Department of Animal Sciences, University of Florida, Gainesville 32611.
Department of Animal Sciences, University of Florida, Gainesville 32611; Faculdade de Medicina Veterinária, Universidade Federal de Uberlândia, Uberlândia MG 38400-902, Brazil.
J Dairy Sci. 2020 Apr;103(4):3304-3311. doi: 10.3168/jds.2019-17767. Epub 2020 Feb 13.
Service sire has been recognized as an important factor affecting dairy herd fertility. Our group has reported promising results on gene mapping and genomic prediction of dairy bull fertility using autosomal SNP markers. Little is known, however, about the genetic contribution of sex chromosomes, which are enriched in genes related to sexual development and reproduction. As such, the main goal of this study was to investigate the effect of SNP markers on X and Y chromosomes (BTAX and BTAY, respectively) on sire conception rate (SCR) in US Holstein bulls. The analysis included a total of 5,014 bulls with SCR records and genotypes for roughly 291k SNP located on the autosomes, 1.5k SNP located on the pseudoautosomal region (PAR), 13.7k BTAX-specific SNP, and 24 BTAY-specific SNP. We first performed genomic scans of the sex chromosomes, and then we evaluated the genomic prediction of SCR including BTAX SNP markers in the predictive models. Two markers located on PAR and 3 markers located on the X-specific region showed significant associations with sire fertility. Interestingly, these regions harbor genes, such as FAM9B, TBL1X, and PIH1D3, that are directly implicated in testosterone concentration, spermatogenesis, and sperm motility. On the other hand, BTAY showed very low genetic variability, and none of the segregating markers were associated with SCR. Notably, model predictive ability was largely improved by including BTAX markers. Indeed, the combination of autosomal with BTAX SNP delivered predictive correlations around 0.343, representing an increase in accuracy of about 7.5% compared with the standard whole autosomal genome approach. Overall, this study provides evidence of the importance of both PAR and X-specific regions in male fertility in dairy cattle. These findings may help to improve conception rates in dairy herds through accurate genome-guided decisions on bull fertility.
服务 sire 已被认为是影响奶牛群繁殖力的一个重要因素。我们的团队已经报告了使用常染色体 SNP 标记对奶牛公牛繁殖力进行基因图谱和基因组预测的有希望的结果。然而，关于性染色体的遗传贡献知之甚少，性染色体富含与性发育和生殖有关的基因。因此，本研究的主要目标是研究 SNP 标记对 X 和 Y 染色体（分别为 BTAX 和 BTAY）对美国荷斯坦公牛 sire 受孕率（SCR）的影响。该分析共包括 5014 头 sire 受孕率记录和基因型的公牛，这些基因型大约包括 291k 个位于常染色体上的 SNP、1.5k 个位于假常染色体区（PAR）上的 SNP、13.7k 个 BTAX 特异性 SNP 和 24 个 BTAY 特异性 SNP。我们首先对性染色体进行基因组扫描，然后评估包括 BTAX SNP 标记在内的 sire 受孕率的基因组预测在预测模型中的作用。位于 PAR 上的 2 个标记和位于 X 特异性区域的 3 个标记与 sire 繁殖力显著相关。有趣的是，这些区域包含直接影响睾酮浓度、精子发生和精子活力的基因，如 FAM9B、TBL1X 和 PIH1D3。另一方面，BTAY 显示出非常低的遗传变异性，没有分离标记与 SCR 相关。值得注意的是，通过包含 BTAX 标记，模型的预测能力得到了很大的提高。事实上，常染色体与 BTAX SNP 的组合提供了约 0.343 的预测相关性，与标准全常染色体基因组方法相比，准确性提高了约 7.5%。总的来说，这项研究提供了 PAR 和 X 特异性区域在奶牛雄性繁殖力中的重要性的证据。这些发现可能有助于通过对公牛繁殖力进行准确的基因组指导决策来提高奶牛群的受孕率。
