Short-hair CRISPR cattle

CRISPR to equip cattle for climate change

The US FDA (Food and Drug Administration) has decided in favour of allowing CRIPSR/Cas cattle with short, slick coats for agricultural purposes. The shorter hair is said to let the cattle more easily withstand hot weather, and thus gain weight faster. However, the supposed advantages of the gene scissors application are questionable – and the desired characteristics can also be achieved using conventional breeding.

The animals will be marketed by Recombinetics and its affiliated company Acceligen, which have also filed for patents on the cattle. The companies developed the cattle by using CRISPR/Cas to alter the genes of a receptor for the hormone prolactin. The aim was to generate cattle with shorter hair, a trait called SLICK which is already known from traditional breeding. Animals with this breeding trait are, according to various studies, better able to cope with higher ambient temperatures.

This is the second time that the US has attempted to market cattle genetically engineered with CRISPR/Cas. In 2019, the FDA rejected the approval of hornless cattle engineered with New GE (New Genetic Engineering). However, serious errors became apparent, which were also passed on to the next generation[LINK]. All the genetically engineered cattle had to be slaughtered. Nevertheless, experts who are now calling the SLICK GE cattle a success were also involved in these previous experiments.

Other unintended genetic changes were found in the approved the Recombinetics cattle, these were, however, considered to be less severe. At the same time, the data provided by the FDA includes no indication of whether the animals will stay healthy over their lifetime. The reason: only four calves were examined, one of which was not genetically engineered, probably because the gene scissors had failed to work as expected. Another calf died unexpectedly, but the FDA assumes that this incident was not related to the genetic intervention.

To produce the cattle, the gene scissors were injected into embryos, which were then transferred to surrogate mother cows. This process is known to be associated with failures and also diseased animals. It is remarkable that neither of the ‘successfully’ genetically engineered animals show the intended changes consistently in all the cells of their body. This phenomenon is known as genetic mosaicism or chimeric formation.

Experts warn that breeding material from the animals, such as sperm, could also be imported into the EU. If imports are carried out without effective controls, the genetic material of the genetically engineered animals and thus possible hereditary defects could spread rapidly in cattle herds.

This example raises the question of how we should deal with genetically engineered organisms in principle. The technical possibilities mean that (almost?) everything that seems possible and marketable will also be done and tried out. In this case, a breeding trait, which is already known from conventional breeding, is 'produced' by means of genetic engineering and patented. From the perspective of technology impact assessment, the genetically engineered animals do not show any significant advantages compared to those from conventional breeding. On the other hand, the uncertainties associated with the unintended genetic changes, the additional animal experiments carried out and the effects of patenting are likely to have a deterrent effect on many animal owners.



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