Pacheco Hendyel A, Rossoni Attilio, Cecchinato Alessio, Peñagaricano Francisco
Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI, United States.
Italian Brown Breeders Association, Verona, Italy.
Front Genet. 2023 Jul 6;14:1227310. doi: 10.3389/fgene.2023.1227310. eCollection 2023.
Intensive selection for improved productivity has been accompanied by an increase in inbreeding rates and a reduction in genetic diversity. The increase in inbreeding tends to impact performance, especially fitness-related traits such as male fertility. Inbreeding can be monitored using runs of homozygosity (ROH), defined as contiguous lengths of homozygous genotypes observed in an individual's chromosome. The goal of this study was to evaluate the presence of ROH in Italian Brown Swiss cattle and assess its association with bull fertility. First, we evaluated the association between ROH and male fertility using 1,102 Italian Brown Swiss bulls with sire conception rate records and 572 K SNPs spanning the entire genome. Second, we split the entire population into 100 high-fertility and 100 low-fertility bulls to investigate the potential enrichment of ROH segments in the low-fertility group. Finally, we mapped the significant ROH regions to the bovine genome to identify candidate genes associated with sperm biology and male fertility. Notably, there was a negative association between bull fertility and the amount of homozygosity. Four different ROH regions located in chromosomes 6, 10, 11, and 24 were significantly overrepresented in low-fertility bulls (Fisher's exact test, -value <0.01). Remarkably, these four genomic regions harbor many genes such as , , , , , , , , and that are related to sperm biology and male fertility. Overall, our findings suggest that inbreeding and increased homozygosity have a negative impact on male fertility in Italian Brown Swiss cattle. The quantification of ROH can contribute to minimizing the inbreeding rate and avoid its negative effect on fitness-related traits, such as male fertility.
为提高生产力而进行的高强度选择伴随着近亲繁殖率的增加和遗传多样性的减少。近亲繁殖的增加往往会影响性能，尤其是与健康相关的性状，如雄性生育力。可以使用纯合子片段（ROH）来监测近亲繁殖，ROH定义为在个体染色体中观察到的纯合基因型的连续长度。本研究的目的是评估意大利褐牛中ROH的存在情况，并评估其与公牛生育力的关联。首先，我们使用1102头有父系受胎率记录的意大利褐牛公牛和覆盖整个基因组的572K个单核苷酸多态性（SNP），评估了ROH与雄性生育力之间的关联。其次，我们将整个群体分为100头高生育力公牛和100头低生育力公牛，以研究低生育力组中ROH片段的潜在富集情况。最后，我们将显著的ROH区域定位到牛基因组上，以识别与精子生物学和雄性生育力相关的候选基因。值得注意的是，公牛生育力与纯合度之间存在负相关。位于6号、10号、11号和24号染色体上的四个不同的ROH区域在低生育力公牛中显著富集（Fisher精确检验，P值<0.01）。值得注意的是，这四个基因组区域包含许多与精子生物学和雄性生育力相关的基因，如[此处原文缺失具体基因名称]。总体而言，我们的研究结果表明，近亲繁殖和纯合度增加对意大利褐牛的雄性生育力有负面影响。ROH的量化有助于将近亲繁殖率降至最低，并避免其对与健康相关性状（如雄性生育力）的负面影响。
