Milk yield and fine composition in sheep depend on the volatile and long-chain fatty acids, microbial proteins, vitamins produced through feedstuff digestion by the rumen microbiota. In cattle, the host genome has been shown to have a low to moderate genetic control on rumen microbiota abundance but a high control on dairy traits with heritabilities higher than 0.30. There is little information on the genetic correlations and quantitative trait loci (QTL) that simultaneously affect rumen microbiota abundance and dairy traits in ruminants, especially in sheep. Thus, our aim was to quantify the effect of the host genetics on rumen bacterial abundance and the genetic correlations between rumen bacterial abundance and several dairy traits, and to identify QTL that are associated with both rumen bacterial abundance and milk traits. Our results in Lacaune sheep show that the heritability of rumen bacterial abundance ranges from 0 to 0.29 and that the heritability of 306 operational taxonomic units (OTU) is significantly different from 0. Of these 306 OTU, 96 that belong mainly to the Prevotellaceae, Lachnospiraceae and Ruminococcaceae bacterial families show strong genetic correlations with milk fatty acids and proteins (absolute values ranging from 0.33 to 0.99). Genome-wide association studies revealed a QTL for alpha-lactalbumin concentration in milk on Ovis aries chromosome (OAR) 11, and six QTL for rumen bacterial abundances i.e., for two OTU belonging to the genera Prevotella (OAR3 and 5), Rikeneleaceae_RC9_gut_group (OAR5), Ruminococcus (OAR5), an unknown genus of order Clostridia UCG-014 (OAR10), and CAG-352 (OAR11). None of these detected regions are simultaneously associated with rumen bacterial abundance and dairy traits, but the bacterial families Prevotellaceae, Lachnospiraceae and F082 show colocalized signals on OAR3, 5, 15 and 26. In Lacaune dairy sheep, rumen microbiota abundance is partially controlled by the host genetics and is poorly genetically linked with milk protein and fatty acid compositions, and three main bacterial families, Prevotellaceae, Lachnospiraceae and F082, show specific associations with OAR3, 5, 15 and 26.

中文翻译：

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宿主对瘤胃微生物群的遗传控制及其对绵羊乳品性状的影响

绵羊的产奶量和精细成分取决于瘤胃微生物群通过饲料消化产生的挥发性和长链脂肪酸、微生物蛋白质和维生素。在牛中，宿主基因组已被证明对瘤胃微生物群丰度具有低到中度的遗传控制，但对遗传力高于 0.30 的乳制品性状具有高度控制。关于同时影响反刍动物（尤其是绵羊）瘤胃微生物群丰度和乳品性状的遗传相关性和数量性状基因座 (QTL) 的信息很少。因此，我们的目标是量化宿主遗传学对瘤胃细菌丰度的影响以及瘤胃细菌丰度与几种乳品性状之间的遗传相关性，并确定与瘤胃细菌丰度和牛奶性状相关的 QTL。我们在 Lacaune 绵羊中的结果表明，瘤胃细菌丰度的遗传力范围为 0 到 0.29，并且 306 个操作分类单元 (OTU) 的遗传力与 0 有显着差异。在这 306 个 OTU 中，96 个主要属于 Prevotellaceae、Lachnospiraceae和瘤胃球菌科细菌家族与乳脂肪酸和蛋白质表现出很强的遗传相关性（绝对值范围从 0.33 到 0.99）。全基因组关联研究揭示了绵羊白羊座染色体 (OAR) 11 上牛奶中 α-乳白蛋白浓度的 QTL，以及瘤胃细菌丰度的六个 QTL，即属于 Prevotella 属（OAR3 和 5）的两个 OTU，Rikeneleaceae_RC9_gut_group（OAR5 )、瘤胃球菌 (OAR5)、梭状芽孢杆菌 UCG-014 (OAR10) 和 CAG-352 (OAR11) 的未知属。