National Livestock Breeding Center, Nishigo, Japan.
NARO Institute of Livestock and Grassland Science, Tsukuba, Japan.
J Anim Breed Genet. 2021 Jan;138(1):45-55. doi: 10.1111/jbg.12493. Epub 2020 Aug 2.
Genomic imprinting should be considered in animal breeding systems to avoid lead in bias in genetic parameter estimation. The objective of this study was to clarify the effects of pedigree information on imprinting variances for carcass traits and fatty acid composition in Japanese Black cattle. Carcass records [carcass weight, rib eye area, rib thickness (RT), subcutaneous fat thickness and beef marbling score (BMS)] and fatty acid composition were obtained for 11,855 Japanese Black feedlot cattle. To estimate and compare the imprinting variances for the traits, two imprinting models with different pedigree information [the sire-dam gametic relationship matrix (Model 1) and the sire-maternal grandsire (MGS) numerator relationship matrix (Model 2)] were fitted. The ratio of the imprinting variance to the total additive genetic variance for RT (6.33%) and BMS (19.00%) was significant in Model 1, but only that for BMS (21.09%) was significant in Model 2. This study revealed that fitting the sire-MGS model could be useful in estimating imprinting variance under certain conditions, such as when restricted pedigree information is available. Furthermore, the present result suggested that the maternal gametic effects on BMS should be included in breeding programmes for Japanese Black cattle to avoid selection bias caused by imprinting effects.
在动物育种系统中应考虑基因组印迹，以避免遗传参数估计中的铅偏差。本研究的目的是阐明系谱信息对日本黑牛胴体性状和脂肪酸组成印迹方差的影响。为 11855 头日本黑牛育肥场牛获得了胴体记录[胴体重、眼肌面积、肋骨厚度（RT）、皮下脂肪厚度和牛肉大理石花纹评分（BMS）]和脂肪酸组成。为了估计和比较性状的印迹方差，使用两种具有不同系谱信息的印迹模型[父本-母本配子关系矩阵（模型 1）和父本-母本-祖父（MGS）分子关系矩阵（模型 2）]拟合印迹方差。在模型 1 中，RT（6.33%）和 BMS（19.00%）的印迹方差与总加性遗传方差的比值显著，但在模型 2 中仅 BMS（21.09%）的比值显著。本研究表明，在某些情况下，如可用限制系谱信息时，拟合父本-MGS 模型可能有助于估计印迹方差。此外，本研究结果表明，在日本黑牛的育种计划中应包括母本配子对 BMS 的影响，以避免由印迹效应引起的选择偏差。
