The US FDA (Food and Drug Administration) has approved cattle for use in agriculture that are genetically engineered with CRISPR/Cas to have reduced hair growth. 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, both of which have also filed 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 produce cattle with reduced hair growth. This is a breeding trait called SLICK, which is already known in traditional breeding. Animals with this trait are, according to various studies, better able to cope with higher ambient temperatures.
This is the second attempt in the US to market CRISPR/Cas cattle. In 2019, the FDA rejected the approval of hornless cattle engineered with New GE (New Genetic Engineering) after serious flaws became apparent, which were also passed on to the next generation [LINK]. All the genetically engineered cattle had to be slaughtered.
Unintended genetic changes have also been found in the approved Recombinetics cattle, although the US FDA considered these 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 produce 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 also warn that breeding material from the animals, such as sperm, could be imported into the EU. If breeding material from the genetically engineered animals is imported without effective controls, this genetic material and any possible hereditary defects could spread rapidly in 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 appears possible and marketable will be tried out. In this case, genetic engineering was used to ‘produce’ and patent a breeding trait already known in conventional breeding. From the perspective of a technology impact assessment, the genetically engineered animals do not have any significant advantages compared to conventionally-bred animals. On the other hand, the uncertainties associated with the unintended genetic changes, the additional animal experiments and the effects of patenting are likely to deter many animal owners and breeders.