Canadienne cattle are the oldest breed of dairy cattle in North America. The Canadienne breed originates from cattle that were brought to America by the mid-seventeenth century French settlers. The herd book was established in 1886 and the current breed characteristics include dark coat color, small size compared to the modern Holstein breed, and overall rusticity shaped by the harsh environmental conditions that were prevalent during the settlement of North America. The Canadienne breed is an invaluable genetic resource due to its high resilience, longevity and fertility. However, it is heavily threatened with a current herd limited to an estimated 1200 registered animals, of which less than 300 are fullblood. To date, no effort has been made to document the genetic pool of this heritage breed in order to preserve it. In this project, we used genomic data, which allow a precise description of the genetic makeup of a population, to provide valuable information on the genetic diversity of this heritage breed and suggest management options for its long-term viability. Using a panel that includes 640,000 single nucleotide polymorphisms (SNPs), we genotyped 190 animals grouped into six purity ranges. Unsupervised clustering analyses revealed three genetically distinct groups among those with the higher levels of purity. The observed heterozygosity was higher than expected even in the 100% purebreds. Comparison with Holstein genotypes showed significantly shorter runs of homozygosity for the Canadienne breed, which was unexpected due to the high inbreeding value calculated from pedigree data. Overall, our data indicate that the fullblood gene pool of the Canadienne breed is more diversified than expected and that bloodline management could promote breed sustainability. In its current state, the Canadienne is not a dead-end breed but remains highly vulnerable due to its small population size.

中文翻译：

---

Canadienne 奶牛品种遗传库的特征

Canadienne 牛是北美最古老的奶牛品种。Canadienne 品种起源于 17 世纪中叶法国定居者带到美国的牛。畜群登记簿成立于 1886 年，目前的品种特征包括深色毛色、与现代荷斯坦品种相比体型较小，以及北美定居期间普遍存在的恶劣环境条件塑造的整体质朴。Canadienne 品种是一种宝贵的遗传资源，因为它具有高韧性、长寿和生育能力。然而，它受到严重威胁，因为目前的畜群估计只有 1200 只注册动物，其中不到 300 只是纯血统。迄今为止，还没有人努力记录这个传统品种的基因库以保护它。在这个项目中，我们使用基因组数据来准确描述种群的遗传构成，以提供有关该传统品种遗传多样性的宝贵信息，并为其长期生存能力提出管理方案。使用包含 640,000 个单核苷酸多态性 (SNP) 的面板，我们对 190 只动物进行了基因分型，分为六个纯度范围。无监督聚类分析揭示了三个具有较高纯度水平的基因组。即使在 100% 纯种中，观察到的杂合性也高于预期。与 Holstein 基因型的比较显示，Canadienne 品种的纯合子运行明显较短，这是出乎意料的，因为根据系谱数据计算出的近亲繁殖值很高。全面的，我们的数据表明，Canadienne 品种的全血基因库比预期更加多样化，血统管理可以促进品种的可持续性。在目前的状态下，Canadienne 并不是一个死胡同，但由于其人口规模小，仍然非常脆弱。