BACKGROUND Crossbreeding is widely used in pig production because of the benefits of heterosis effects and breed complementarity. Commonly, sire lines are bred for traits such as feed efficiency, growth and meat content, whereas maternal lines are also bred for reproduction and longevity traits, and the resulting three-way crossbred pigs are used for production of meat. The most important genetic basis for heterosis is dominance effects, e.g. removal of inbreeding depression. The aims of this study were to (1) present a modification of a previously developed model with additive, dominance and inbreeding depression genetic effects for analysis of data from a purebred sire line and three-way crossbred pigs; (2) based on this model, present equations for additive genetic variances, additive genetic covariance, and estimated breeding values (EBV) with associated accuracies for purebred and crossbred performances; (3) use the model to analyse four production traits, i.e. ultra-sound recorded backfat thickness (BF), conformation score (CONF), average daily gain (ADG), and feed conversion ratio (FCR), recorded on Danbred Duroc and Danbred Duroc-Landrace-Yorkshire crossbred pigs reared in the same environment; and (4) obtain estimates of genetic parameters, additive genetic correlations between purebred and crossbred performances, and EBV with associated accuracies for purebred and crossbred performances for this data set. RESULTS Additive genetic correlations (with associated standard errors) between purebred and crossbred performances were equal to 0.96 (0.07), 0.83 (0.16), 0.75 (0.17), and 0.87 (0.18) for BF, CONF, ADG, and FCR, respectively. For BF, ADG, and FCR, the additive genetic variance was smaller for purebred performance than for crossbred performance, but for CONF the reverse was observed. EBV on Duroc boars were more accurate for purebred performance than for crossbred performance for BF, CONF and FCR, but not for ADG. CONCLUSIONS Methodological developments led to equations for genetic (co)variances and EBV with associated accuracies for purebred and crossbred performances in a three-way crossbreeding system. As illustrated by the data analysis, these equations may be useful for implementation of genomic selection in this system.

中文翻译：

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具有加性，显性和近亲抑制作用的双变量基因组模型，用于父系和三向杂交猪。

背景技术由于杂种优势和品种互补性的优点，杂交育种被广泛用于猪的生产中。通常，公母系的繁殖具有饲料效率，生长和肉含量等特性，而母系也具有繁殖和长寿性状，因此，将三元杂交猪用于生产肉。杂种优势最重要的遗传基础是优势效应，例如消除近交抑郁症。这项研究的目的是（1）提出对先前开发的具有加性，显性和近亲抑郁遗传效应的模型的修改，以分析来自纯种公系和三向杂交猪的数据；（2）基于该模型，给出了加性遗传方差，加性遗传协方差的等式，以及纯种和杂种性能的估计育种值（EBV）及相关的准确性；（3）使用该模型分析在Danbred Duroc和Danbred上记录的四个生产特性，即超记录的背脂肪厚度（BF），构象得分（CONF），平均日增重（ADG）和饲料转化率（FCR）。在相同环境中饲养的杜洛克-兰德雷斯-约克郡杂交猪；（4）获得该数据集的遗传参数，纯种和杂种表现之间的加性遗传相关性估计，以及EBV及其相关纯种和杂种表现的准确性。结果BF，CONF，ADG和FCR的纯种和杂种性能之间的加性遗传相关性（相关标准误差）分别等于0.96（0.07），0.83（0.16），0.75（0.17）和0.87（0.18）。对于高炉 ADG和FCR，纯种性能的加成遗传方差小于杂种性能，但对于CONF则相反。对于BF，CONF和FCR，杜洛克公猪的EBV较纯种性能更准确，而对ADG而言，EBV较纯种性能更准确。结论方法学的发展导致了遗传（共）方差和EBV的方程式，以及在三元杂交系统中纯种和杂种表现的相关精度。如数据分析所示，这些等式对于在该系统中实施基因组选择可能是有用的。CONF和FCR，但不适用于ADG。结论方法学的发展导致了遗传（共）方差和EBV的方程式，以及在三元杂交系统中纯种和杂种表现的相关精度。如数据分析所示，这些等式对于在该系统中实施基因组选择可能是有用的。CONF和FCR，但不适用于ADG。结论方法学的发展导致了遗传（共）方差和EBV的方程式，以及在三元杂交系统中纯种和杂种表现的相关精度。如数据分析所示，这些等式对于在该系统中实施基因组选择可能是有用的。