Improvement of swine lineages for increased productivity, product quality, animal health and welfare

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Canada has become a world leader in livestock genetics, especially in dairy cattle and swine. However, ongoing changes in the global food market require that other traits, in addition to production traits, such as nutrient composition, product quality, animal health and welfare to be priority objectives in livestock selection programs. Genome-editing technology is envisioned as powerful tool to help developing more sustainable animal production systems since it enables a quick modulation of traits in a desired lineage of animals, which would be difficult or impossible to achieve via traditional breeding approaches. Using genome editing technologies based on the CRISPR-Cas9 system it is now possible to manipulate DNA sequences that control high value traits very precisely in a way that the result will be identical to mutations that occur randomly in nature. In swine production, piglet castration is necessary to avoid boar taint, i.e., the unpleasant odor and flavor emanating from meat originating from non-castrated pigs, but it represents an important issue for animal welfare and has important ethical, management and economic implications. Therefore, there is an urgent need to develop tools and strategies to address requirements from consumers and new regulations regarding piglet castration. This research proposal has been prepared to develop an alternative to piglet castration for preventing boar taint. This will be achieved by selectively decreasing the production of androstenone (a key factor for boar taint), by substituting two amino acids in the androstenone synthesis enzymes CYP17A1 and CYB5. Based on previous studies, this is anticipated to reduce boar taint while maintaining the normal production of other sex steroids responsible for the improved feed efficiency and lean yield of intact male pigs. This would have an enormous impact on the Canadian swine industry and economy.