During the transition period, excessive negative energy balance (NEB) lead to metabolic disorders and reduced milk yield. Rumen microbes are responsible for resolving plant material and producing volatile fatty acids (VFA), which are the primary energy source for cows. In this study, we aimed to investigate the effect of citrus peel extract (CPE) supplementation on rumen microbiota composition, energy metabolism and milk performance of peripartum dairy cows. Dairy cows were fed either a basal diet (CON group) or the same basal diet supplemented with CPE via intragastric administration (4 g/d, CPE group) for 6 weeks (3 weeks before and 3 weeks after calving; n = 15 per group). Samples of serum, milk, rumen fluid, adipose tissue, and liver were collected to assess the effects of CPE on rumen microbiota composition, rumen fermentation parameters, milk performance, and energy metabolic status of dairy cows. CPE supplementation led to an increase in milk yield, milk protein and lactose contents, and serum glucose levels, while reduced serum concentrations of non-esterified fatty acid, β-hydroxybutyric acid, insulin, aspartate aminotransferase, alanine aminotransferase, and haptoglobin during the first month of lactation. CPE supplementation also increased the content of ruminal VFA. Compared to the CON group, the abundance of Prevotellaceae, Methanobacteriaceae, Bacteroidales_RF16_group, and Selenomonadaceae was found increased, while the abundance of Oscillospiraceae, F082, Ruminococcaceae, Christensenellaceae, Muribaculaceae UCG-011, Saccharimonadaceae, Hungateiclostridiaceae, and Spirochaetaceae in the CPE group was found decreased. In adipose tissue, CPE supplementation decreased lipolysis, and inflammatory response, while increased insulin sensitivity. In the liver, CPE supplementation decreased lipid accumulation, increased insulin sensitivity, and upregulated expression of genes involved in gluconeogenesis. Our findings suggest that CPE supplementation during the peripartum period altered rumen microbiota composition and increased ruminal VFA contents, which further improved NEB and lactation performance, alleviated lipolysis and inflammatory response in adipose tissue, reduced lipid accumulation and promoted gluconeogenesis in liver. Thus, CPE might contribute to improve energy metabolism and consequently lactation performance of dairy cows during the transition period.

中文翻译：

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在过渡期补充柑橘皮提取物可改善瘤胃微生物组成并改善奶牛的能量代谢和泌乳性能


在过渡期，过度的负能量平衡 （NEB） 会导致代谢紊乱和产奶量降低。瘤胃微生物负责分解植物材料并产生挥发性脂肪酸 （VFA），这是奶牛的主要能源。在本研究中，我们旨在研究柑橘皮提取物 （CPE） 补充剂对围产期奶牛瘤胃微生物群组成、能量代谢和产奶性能的影响。奶牛饲喂基础日粮 （CON 组） 或通过胃内给药补充 CPE 的相同基础日粮 （4 g/d，CPE 组） 持续 6 周 （产犊前 3 周和产犊后 3 周;每组 n = 15）。收集血清、牛奶、瘤胃液、脂肪组织和肝脏样品，以评估 CPE 对奶牛瘤胃菌群组成、瘤胃发酵参数、牛奶性能和能量代谢状态的影响。在泌乳期的第一个月，补充 CPE 导致产奶量、牛奶蛋白和乳糖含量以及血糖水平增加，同时降低非酯化脂肪酸、β-羟基丁酸、胰岛素、天冬氨酸氨基转移酶、丙氨酸氨基转移酶和结合珠蛋白的血清浓度。CPE 补充剂还增加了瘤胃 VFA 的含量。与 CON 组相比，Prevotellaceae、Methanobacteriaceae、Bacteroidales_RF16_group 和 Selenomonadaceae 的丰度增加，而 CPE 组的 Oscillospiraceae、F082、Ruminococcaceae、Christensenellaceae、Muribaculaceae UCG-011、Saccharimonadaceae、Hungateiclostridiaceae 和 Spirochaetaceae 的丰度降低。在脂肪组织中，补充 CPE 可降低脂肪分解和炎症反应，同时增加胰岛素敏感性。 在肝脏中，CPE 补充剂减少了脂质积累，增加了胰岛素敏感性，并上调了参与糖异生的基因表达。我们的研究结果表明，围产期补充 CPE 改变了瘤胃微生物群组成并增加了瘤胃 VFA 含量，从而进一步改善了 NEB 和泌乳性能，减轻了脂肪组织中的脂肪分解和炎症反应，减少了脂质积累并促进了肝脏中的糖异生。因此，CPE 可能有助于改善过渡期奶牛的能量代谢，从而提高奶牛的泌乳性能。