Department of Animal Sciences, University of Florida, Gainesville, FL, United States of America.
DH Barron Reproductive and Perinatal Biology Research Program, University of Florida, Gainesville, FL, United States of America.
PLoS One. 2023 Oct 5;18(10):e0290562. doi: 10.1371/journal.pone.0290562. eCollection 2023.
Objectives were to determine the effects of supplementing increasing amounts of choline ion on hepatic composition and mRNA abundance in pregnant dry cows subjected to a fatty liver induction protocol. Holstein cows (35 primiparous and 41 multiparous) at mean (± standard deviation) of 211 ± 9.9 days of gestation were blocked by body condition (3.59 ± 0.33) and assigned to receive 0, 6.45, 12.90, 19.35, and 25.80 g/day of choline ion as rumen-protected choline (RPC) as a top-dress for 14 days. Cows were fed for ad libitum intake on days 1 to 5 and restricted to 30% of the required net energy for lactation from days 6 to 14 of the experiment. Hepatic tissue was sampled on days 5 and 14 and analyzed for concentrations of triacylglycerol and glycogen, and mRNA abundance was investigated. Orthogonal contrasts evaluated the effects of supplementing RPC (0 g/day vs. rest), and the linear, quadratic, and cubic effects of increasing intake of choline ion from 6.45 to 25.80 g/day. Results are depicted in sequence of treatments from 0 to 25.8. During feed restriction, RPC reduced the concentration of hepatic triacylglycerol by 28.5% and increased that of glycogen by 26.1%, and the effect of increasing RPC intake on triacylglycerol was linear (6.67 vs. 5.45 vs. 4.68 vs. 5.13 vs. 3.81 ± 0.92% wet-basis). Feeding RPC during feed restriction increased abundance of transcripts involved in choline metabolism (CHKA, PLD1), synthesis of apolipoprotein-B100 (APOB100), and antioxidant activity (GPX3), and decreased the abundance of transcripts involved in hepatic lipogenesis (DGAT2, SREBF1) and acute phase response (SAA3). Most effects were linear with amount of choline fed. Changes in hepatic mRNA abundance followed a pattern of reduced lipogenesis and enhanced lipids export, which help explain the reduced hepatic triacylglycerol content in cows fed RPC. Choline exerts lipotropic effects in dairy cows by altering transcript pathways linked to hepatic lipids metabolism.
目的在于确定在经历脂肪肝诱导方案的妊娠干奶牛中，补充不同剂量胆碱离子对肝脏成分和 mRNA 丰度的影响。选择平均（±标准差）妊娠 211±9.9 天的荷斯坦奶牛（35 头初产牛和 41 头经产牛），根据体况（3.59±0.33）进行分组，并被分配至接受 0、6.45、12.90、19.35 和 25.80 g/天的胆碱离子作为瘤胃保护性胆碱（RPC）作为 14 天的顶部饲料。在第 1 至 5 天，奶牛自由采食，在实验的第 6 至 14 天，奶牛限制采食 30%的泌乳所需净能。在第 5 天和第 14 天采集肝脏组织，并分析三酰甘油和糖原的浓度，同时研究 mRNA 丰度。正交对比评估了补充 RPC（0 g/天与其余组）以及从 6.45 至 25.80 g/天的胆碱离子摄入量增加的线性、二次和三次效应的影响。结果按从 0 至 25.8 的处理顺序呈现。在饲料限制期间，RPC 降低了肝脏三酰甘油的浓度 28.5%，增加了糖原的浓度 26.1%，并且增加 RPC 摄入量对三酰甘油的影响呈线性（6.67 比 5.45 比 4.68 比 5.13 比 3.81±0.92%湿基）。在饲料限制期间补充 RPC 增加了与胆碱代谢（CHKA、PLD1）、载脂蛋白-B100（APOB100）合成以及抗氧化活性（GPX3）相关的转录本的丰度，并降低了与肝脏脂肪生成（DGAT2、SREBF1）和急性期反应（SAA3）相关的转录本的丰度。大多数影响呈线性关系，与所提供的胆碱量有关。肝脏 mRNA 丰度的变化遵循减少脂肪生成和增强脂质输出的模式，这有助于解释在饲喂 RPC 的奶牛中肝脏三酰甘油含量降低的原因。胆碱通过改变与肝脏脂质代谢相关的转录途径，在奶牛中发挥脂肪作用。
