Postnatal piglet survival is important both in economic and animal welfare terms. It is influenced by the piglet’s own direct genetic effects and by maternal genetic effects of the dam, associated with milk production and mothering abilities. These genetic effects might be correlated, affected by other non-genetic factors and unfavourably associated with other reproduction traits such as litter size, which makes the development of optimal breeding strategies a challenge. To identify the optimum selection strategy for piglet survival, a selection experiment was carried out to compare responses in survival and reproduction traits to selection on only direct, only maternal, or both genetic effects of postnatal survival. The data of the experiment were recorded from outdoor reared pigs, with first- and second-generation sires selected based on their estimated breeding values for maternal and direct effects of postnatal survival of indoor reared offspring, respectively, with the opportunity to identify potential genotype-by-environment interaction. A Bayesian multivariate threshold-linear model that was fitted to data on 22,483 piglets resulted in significant (Pr(h2 > 0) = 1.00) estimates of maternal and direct heritabilities between 0.12 and 0.18 for survival traits and between 0.29 and 0.36 for birth weight, respectively. Selection for direct genetic effects resulted in direct and maternal responses in postnatal survival of 1.11% ± 0.17 and − 0.49% ± 0.10, respectively, while selection for maternal genetic effects led to greater direct and maternal responses, of 5.20% ± 0.34 and 1.29% ± 0.20, respectively, in part due to unintentional within-litter selection. Selection for both direct and maternal effects revealed a significant lower direct response (− 1.04% ± 0.12) in comparison to its expected response from single-effect selection, caused by interactions between direct and maternal effects. Selection successfully improved post- and perinatal survival and birth weight, which indicates that they are genetically determined and that genotype-by-environment interactions between outdoor (experimental data) and indoor (selection data) housed pigs were not important for these traits. A substantially increased overall (direct plus maternal) response was obtained using selection for maternal versus direct or both direct and maternal effects, suggesting that the maternal genetic effects are the main limiting factor for improving piglet survival on which selection pressure should be emphasized.

中文翻译：

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在选择实验中，基于不同的产后仔猪存活选择策略，评估繁殖性状的直接反应和母体反应

产后仔猪的存活对于经济和动物福利而言都很重要。它受到仔猪自身直接遗传效应和母猪母体遗传效应的影响，与产奶量和母性能力相关。这些遗传效应可能是相关的，受到其他非遗传因素的影响，并且与其他繁殖性状（例如窝产仔数）不利地相关，这使得制定最佳育种策略成为一项挑战。为了确定仔猪存活的最佳选择策略，进行了选择实验，以比较存活和繁殖性状对仅直接、仅母性或两种产后存活遗传效应的选择的反应。实验数据是从室外饲养的猪中记录的，第一代和第二代公猪分别根据其对母猪的估计育种值和室内饲养后代产后生存的直接影响进行选择，从而有机会识别潜在的基因型。环境相互作用。贝叶斯多元阈值线性模型拟合了 22,483 头仔猪的数据，结果显示母体遗传力和直接遗传力的显着估计值 (Pr(h2 > 0) = 1.00) 在 0.12 和 0.18 之间，生存性状和出生体重在 0.29 和 0.36 之间，分别。选择直接遗传效应导致产后存活率的直接反应和母体反应分别为 1.11% ± 0.17 和 − 0.49% ± 0.10，而选择母体遗传效应则导致更大的直接反应和母体反应，分别为 5.20% ± 0.34 和 1.29%分别为 ± 0.20，部分原因是无意的窝内选择。直接效应和母体效应的选择显示，与单效应选择的预期响应相比，直接响应显着降低（− 1.04% ± 0.12），这是由直接效应和母体效应之间的相互作用造成的。选择成功地提高了产后和围产期的存活率和出生体重，这表明它们是由基因决定的，并且室外（实验数据）和室内（选择数据）圈养猪之间基因型与环境的相互作用对于这些性状并不重要。使用母体与直接或直接和母体效应的选择获得了显着增加的总体（直接加母体）反应，这表明母体遗传效应是提高仔猪存活率的主要限制因素，应强调选择压力。