Understanding ruminal microbiota and diet-host breed interactions under forage feeding conditions is essential for optimizing rumen fermentation and improving feed efficiency in small ruminants. This study aimed to investigate the effects of different ratios of condensed tannin (CT)-rich Sericea lespedeza (Lespedeza cuneate) in the diets on changes and interactions of ruminal microbiota and host species (i.e., sheep and goats). Katahdin sheep (n = 12) and Alpine goats (n = 12) at approximately 10 to 12 months of age were blocked by body weight (BW = 30.3 kg and 25.5 kg, respectively) and randomly assigned to one of the three treatments. Diets contained 75% coarsely ground forage and 25% concentrate. The forages were (1) 100% alfalfa hay (AL), (2) 100% Sericea lespedeza hay (SL), and (3) 50 % AL + 50% SL (ASL). In the present study, the diversity and composition of ruminal microbiota differed between sheep and goats fed similar diets. Based on the taxonomic analysis, there was a distinct clustering pattern (P < 0.05) for sheep by diets, but such a pattern was not observed for goats (P > 0.1). The most predominant phyla were Firmicutes, Bacteroidetes, Ascomycota, and methanogen species of Methanobrevibactor sp. in the rumen of sheep and goats, regardless of diets. The Bacteroidetes and Ascomycota were enriched in sheep fed AL and ASL. In contrast, these microbial phyla were enhanced in goats fed tannin-rich SL diets, with the diet by host species interaction (P < 0.02) for the Bacteroidetes phylum. Sheep rumen fluid samples showed a higher degree of variability in microbial community composition compared to goat rumen fluid samples. The relative proportion of the Aspergillus fungi population was reduced to 90.7% in the SL group compared with the AL group, regardless of host species. The antimicrobial activity of tannins and greater sensitivities of selected microbiota species to these tannin compounds during SL feeding in sheep and goats perhaps caused this difference. The results from this study suggest that differences in the microbiota were associated with differences in diets and host species. Therefore, this study provides a better understanding of ruminal microbiota and diet-host species interactions under various tannin-rich diets, which could advance consolidative information on rumen microbiome community diversity changes and may improve sheep and goat production.

中文翻译：

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饲喂不同水平富含单宁的胡枝子干草的绵羊和山羊的瘤胃微生物群特征


了解饲料喂养条件下的瘤胃微生物群和饮食与宿主品种的相互作用对于优化小型反刍动物的瘤胃发酵和提高饲料效率至关重要。本研究旨在探讨日粮中不同比例的富含缩合单宁（CT）的胡枝子（Lespedeza cuneate）对瘤胃微生物群和宿主物种（即绵羊和山羊）的变化和相互作用的影响。将约 10 至 12 个月大的卡塔丁绵羊 (n = 12) 和高山山羊 (n = 12) 按体重分组（体重分别为 30.3 kg 和 25.5 kg），并随机分配至三种处理之一。日粮中含有 75% 的粗磨饲料和 25% 的精料。饲料为 (1) 100% 苜蓿干草 (AL)、(2) 100% 胡枝子干草 (SL) 和 (3) 50% AL + 50% SL (ASL)。在本研究中，饲喂相似饮食的绵羊和山羊的瘤胃微生物群的多样性和组成存在差异。根据分类学分析，绵羊的饮食存在明显的聚类模式 (P < 0.05)，但山羊没有观察到这种模式 (P > 0.1)。最主要的门是厚壁菌门、拟杆菌门、子囊菌门和产甲烷菌门 Methanobrevibactor sp。在绵羊和山羊的瘤胃中，无论饮食如何。拟杆菌门和子囊菌门在饲喂 AL 和 ASL 的羊中富集。相比之下，这些微生物门在饲喂富含单宁的 SL 日粮的山羊中得到增强，饮食与拟杆菌门的宿主物种相互作用 (P < 0.02)。与山羊瘤胃液样品相比，绵羊瘤胃液样品的微生物群落组成具有更高程度的变异性。曲霉属真菌种群的相对比例减少至90。与 AL 组相比，SL 组为 7%，无论宿主物种如何。单宁的抗菌活性以及在绵羊和山羊 SL 喂养期间选定的微生物群对这些单宁化合物的更高敏感性可能导致了这种差异。这项研究的结果表明，微生物群的差异与饮食和宿主物种的差异有关。因此，这项研究可以更好地了解各种富含单宁的日粮下的瘤胃微生物群和日粮与宿主物种的相互作用，这可以推进瘤胃微生物群落多样性变化的综合信息，并可能提高绵羊和山羊的产量。