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

加拿大已成为世界领先的家畜遗传学，特别是在奶牛和猪。然而，全球食品市场的持续变化要求除了生产性状之外，其他性状，如营养成分，产品质量，动物健康和福利是牲畜选择计划的优先目标。基因组编辑技术被认为是帮助开发更可持续的动物生产系统的强大工具，因为它能够快速调节所需动物谱系的性状，这是通过传统育种方法难以或不可能实现的。使用基于CRISPR-Cas9系统的基因组编辑技术，现在可以非常精确地操纵控制高价值性状的DNA序列，其结果与自然界中随机发生的突变相同。在养猪生产中，仔猪阉割是必要的，以避免公猪的污点，即，来自非阉割猪的肉散发出令人不快的气味和味道，但它代表了动物福利的重要问题，并具有重要的伦理、管理和经济意义。因此，迫切需要开发工具和策略，以满足消费者的要求和有关仔猪去势的新法规。本研究计划旨在开发一种替代仔猪去势的方法来预防公猪异味。这将通过选择性地减少雄烯酮的产生（公猪异味的关键因素）来实现，通过取代雄烯酮合成酶CYP 17 A1和CYB 5中的两个氨基酸。根据以前的研究，预计这将减少公猪的臭味，同时保持其他性类固醇的正常生产，负责提高饲料效率和瘦肉产量的完整的公猪。这将对加拿大的养猪业和经济产生巨大影响。

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.