Agriculture and Agri-Food Canada, Edmonton, AB T6G 2C8, Canada.
Department of Agriculture, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada.
J Anim Sci. 2021 May 1;99(5). doi: 10.1093/jas/skab140.
Discovery of epigenetic modifications associated with feed efficiency or other economically important traits would increase our understanding of the molecular mechanisms underlying these traits. In combination with known genetic markers, this would provide opportunity to improve genomic selection accuracy in cattle breeding programs. It would also allow cattle to be managed to improve favorable gene expression. The objective of this study was to identify variation in DNA methylation between beef cattle of differential pre-natal nutrition and divergent genetic potential for residual feed intake (RFI). Purebred Angus offspring with the genetic potential for either high (HRFI) or low (LRFI) RFI were prenatally exposed to either a restricted maternal diet of 0.5 kg/d average daily gain (ADG) or a moderate maternal diet of 0.7 kg/d ADG from 30 to 150 d of gestation. We performed DNA methylation analysis of differentially methylated regions (DMR) of imprinted genes (Insulin-like growth factor 2 (IGF2) DMR2, IGF2/H19 imprinting control region (ICR) and IGF2 receptor (IGF2R) DMR2) using post-natal samples of longissimus dorsi (LD) muscle taken from male and female calves at birth and weaning, and of LD muscle, semimembranosus (SM) muscle, and liver samples collected from steers at slaughter (17 months of age). Interestingly, for all three DMR investigated in liver, LRFI steers had higher levels of methylation than HRFI steers. In LD muscle, IGF2/H19 ICR methylation differences for heifers at birth were due to pre-natal diet, while for steers at birth they were mostly the result of genetic potential for RFI with LRFI steers again having higher levels of methylation than HRFI steers. While results from repeated measures analysis of DNA methylation in steers grouped by RFI revealed few differences, in steers grouped by diet, we found higher methylation levels of IGF2 DMR2 and IGF2R DMR2 in LD muscle of restricted diet steers at weaning and slaughter than at birth, as well as increased methylation in LD muscle of restricted diet steers compared with moderate diet steers at weaning and/or slaughter. Our results suggest that differential pre-natal nutrition, and divergent genetic potential for RFI, induces tissue- and sex-specific alterations in post-natal IGF2 and IGF2R methylation patterns and that these patterns can vary with age in Angus beef cattle.
发现与饲料效率或其他经济重要性状相关的表观遗传修饰，将增加我们对这些性状基础分子机制的理解。结合已知的遗传标记，这将为牛的育种计划提供提高基因组选择准确性的机会。它还可以让牛得到管理，以改善有利的基因表达。本研究的目的是鉴定不同产前营养和不同剩余饲料摄入（RFI）遗传潜力的肉牛之间 DNA 甲基化的差异。具有高（HRFI）或低（LRFI）RFI 遗传潜力的纯种安格斯后代，从妊娠 30 天到 150 天，产前接受 0.5 公斤/天平均日增重（ADG）的限制母体饮食或 0.7 公斤/天 ADG 的适度母体饮食。我们对出生和断奶时雄性和雌性犊牛的背最长肌（LD）、LD 肌肉、半膜肌（SM）肌肉和阉牛屠宰时采集的肝脏样本中差异甲基化区域（DMR）的印记基因（胰岛素样生长因子 2（IGF2）DMR2、IGF2/H19 印迹控制区（ICR）和 IGF2 受体（IGF2R）DMR2）进行了 DNA 甲基化分析。有趣的是，对于所有在肝脏中研究的三个 DMR，LRFI 阉牛的甲基化水平高于 HRFI 阉牛。在 LD 肌肉中，出生时小母牛 IGF2/H19 ICR 甲基化差异是由于产前饮食，而对于出生时的阉牛，主要是由于 RFI 的遗传潜力，LRFI 阉牛的甲基化水平再次高于 HRFI 阉牛。虽然根据 RFI 分组的牛的 DNA 甲基化重复测量分析结果显示差异很少，但根据饮食分组的牛，我们发现限制饮食的阉牛在断奶和屠宰时 LD 肌肉的 IGF2 DMR2 和 IGF2R DMR2 甲基化水平高于出生时，并且限制饮食的阉牛与适度饮食的阉牛相比，在断奶和/或屠宰时 LD 肌肉的甲基化水平增加。我们的结果表明，不同的产前营养和不同的 RFI 遗传潜力，导致 Angus 肉牛出生后 IGF2 和 IGF2R 甲基化模式的组织和性别特异性改变，并且这些模式可以随着年龄的增长而变化。
