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Abstract：
Inbreeding depression is a growing concern in livestock because it can detrimentally affect animal fitness, health, and production levels. Genomic information can be used to more effectively capture variance in Mendelian sampling, thereby enabling more accurate estimation of inbreeding, but further progress is still required. The calculation of inbreeding for herd management purposes is largely still done using pedigree information only, although inbreeding coefficients calculated in this manner have been shown to be less accurate than genomic inbreeding measures. Continuous stretches of homozygous genotypes, so called runs of homozygosity, have been shown to provide a better estimate of autozygosity at the genomic level than conventional measures based on inbreeding coefficients calculated through conventional pedigree information or even genomic relationship matrices. For improved and targeted management of genomic inbreeding at the population level, the development of methods that incorporate genomic information in mate selection programs may provide a more precise tool for reducing the detrimental effects of inbreeding in dairy herds. Additionally, a better understanding of the genomic architecture of inbreeding and incorporating that knowledge into breeding programs could significantly refine current practices. Opportunities to maintain high levels of genetic progress in traits of interest while managing homozygosity and sustaining acceptable levels of heterozygosity in highly selected dairy populations exist and should be examined more closely for continued sustainability of both the dairy cattle population as well as the dairy industry. The inclusion of precise genomic measures of inbreeding, such as runs of homozygosity, inbreeding, and mating programs, may provide a path forward. In this symposium review article, we describe traditional measures of inbreeding and the recent developments made toward more precise measures of homozygosity using genomic information. The effects of homozygosity resulting from inbreeding on phenotypes, the identification and mapping of detrimental homozygosity haplotypes, management of inbreeding with genomic data, and areas in need of further research are discussed.
摘要：
近亲繁殖抑郁症在牲畜中日益受到关注，因为它会对动物健康产生不利影响，健康,和生产水平。基因组信息可用于更有效地捕获孟德尔采样中的方差，从而能够更准确地估计近亲繁殖，但仍需取得进一步进展。为羊群管理目的的近亲繁殖的计算在很大程度上仍然仅使用谱系信息，尽管以这种方式计算的近交系数已被证明不如基因组近交测量准确。纯合基因型的连续延伸，所谓的纯合性运行，已被证明在基因组水平上提供了比基于通过常规谱系信息甚至基因组关系矩阵计算的近交系数的常规措施更好的自合性估计。为了在种群水平上改善和有针对性地管理基因组近交，在配偶选择程序中整合基因组信息的方法的发展可能为减少奶牛群近亲繁殖的有害影响提供更精确的工具。此外,更好地了解近亲繁殖的基因组结构并将这些知识纳入育种计划可以显着改善当前的实践。在高度选择的乳品群体中，存在保持感兴趣的性状的高水平遗传进展，同时管理纯合性并维持可接受的杂合性水平的机会，应该更仔细地检查奶牛群体和乳品行业的持续可持续性。包括近亲繁殖的精确基因组测量，例如纯合性的运行，近亲繁殖,和交配程序，可以提供前进的道路。在这篇研讨会综述文章中，我们描述了近亲繁殖的传统方法，以及使用基因组信息更精确地测量纯合性的最新进展。近交纯合性对表型的影响，有害纯合性单倍型的鉴定和作图，用基因组数据管理近亲繁殖，并讨论了需要进一步研究的领域。
