This study investigated the effects of inulin on rumen fermentation parameters, ruminal microbiome and metabolites, as well as lactation performance and serum indexes in dairy cows. Sixteen Holstein dairy cows with similar body conditions were randomly divided into 2 groups (n = 8 per group), with inulin addition at 0 and 200 g/d per cow. The experiment lasted for 6 weeks, including a 1-week adaptation period and a 5-week treatment period. At the end of the experimental period, the milk, serum and rumen fluid were sampled and analyzed. The microbiome and metabolome in the rumen fluid were analyzed via 16S rRNA sequencing and untargeted metabolomics, respectively. The results showed that supplementation with inulin (200 g/d per cow) increased the milk yield (P = 0.001), milk protein (P = 0.032), lactose rate (P = 0.004) and proportion of saturated fatty acids (SFA) in milk (P < 0.001), but decreased the proportion of unsaturated fatty acids (USFA) (P = 0.041). Rumen pH (P = 0.040) and the concentration of NH₃–N (P = 0.024) were decreased; however, acetate (P < 0.001), propionate (P = 0.003), butyrate (P < 0.001) and lactic acid (LA) (P = 0.043) were increased. The total cholesterol (TC) (P = 0.008) and triglycerides (TG) (P = 0.01) in serum were also reduced. Additionally, inulin addition elevated the relative abundance of several beneficial symbiotic and short-chain fatty acid (SCFA)-producing bacteria, such as Muribaculaceae (false discovery rate [FDR]-adjusted P < 0.01), Acetitomaculum (FDR-adjusted P = 0.043), and Butyrivibrio (FDR-adjusted P = 0.036), while elevating the levels of L-lysine (FDR-adjusted P = 4.24 × 10⁻³), L-proline (FDR-adjusted P = 0.0158), and L-phenylalanine (FDR-adjusted P = 0.027). In contrast, several pathogens and ruminal bacteria abundant in high-fat diets, such as Escherichia-Shigella (FDR-adjusted P = 0.022), Erysipelotrichaceae__UCG-004 (FDR-adjusted P < 0.01) and RF39 (FDR-adjusted P = 0.042) were decreased along with the reduction of lysophosphatidylcholine (LysoPC) (18:1 (9Z)) (FDR-adjusted P = 1.03 × 10⁻³), LysoPC (16:0) (FDR-adjusted P = 0.0108), LysoPC (18:2 (9Z, 12Z)) (FDR-adjusted P = 1.65 × 10⁻³) and 8-methylnonenoate. In conclusion, dietary inulin supplementation could increase the relative abundance of commensal microbiota and SCFA-producing bacteria, upregulate amino acidmetabolism and downregulate lipid metabolism in the rumen of dairy cows, which might further improve lactation performance and the level of serum lipids.

本研究调查了菊粉对奶牛瘤胃发酵参数、瘤胃微生物组和代谢物以及泌乳性能和血清指标的影响。将 16 头体况相似的荷斯坦奶牛随机分为 2 组（每组n  = 8），每头奶牛添加菊粉 0 和 200 g/d。实验持续6周，包括1周的适应期和5周的治疗期。实验结束时，对牛奶、血清和瘤胃液进行取样分析。瘤胃液中的微生物组和代谢组分别通过 16S rRNA 测序和非靶向代谢组学进行分析。结果表明，添加菊粉（每头奶牛 200 g/d）可提高产奶量（P  = 0.001）、乳蛋白（P  = 0.032）、乳糖率（P  = 0.004）和牛奶中饱和脂肪酸（SFA） 的比例（P < 0.001），但不饱和脂肪酸（USFA）的比例降低（P  = 0.041）。瘤胃 pH ( P  = 0.040) 和 NH ₃ –N ( P  = 0.024) 浓度降低；然而，乙酸盐 ( P  < 0.001)、丙酸盐 ( P  = 0.003)、 丁酸盐 ( P  < 0.001) 和乳酸 (LA) ( P  = 0.043) 增加。总胆固醇 (TC) ( P  = 0.008) 和甘油三酯 (TG) ( P = 0.01) 在血清中也降低了。此外，菊粉的添加提高了几种有益的共生和短链脂肪酸 (SCFA) 产生细菌的相对丰度，例如Muribaculaceae（错误发现率 [FDR] 调整的P  < 0.01）、Acetitomaculum（FDR 调整的P  = 0.043 ) 和Butyrivibrio（经 FDR 调整的P  = 0.036），同时提高 L-赖氨酸（经 FDR 调整的P  = 4.24 × 10 ^-3）、L-脯氨酸（经 FDR 调整的P  = 0.0158）和 L-苯丙氨酸的水平（FDR 调整后的P  = 0.027）。相比之下，高脂肪饮食中富含的几种病原体和瘤胃细菌，例如大肠杆菌-志贺氏菌（经 FDR 调整的P  = 0.022）、丹毒杆菌科 __UCG-004（经 FDR 调整的P  < 0.01）和RF39（经 FDR 调整的P  = 0.042）随着溶血磷脂酰胆碱（18:11so 9Z)) (FDR 调整P  = 1.03 × 10 ^-3 )、LysoPC (16:0) (FDR 调整P  = 0.0108)、LysoPC (18:2 (9Z, 12Z)) (FDR 调整P  = 1.65 × 10 ^-3) 和 8-壬烯酸甲酯。综上所述，日粮添加菊粉可增加奶牛瘤胃共生微生物群和产SCFA细菌的相对丰度，上调氨基酸代谢，下调奶牛瘤胃脂质代谢，进一步改善泌乳性能和血脂水平。