Genetically engineered “super-muscly pigs” for the meat industry

What is it about?

New methods of genetic engineering, such as the gene scissors CRISPR/Cas, are being used to produce animals with enhanced muscle growth. These are so-called “super-muscly pigs”. Various experiments have been carried out with pigs, cattle, sheep and goats to “knock-out” the myostatin (MSTN) gene which controls muscle growth. If MSTN is disrupted, there is an abnormal proliferation of muscle cells. These experiments have been successful in some animals; and in some cases patents have been filed on the resulting pigs and cattle.

Why is this problematic?

  • Economic interests are clearly at the forefront of these experiments whilst animal welfare is being completely neglected.
  • There have been serious problems with piglets: The first experiments in China were carried out with 900 embryos, but only 8 piglets showed the desired traits. All of them died within the first few months of life. The piglets had health problems such as thickened tongues.
  • Further numerous experiments appeared to produce healthier animals. However, it is difficult to establish whether these animals are really healthy because they were slaughtered early on for use in other experiments.
  • It seems that even the scientists are concerned about the consequences of their work: A Korean team of scientists is planning to sell the sperm of the genetically engineered pigs for use in breeding with “normal” pigs in the hope that the resulting animals will be healthier and not quite so muscly.
  • Cloning methods are often used in the research and development of “double-muscled animals”. These can also lead to many unwanted side effects, such as adverse effects on health and stillbirths.
  • Currently, it is unclear under which conditions the animals would need to be kept. Would they need more feed and more protein in their feed for additional muscle mass? This would pose new challenges in agriculture. In all probability, more antibiotics would be needed due to the animals being more susceptible to stress and disease.

Various stakeholders are demanding that more genetically engineered plants and animals are approved for marketing without any requirements for risk assessment or labelling if no additional genes have been inserted. In the case at issue, offspring of pigs from China and South Korea could enter the EU market unnoticed.

Further information
African swine fever now occurs more frequently in Europe and, therefore, genetic researchers have been concentrating on producing pigs that are resistant to this disease. In experiments they have used genetic editing techniques to transfer a gene from wart hogs that confers resistance to swine fever to fattening pigs. If these pigs come onto the EU market for fattening, there could be serious consequences for pig farming as a whole: Whilst the genetically engineered pigs might not be taken ill with the swine fever virus, they might, nevertheless, carry the virus. As a result, the fever could spread and affect non-genetically engineered production because these pigs would not be resistant. This could mean that pig farmers would have no option but to use genetically engineered animals – possibly leading to unmodified pig farming being completely banned. Ultimately, this could conceivably be a huge business opportunity for the developers of patented pigs.

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