Preselection of candidates, hereafter referred to as preselection, is a common practice in breeding programs. Preselection can cause bias and accuracy loss in subsequent pedigree-based best linear unbiased prediction (PBLUP). However, the impact of preselection on subsequent single-step genomic BLUP (ssGBLUP) is not completely clear yet. Therefore, in this study, we investigated, across different heritabilities, the impact of intensity and type of preselection on subsequent ssGBLUP evaluation of preselected animals. We simulated a nucleus of a breeding programme, in which a recent population of 15 generations was produced with PBLUP-based selection. In generation 15 of this recent population, the parents of the next generation were preselected using several preselection scenarios. These scenarios were combinations of three intensities of preselection (no, high or very high preselection) and three types of preselection (genomic, parental average or random), across three heritabilities (0.5, 0.3 or 0.1). Following each preselection scenario, a subsequent evaluation was performed using ssGBLUP by excluding all the information from the preculled animals, and these genetic evaluations were compared in terms of accuracy and bias for the preselected animals, and in terms of realized genetic gain. Type of preselection affected selection accuracy at both preselection and subsequent evaluation stages. While preselection accuracy decreased, accuracy in the subsequent ssGBLUP evaluation increased, from genomic to parent average to random preselection scenarios. Bias was always negligible. Genetic gain decreased from genomic to parent average to random preselection scenarios. Genetic gain also decreased with increasing intensity of preselection, but only by a maximum of 0.1 additive genetic standard deviation from no to very high genomic preselection scenarios. Using ssGBLUP in subsequent evaluations prevents preselection bias, irrespective of intensity and type of preselection, and heritability. With GPS, in addition to reducing the phenotyping effort considerably, the use of ssGBLUP in subsequent evaluations realizes only a slightly lower genetic gain than that realized without preselection. This is especially the case for traits that are expensive to measure (e.g. feed intake of individual broiler chickens), and traits for which phenotypes can only be measured at advanced stages of life (e.g. litter size in pigs).

中文翻译：

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研究预选对预选动物随后的单步基因组BLUP评估的影响。

候选者的预选（以下称为预选）是育种计划中的常见做法。预选会在随后的基于谱系的最佳线性无偏预测（PBLUP）中引起偏倚和准确性损失。但是，预选对后续单步基因组BLUP（ssGBLUP）的影响尚不完全清楚。因此，在这项研究中，我们跨不同的遗传力调查了预选强度和预选类型对随后的ssGBLUP评估预选动物的影响。我们模拟了一个育种程序的核心，其中使用基于PBLUP的选择产生了最近的15代种群。在这个最近人口的第15代中，使用几种预选方案对下一代的父母进行了预选。这些方案是三种遗传力（0.5、0.3或0.1）的三种预选强度（无，高或很高的预选）和三种预选类型（基因组，父母平均或随机）的组合。在每个预选方案之后，通过使用ssGBLUP排除已淘汰动物的所有信息来进行后续评估，并比较了这些遗传评估在预选动物的准确性和偏倚方面以及在已实现的遗传增益方面。预选的类型会影响预选和后续评估阶段的选择准确性。尽管预选准确性降低，但随后的ssGBLUP评估的准确性有所提高，从基因组平均数到亲本平均数再到随机预选场景。偏差总是微不足道的。遗传增益从基因组平均到亲本平均再到随机的预选场景都减少了。遗传增益也随着预选强度的增加而降低，但是从无到非常高的基因组预选方案最多只能增加0.1个附加遗传标准偏差。在后续评估中使用ssGBLUP可以防止预选偏倚，无论预选的强度和类型以及可遗传性如何。利用GPS，除了显着减少表型工作外，在后续评估中使用ssGBLUP只能实现比未进行预选时略低的遗传增益。对于昂贵的性状（例如个别肉鸡的采食量）和只能在生命的晚期阶段才能测定其表型的性状（例如猪的产仔数），尤其如此。