Expectations
New genetic engineering techniques (NGTs) are being used in animal breeding to develop livestock for more or better meat. This involves knocking out gene variants in various animal species of the so-called myostatin gene (MSTN), which is responsible for controlling muscle growth. The aim is to increase meat production. These effects are already known from conventional cattle breeding, where they are associated with higher meat yields, but also considerable animal welfare problems. New genetic engineering is, therefore, aiming to introduce this trait into animals and breeds where these gene variants have not previously been present.

Another approach to increasing meat production is centred on the leptin gene, which is responsible for the regulation of appetite. If this gene is blocked with NGTs, the animals eat more and can therefore gain weight more quickly. This should make animal husbandry more cost-effective, and meat and fish production more efficient.

Reality
Similar experiments have been carried out on cattle, sheep, pigs, fish and dogs.

Stillbirths, organ damage and malformations occurred in pigs during these experiments. Cloning is often used in NGT applications in pigs, sheep and cattle, and could therefore be relevant in this context, as these procedures are known to frequently lead to errors in gene regulation.

While most projects in mammals are still in the research and development phase, fish with increased muscle growth and accelerated weight gain are already being commercialised in Japan. As expected, animal welfare issues are an issue: sea bream with a defective MSTN gene not only have increased muscle growth, but also shortened body length and misalignment of the dorsal vertebrae. Compared to non-genetically engineered fish, they gain weight faster and appear to move less. Pufferfish with a blocked leptin gene suffer from a metabolic disorder or diabetes-like symptoms, which is the reason they gain weight faster and become heavier than their conspecifics. None of these NGT fish have been subjected to a thorough risk assessment by the authorities. Here, profit comes at the expense of animal health.

Consequences
New genetic engineering is being used in attempts to breed animals especially suitable for intensive livestock farming. The altered traits mean that these NGT animals may need less feed and can be slaughtered within shorter periods of time, thus enabling greater numbers of animals to be fattened and meat production to be increased. However, this also reinforces undesirable developments in factory farming, increases the overall burden on the environment and is associated with considerable animal welfare problems. Consumers have so far shown very little interest in buying such products. For example, demand for transgenic salmon, which supposedly grows faster and can be marketed, amongst others, in Canada, was so low that the economic survival of the company behind it, AquaBounty, is at stake .

Further information:
TA report
Expert opinion on new genetic engineering