The objective of this study was to explore the relationships between ruminal microbial populations from Angus steers that were divergent in carcass traits related to adipose accumulation. Twenty-four feedlot-finished Angus steers (Age: 538 ± 21 d; BW following lairage: 593.9 ± 43.7 kg) were slaughtered, and ruminal contents and carcass data were collected. Ruminal microbial DNA extraction and 16S rRNA gene sequencing were performed to determine microbial relative abundances, estimate microbial diversity, and to predict microbial metabolic pathways. A variety of correlation analyses and one-way ANOVA were performed to investigate the relationships between the rumen microbiome and carcass traits. Marbling score (P = 0.001) and longissimus lipid content (P = 0.009) were positively correlated to Chao1 Richness Index, suggesting that increased intramuscular fat was associated with increased numbers of ruminal microbial species. The phyla Tenericutes and TM7 were negatively correlated (P ≤ 0.05) to marbling score and longissimus lipid content, indicating that lower abundances of these phyla may be associated with improvements in intramuscular fat content. Greater abundance of the bacterial family S24-7 was positively correlated (P = 0.002) to marbling score. Analysis by marbling classification revealed further linkages to microbial richness (P ≤ 0.063), diversity (P = 0.044), and S24-7 (P & 0.001) populations. Computational prediction of the microbial metabolic pathways revealed no differences (P ≥ 0.05) in metabolic pathway expression in rumen microbes between steers in the high- and low-marbling classes. Several phyla, families, and genera were positively correlated (P ≤ 0.05) to both rib fat thickness and yield grade. Collectively, our results suggest that microbial composition is associated to differing performance in carcass adipose traits. Overall, most of the bacterial taxa correlated to the intramuscular and subcutaneous fat depots did not overlap, suggesting the microbial population end-products likely impacted adipose accumulation largely via separate adipogenic pathways of the host animal.

中文翻译：

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安格斯阉牛瘤胃微生物组与胴体品质之间的关系。


本研究的目的是探讨安格斯小公牛瘤胃微生物种群之间的关系，这些微生物种群在与脂肪积累相关的胴体性状方面存在差异。屠宰 24 头饲养场育成的安格斯公牛（年龄：538 ± 21 天；圈养后体重：593.9 ± 43.7 kg），收集瘤胃内容物和屠体数据。进行瘤胃微生物 DNA 提取和 16S rRNA 基因测序以确定微生物相对丰度、估计微生物多样性并预测微生物代谢途径。进行了多种相关性分析和单向方差分析来研究瘤胃微生物组与胴体性状之间的关系。大理石花纹评分（ P = 0.001）和最长肌脂质含量（ P = 0.009）与Chao1丰富度指数呈正相关，表明肌内脂肪增加与瘤胃微生物种类数量增加相关。 Tenericutes 门和 TM7 门与大理石花纹评分和最长肌脂质含量呈负相关（ P ≤ 0.05），表明这些门的丰度较低可能与肌内脂肪含量的改善有关。细菌家族 S24-7 的丰度与大理石花纹得分呈正相关 ( P = 0.002)。大理石花纹分类分析揭示了与微生物丰富度 ( P ≤ 0.063)、多样性 ( P = 0.044) 和 S24-7 ( P & 0.001) 种群的进一步联系。微生物代谢途径的计算预测显示，高大理石花纹等级和低大理石花纹等级的阉牛之间的瘤胃微生物代谢途径表达没有差异（ P≥0.05 ）。 一些门、科、属与肋骨脂肪厚度和产量等级均呈正相关（ P≤0.05 ）。总的来说，我们的结果表明微生物组成与胴体脂肪性状的不同表现相关。总体而言，大多数与肌内和皮下脂肪库相关的细菌分类群并不重叠，这表明微生物群体的最终产物可能主要通过宿主动物单独的脂肪形成途径影响脂肪积累。