Average daily gain (ADG) in pigs is affected by both direct and social genetic effects (SGE). However, selection for SGE in purebreds has not conclusively been shown to improve ADG in crossbreds, and it is unknown whether SGE in purebreds are equal to those in crossbreds. Moreover, SGE may reflect dominance related behaviour, which is affected by the variation in body weight within a group. Therefore, we hypothesized that (a) there is a positive effect of parent average SGE estimated in purebred pigs on phenotypic ADG in crossbred offspring, and (b) there is an interaction between SGE on ADG and standard deviation in starting weight of pigs within the group. We also hypothesized that (c) social genetic variance for ADG exists in crossbred pigs, and (d) there is a favourable genetic correlation between SGE on ADG in purebred and crossbred pigs. We found a statistically significant interaction between the standard deviation in starting weight and SGE within groups, and conditioning on the mean standard deviation in starting weight, we found a favourable regression coefficient (0.37 ± 0.21) of ADG in crossbreds on SGE in purebreds. Variances for SGE were small in both Landrace (L) and Yorkshire (Y), and higher for SGE in both the dam and sire component of crossbred YL. The genetic correlations between SGE in purebreds and the dam or sire component of SGE in crossbreds were also favourable (0.52 ± 0.48 and 0.34 ± 0.42, respectively), although not significantly different from 0. We confirmed that there is a positive effect of SGE estimated using purebred information on phenotypic ADG in crossbreds, and that the largest effect is achieved when the within-group variation in starting weight is small. Our results indicate that social genetic variance in crossbreds exists and that there is a favourable genetic correlation between social genetic effects in purebreds and crossbreds. Collectively, our results indicate that selection for SGE on ADG in purebreds in a nucleus farm environment with little competition for resources can improve ADG in crossbreds in a commercial environment.

中文翻译：

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选择纯种的社会遗传效应可提高杂种的生长

猪的平均日增重（ADG）受直接和社会遗传效应（SGE）的影响。然而，尚无定论表明在纯种中选择SGE可以改善杂种中的ADG，并且尚不清楚纯种中的SGE是否与杂种中的SGE相等。此外，SGE可能反映了与优势有关的行为，而行为受到组内体重变化的影响。因此，我们假设（a）纯种猪的母本平均SGE对杂交后代的表型ADG有积极影响，并且（b）SGE对ADG的影响与标准差内标准猪的初始体重之间存在相互作用。团体。我们还假设（c）杂种猪存在ADG的社会遗传变异，并且（d）纯种和杂种猪中ADG的SGE之间存在良好的遗传相关性。我们发现各组中起始体重的标准偏差和SGE之间的统计显着性相互作用，并以起始体重的平均标准偏差为条件，我们发现纯种SGE上杂种中ADG的有利回归系数（0.37±0.21）。在Landrace（L）和Yorkshire（Y）中，SGE的变异都较小，而在杂交YL的母犬和父系中，SGE的变异都较高。尽管纯种SGE与杂种中SGE的母乳或父系成分之间的遗传相关性也很好（分别为0.52±0.48和0.34±0.42），但与0差异不显着。我们证实，SGE估计有积极作用使用有关杂交表型ADG的纯种信息，当组内起始重量变化较小时，可获得最大的效果。我们的结果表明，杂种中存在社会遗传变异，并且纯种和杂种中的社会遗传效应之间存在良好的遗传相关性。总体而言，我们的结果表明，在有核资源的农场中，在纯种中选择ADG上的SGE，对资源的竞争很少，可以在商业环境中提高杂交中的ADG。