Residual feed intake (RFI) is a metric that provides a more accurate measure of feed efficiency. The lower the RFI, the higher the feed efficiency. The changes in the host microbiome and metabolome contribute to the greater feed efficiency of low RFI (LRFI) animals. The aim of this study was to explore the differences in rumen microorganisms, rumen metabolites and plasma metabolites of Hu sheep with differing RFI through the microbiome and metabolome. A total of 80 Hu sheep were used. The experiment consisted of a 15-d pretrial period and a 128-d experimental period. The RFI in the experimental period was calculated for all sheep, and the sheep were screened into high RFI (HRFI, n = 8) and LRFI (n = 8) groups. The HRFI and LRFI sheep did not differ in their initial and final body weights, average daily gain and body measurements, but the dry matter intake of LRFI sheep was significantly decreased (28.4%, P < 0.001). The sheep with LRFI had higher digestibility of crude protein (P = 0.010) and ether extract (P = 0.010) compared to HRFI group. The concentrations of acetate (P = 0.036), propionate (P = 0.010), valerate (P = 0.027) and total volatile fatty acids (P = 0.048) in rumen of LRFI group were higher compared to HRFI group. The results of 16S rDNA sequencing indicated that the sheep with LRFI had higher proportions of Prevotella genus in rumen liquid (P = 0.031). The rumen metabolome and plasma metabolome results showed that the citrate cycle, pyruvate metabolism and alanine, aspartate and glutamate metabolism processes were more active for sheep in LRFI group, which provided more energy substrate such as malic acid, oxoglutaric acid and citric acid. In conclusion, sheep with LRFI can utilize feed more efficiently, and the more active energy metabolism pathway and the production of energy substances may account for the higher feed efficiency.

中文翻译：

---

整合多组学揭示了不同残余采食量的胡羊生长性能、瘤胃微生物和代谢状态之间的关系


残余采食量 （RFI） 是一种更准确的饲料效率衡量指标。RFI 越低，进料效率越高。宿主微生物组和代谢组的变化有助于提高低 RFI （LRFI） 动物的饲料效率。本研究的目的是探讨通过微生物组和代谢组不同 RFI 的胡羊瘤胃微生物、瘤胃代谢物和血浆代谢物的差异。共使用了 80 只胡羊。实验包括 15 d 的预审期和 128 d 的实验期。计算所有绵羊在实验期间的 RFI，并将绵羊筛选为高 RFI （HRFI， n = 8） 和 LRFI （n = 8） 组。HRFI 和 LRFI 绵羊的初始和最终体重、平均日增重和身体测量值没有差异，但 LRFI 绵羊的干物质摄入量显着降低 （28.4%，P < 0.001）。与 HRFI 组相比，LRFI 绵羊粗蛋白 （P = 0.010） 和醚提取物 （P = 0.010） 的消化率更高。LRFI 组瘤胃中乙酸盐 （P = 0.036） 、丙酸盐 （P = 0.010） 、戊酸盐 （P = 0.027） 和总挥发性脂肪酸 （P = 0.048） 浓度高于 HRFI 组。16S rDNA 测序结果显示，LRFI 绵羊瘤胃液中普雷沃菌属比例较高 （P = 0.031）。瘤胃代谢组和血浆代谢组结果显示，LRFI 组绵羊柠檬酸循环、丙酮酸代谢和丙氨酸、天冬氨酸和谷氨酸代谢过程更活跃，提供了更多的苹果酸、氧代戊二酸和柠檬酸等能量底物。 总之，具有 LRFI 的绵羊可以更有效地利用饲料，更活跃的能量代谢途径和能量物质的产生可能是饲料效率更高的原因。