Objectives were to determine the effects of supplementing rumen‐protected choline (RPC) from an established source with low (L, 28.8%) or a prototype with less lipid coating protection and high (H, 60.0%) concentrations of choline chloride on digestibility of fat and supra‐mammary lymph metabolome in feed‐restricted cows. Pregnant, nonlactating Holstein cows (n = 33; 11/treatment) at mean (±standard deviation) 231 ± 4.7 days of gestation were blocked by body condition (4.23 ± 0.47) and assigned to receive 0 (CON) or 25.8 g/d of choline ion from L (L25.8) or H (H25.8). Cows were adapted to the diet and then fed‐restricted to 42% of the net energy of lactation required for maintenance and pregnancy for 9 days. Intake of metabolizable methionine was maintained at 19 g/d. On Day 9, cows were fed 450 g of saturated fatty acids (SFA), and feces and blood were sampled continuously for 24 h. Supra‐mammary lymph was sampled 6 h after feeding SFA and metabolome was characterized. Feeding RPC increased digestibility of fat (CON = 80.4 vs. RPC = 86.0 ± 1.9%) and reduced the concentration of haptoglobin in serum (CON = 174 vs. RPC = 77 ± 14 µg/ml) independent of source of RPC fed. Feeding RPC increased the concentrations of triacylglycerol in serum (CON = 15.1 vs. RPC = 17.8 ± 1.9 mg/dl) in feed‐restricted cows after feeding SFA, and the increment tended to be greater for cows fed H25.8 than L25.8. Supplementing RPC tended to increase the concentrations of triacylglycerol (CON = 11.4 vs. RPC = 15.8 ± 3.4 mg/dl) in supra‐mammary lymph. Feeding RPC increased the concentration of choline and affected the concentrations of analytes involved in metabolic pathways associated with amino acid metabolism and biosynthesis of phospholipids in lymph compared with CON. Feeding RPC, independent of source used, increased fat digestibility with some changes in lymph metabolome in cows under negative nutrient balance.

中文翻译：

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瘤胃保护胆碱对奶牛脂肪消化率和淋巴代谢组的影响

目的是确定补充低浓度（L，28.8％）或脂质涂层保护较少的原型和高浓度（H，60.0％）氯化胆碱的既定来源的瘤胃保护胆碱（RPC）对瘤胃消化率的影响限制饲喂奶牛的脂肪和乳上淋巴代谢组。怀孕、非泌乳荷斯坦奶牛（n= 33；11/治疗）在平均（±标准偏差）妊娠231±4.7天时因身体状况（4.23±0.47）而被阻断，并被分配接受0（CON）或25.8g/d来自L（L25.8）的胆碱离子或 H (H25.8)。奶牛适应了饮食，然后在 9 天的时间内将饲喂量限制为维持和妊娠所需泌乳净能量的 42%。可代谢蛋氨酸的摄入量维持在19克/天。第9天，饲喂450克饱和脂肪酸（SFA），连续24小时采集粪便和血液样本。饲喂 SFA 后 6 小时对乳上淋巴进行取样，并对代谢组进行表征。饲喂 RPC 会增加脂肪的消化率（CON = 80.4 对比 RPC = 86.0 ± 1.9%），并降低血清中触珠蛋白的浓度（CON = 174 对比 RPC = 77 ± 14 µg/ml），与饲喂 RPC 的来源无关。饲喂 RPC 会增加饲喂 SFA 后限饲奶牛血清中三酰甘油的浓度（CON = 15.1 vs. RPC = 17.8 ± 1.9 mg/dl），且饲喂 H25.8 的奶牛的增量往往大于饲喂 L25.8 的奶牛。 。补充 RPC 往往会增加乳上淋巴中三酰甘油的浓度（CON = 11.4 对比 RPC = 15.8 ± 3.4 mg/dl）。与 CON 相比，饲喂 RPC 增加了胆碱的浓度，并影响了与氨基酸代谢和淋巴中磷脂生物合成相关的代谢途径所涉及的分析物的浓度。饲喂 RPC（与所用来源无关）可提高脂肪消化率，并在营养负平衡条件下使奶牛的淋巴代谢组发生一些变化。