas in the latter case, transgenic animals are generated-this difference may influence how society regards the applications. We underline that the use of GM, as well as genome editing, of farm animals such as cattle is not independent of the context, and should be considered as part of an entire process, including, for example, the assisted reproduction technology that needs to be used. We propose that breeding organizations and breeding companies should take an active role in ethical discussions about the use of these techniques and thereby signal to society that these questions are being responsibly addressed.

The ethics of genome editing in non-human animals: a systematic review of reasons reported in the academic literature

“…Many reasons in favour of genome editing in animals mentioned the efficiency of these techniques. First, it was argued that genome editing could be a potentially efficient and rapid tool to improve important traits in livestock [26,96,97], which could increase production efficiency [19,48,70,96,115,133,139], for example, by achieving a higher meat yield [19,48,70,96,139]. Various authors argued that genome editing using engineered nucleases (ZFN, TALEN or CRISPR) was more efficient, versatile, precise, easy to use or accurate than previous genetic technologies [3,4,6,7,9,33-35,37,40 -43,46, 49 -51,53,56,63,64,69,75,79,82 -84,98,105,110,114,126,129,131, 133,134,136,140,142].…”

“…For genome editing in general, the uncertainty involved in assessing potential consequences of genome editing technologies was stressed. It was argued that the risks or consequences of genome editing technologies could be difficult or even impossible to characterize beforehand, given their novel features [20,102,117,143] and our incomplete knowledge and understanding of the genetic background of complex traits [96]. With respect to applications of genome editing in animal farming, on the other hand, it was argued that genome editing could be considered similar to conventional breeding because the created modifications are comparable to natural mutations and no transgenes are involved [47,48,80,85].…”

Livestock breeding for the 21st century: the promise of the editing revolution

“…For many, issues related to technology do not elicit a yes or no response but a case-by-case deliberation. Reports of surveys of public opinion are starting to emerge [52][53][54] . These show general support for application of the technology, with a parallel cry for more information so that informed opinions can be developed [55] .…”

Genome Editing by Programmable Nucleases and their applications in livestock species

“…Cattle-Various genome-editing techniques have been used to date in cattle for specific gene modifications (Ericksson et al, 2017;Yum et al, 2018).Using CRISPR/Cas9 system NRAMP1 (natural resistance to infection with intracellular pathogens) gene was introduced in cattle giving resistance against Mycobacterium bovis which causes tuberculosis in these animals (Gao et al, 2017). SP110 gene has been introduced using TALEN in the intergenic region of macrophage of bovine making it resistant to M.bovis .…”