Genome Editing in Livestock
Another Breeding Tool for Genetic Improvement?
As a beef cattle producer and the Chief Scientific of Acceligen, the livestock food subsidiary of Recombinetics, Tad Sonstegard is in a position to offer a moderate, informed opinion of this technology while standing at the water cooler.
Tad provides tangible examples of how gene editing has already shown it can benefit the livestock sector through the potential for “precise cross-breeding.”
One example discussed as an introduction to gene editing is the potential to select for polled dairy cattle, which removed the need for de-horning and improved animal welfare. These genetics have been selectively bred (the old-fashioned way) for generations via the polled beef breeds and, as such, have been part of the human food chain for thousands of years. One positive signal towards the potential acceptance of this technology is that the Humane Society of the United States has endorsed the use of gene editing technology to select for polled animals on the grounds that it reduces pain and suffering for livestock. More importantly, it also agreed to evaluate and endorse the application of gene editing on a case by case basis depending on its impact on animal welfare.
CRISPR is also being used to mitigate the greenhouse gas impacts of food production, with the most potential for use in the developing world through improving heat tolerance. Heat affects the disease resistance, nutrition, productivity and health of animals. Tad talks of how it takes nine dairy cows in India to produce the milk of one dairy cow in the US, with much of this difference due to lower productivity due to heat stress. If this technology eliminated this productivity gap, the GHG emissions and environmental impact of up to eight cows could be removed with no corresponding loss of milk production while also freeing up the food, water and other inputs currently directed to those eight animals. One application of selective breeding is showing great promise. It takes advantage of animals, referred to as “slick,” which have a hide comprised of hair that is less dense and half the normal length in addition to possessing larger, more active sweat glands. This combination allows “slick” animals to maintain a lower body temperature in more heat-stressful conditions.
In closing, Tad talks of future applications for gene editing and where the greatest economic benefits may lie, which appears to be in addressing disease resistance. More work does need to be done here as we don’t yet understand which areas of the genome are important when it comes to health. With a better basic understanding however, comes the ability to select for innate immunity as well as using rational design techniques that allow animals to better defend against bacteria and viruses. While the means discussed here differ, the ends are similar to those currently being pursued via more traditional methods in the Genome Canada Pig Resilience Project led by UAlberta’ Mike Dyck.
Watch the video summary for a more in-depth look at these and other editing applications