Birth weight (BW) in animal production is an economically important trait in prolific species. The laboratory mouse (Mus musculus) is used as an experimental animal because it is considered a suitable model for prolific species such as rabbits and pigs. Two mouse lines were divergently selected for birth weight variability with a third line of non-selected control population of the same origin as the animals starting the experiment. The objective of this study was, therefore, to compare and evaluate the differential response of each line. The animals were from the 17th generation of both low and high BW variability lines of the divergent selection experiment, including in addition animals from the control line. The dataset contained 389 records from 48 litters of the high line, 734 records from 73 litters of the low line, and 574 records from 71 litters of the control line. The studied traits were as follows: the BW, the BW variance, the BW standard deviation, the BW coefficient of variation within-litter, the weaning weight (WW), the litter size at birth and at weaning, the weight gain, and the preweaning survival. The model included the line effect jointly with the parturition number and its interaction, the linear and quadratic LS as covariates except for the LS trait itself when analyzing litter traits, as well as the pup sex when analyzing individual traits. The low line had a lower BW and WW, but a higher litter size, and greater robustness owing to a higher survival at weaning. As a model of livestock animals, the findings from this experiment led to a proposal of selection for pig production that would combine an increase in litter size with higher survival and welfare. Compared with the control line, a much higher response was observed in the low variability line than in the high line, making it extremely satisfactory given that homogeneity provides advantages in terms of animal welfare and robustness.

中文翻译：

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与对照品系相比，小鼠的出生体重变异性的不同选择实验中的选择响应。

动物生产中的出生体重（BW）是多产物种的一项重要经济特征。实验老鼠（Mus musculus ）用作实验动物，因为它被认为是多产物种（例如兔和猪）的合适模型。为了出生体重的差异，分别选择了两只小鼠品系，第三只未选择的对照种群与开始实验的动物具有相同的起源。因此，本研究的目的是比较和评估每条线的差异响应。这些动物来自发散选择实验的第17代低和高BW变异系，另外还包括来自对照系的动物。数据集包含来自高线的48窝的389条记录，来自低线的73窝的734条记录和来自控制线的71窝的574条记录。研究的特征如下：体重，体重方差，体重标准差，仔猪内的体重变化系数，断奶体重（WW），出生和断奶时的产仔数，体重增加和断奶前的存活率。该模型包括线效应，分娩数及其相互作用，线性和二次线性LS作为协变量，除了分析同窝性状时的LS性状本身以及分析单个性状时的幼崽性。低位线具有较低的体重和WW，但具有较高的窝产仔数，并且由于断奶时的存活率较高，因此具有更高的坚固性。作为家畜动物的模型，该实验的发现导致提出了选择生猪的建议，该建议将增加产仔数与更高的生存和福利相结合。与控制线相比，在低变异性线中观察到的响应要比在高变异性线中高得多，