Environmentally-friendly, but dead

December 2017

In 1999, biotech boffins in Canada invented the 'Enviropig' genetically transformed to digest grain-based feedstuffs which pigs don't naturally eat, but which are now part-and-parcel of modern intensive pig-rearing [1].

This piggy-wonder was touted as being cheaper and greener to produce because, thanks to its novel digestive system, it wouldn't excrete huge amounts of polluting phosphates, and wouldn't smell. 'Environmentally-friendly' is always a good PR hand to play.

A hopeful herd of Enviropigs was maintained for 17 years, waiting for the market to want to eat them.

The pigs are all dead now. Total disaster. No customers. All cost and no return.

Not one pig-buyer has said yes to GM, some aren't sure, most say no. Their biggest fear is a fall in demand for pork, or the huge cost in certifying their wares GM-free.

There is, of course, another herd novel pigs in the pipeline, now 'gene-edited' rather than good old-fashioned GM [2]. Millions of dollars are being ploughed into gene-edited swine resistant to 'Porcine Reproductive and Respiratory Syndrome' (PRRS). Once called simply 'mystery swine disease', this piggy problem seems to be caused by a virus which infects the cells of the immune system itself and can manifest as coughs or even pneumonia, stillbirths or very weak piglets. The clinical picture is, however, far from clear: there may be no recognisable symptoms at all, or very severe disease leading to death, or anything in-between.

It's been suggested that the virus is unstable, mutating as it multiplies inside the pig and throwing up some strains that are virulent and some that are benign. With this level of uncertainty and variation which could equally be pig-based, pathogen-based or a bit of both, it's difficult to see how a man-made change in DNA is going to be anything but a shot in the dark.

Gene-editing which is touted as making precise changes at specific locations in the genome is claimed to be so safe and predictable that it doesn't even need to be regulated. However three teams of scientists have published papers during 2017 detailing widespread unexpected mutations, deletions and insertions in the DNA of gene-edited animals or cultured cells (see [3]).


Attempts are afoot to brand gene-edited organisms as somehow safer and more natural than old-fashioned GMOs with their inserted artificial DNA. However, the disruption to the healthy functioning of the genome is just as great. Realistically, the most likely 'success' story will be a PRRS-free GM herd which dies of some other familiar or unfamiliar swine disease.


[1] P-FREE PIGS IN THE PIPELINE - January 2011
[2] CRISPR/Cas9 GENE EDITING - March 2016
[3] ERRORS IN CRISPR - November 2017


  • Jim Long, Gene edited pork, will anyone buy?, 7.09.17 
  • Haiwei Mou, et al., 2017, CRISPR/Cas9-mediated genome editing induces exon skipping by alternative splicing or exon deletion, Genome Biology 18 
  • Ha Youn Shin, et al., May 2017, CRISPR/Cas9 targeting events cause complex deletions and insertions at 17 sites in the mouse genome, Nature Communications

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