“Super-muscly pigs”

An aspiration for industrial food production, a nightmare for the pigs

New Genetic Engineering techniques, such as CRISPR/Cas gene scissors, are being used to produce, amongst others, farm animals with increased muscle growth. However, the use of the gene scissors is frequently problematic in cattle and pigs: individual cells are often removed from the skin of the animals, then genetically engineered with CRISPR/Cas and afterwards converted into embryonic cells using cloning processes, such as those used for Dolly the sheep. As a result, there are not only problems with the altered genes, but also with gene regulation, which is seriously disrupted by the cloning process. Many animals are born sick and die shortly after birth.

One particular project being pursued is the use of New Genetic Engineering techniques (New GE) to produce so-called ‘double muscle animals’. In various experiments with pigs, cows, sheep and goats, attempts have been made to switch off the myostatin gene (MSTN) which controls muscle growth. As a result, the muscle cells multiply at an unnatural rate. However, this can cause considerable animal health problems: experiments in China show that only eight piglets out of 900 genetically engineered embryos survived with the desired genetic engineered changes. Many also died in the first few months. The piglets suffered from health problems such as thickened tongues. After many more attempts, seemingly healthy specimens were born. However, making statements about their actual health is difficult because they were slaughtered early for further investigation.

This example shows: New GE in farm animals is by no means free of side effects and is often associated with animal suffering.  Applications of New Genetic Engineering techniques can result in plants and animals with extreme biological characteristics, which go beyond what can be achieved in conventional breeding. Without mandatory approval processes and a prospective technology assessment, more and more genetically engineered plants and animals may enter the market without having undergone detailed risk assessment – and also have ethically questionable traits. It would pave the way for ‘progress’ to go in the wrong direction – with serious consequences for humans, animals and the environment.

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Further information: 
Source: Wang et al. (2015) Efficient Generation of Myostatin Mutations in Pigs Using the CRISPR/Cas9 System

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