Guretzky N A Janovick, Carlson D B, Garrett J E, Drackley J K
Department of Animal Sciences, University of Illinois, Urbana, 61801, USA.
J Dairy Sci. 2006 Jan;89(1):188-200. doi: 10.3168/jds.S0022-0302(06)72083-5.
Choline is important for assembly of very low density lipoproteins to export triglyceride from liver; however, studies to assess the effect of rumen-protected choline (RPC) supplementation on blood lipid metabolites in periparturient dairy cows have not been conducted. Thirty-two multiparous Holstein and 10 multiparous Jersey cows were randomly assigned to control or RPC treatments. A close-up diet was fed from approximately 3 wk before parturition through parturition, followed by a lactation diet from parturition through 49 d postpartum. For RPC, diets were top-dressed once daily with 60 g of a RPC product (25% choline as choline chloride) from 21 d before expected parturition through 21 d postpartum. Treatment did not affect dry matter intake either prepartum (12.0 vs. 12.1 kg/d for RPC and control, respectively) or during the first 3 wk postpartum (14.8 vs. 15.7 kg/d, respectively). Daily yields of 3.5% fat-corrected milk (39.4 vs. 37.4 kg/d), fat (1.46 vs. 1.38 kg/d), and protein (1.09 vs. 1.05 kg/d) did not differ statistically by treatment (RPC vs. control, respectively). Jersey cows in the control group had lower concentrations of nonesterified fatty acids and beta-hydroxybutyrate in plasma during d 1 to 10 postpartum than did other breed and treatment combinations. Cows fed RPC tended to have greater serum triglycerides prepartum (17.0 vs. 14.7 mg/dL) and lower plasma phospholipid at parturition (65.2 vs. 78.1 mg/dL) than control cows. Treatment did not affect cholesterol and phospholipid at other time points, but concentrations followed patterns of dry matter intake pre- and postpartum. Cows were in moderate body condition score (mean = 3.3) at the start of the study and did not lose excessive condition by 3 wk postpartum (mean body condition score loss = 0.5); therefore, cows might not have been at great risk for hepatic lipid accumulation. Additionally, calculated Met balance was negative postpartum; supplemental RPC might not have spared enough Met to produce a physiological benefit. More research is needed to determine how choline affects prevention or alleviation of fatty liver syndrome and to confirm potential differences between Holstein and Jersey cows.
胆碱对于组装极低密度脂蛋白以从肝脏输出甘油三酯很重要；然而，尚未开展评估瘤胃保护性胆碱（RPC）补充剂对围产期奶牛血脂代谢物影响的研究。将32头经产荷斯坦奶牛和10头经产泽西奶牛随机分配至对照组或RPC处理组。从分娩前约3周直至分娩期间饲喂围产前期日粮，随后从分娩至产后49天饲喂泌乳期日粮。对于RPC处理组，从预计分娩前21天至产后21天，日粮每天一次额外添加60克RPC产品（25%的胆碱以氯化胆碱形式存在）。处理对产前干物质采食量（RPC组和对照组分别为12.0千克/天和12.1千克/天）或产后前3周的干物质采食量（分别为14.8千克/天和15.7千克/天）均无影响。3.5%乳脂校正乳的日产量（分别为39.4千克/天和37.4千克/天）、脂肪（分别为1.46千克/天和1.38千克/天）和蛋白质（分别为1.09千克/天和1.05千克/天）在处理组间（RPC组与对照组）无统计学差异。对照组的泽西奶牛在产后第1至10天血浆中非酯化脂肪酸和β-羟基丁酸的浓度低于其他品种和处理组合。与对照组奶牛相比，饲喂RPC的奶牛产前血清甘油三酯含量往往更高（17.0毫克/分升对14.7毫克/分升），分娩时血浆磷脂含量更低（65.2毫克/分升对78.1毫克/分升）。处理在其他时间点对胆固醇和磷脂无影响，但浓度呈现产前和产后干物质采食量的变化模式。在研究开始时奶牛体况评分为中等（平均值 = 3.3），至产后3周时体况并未过度下降（平均体况评分损失 = 0.5）；因此，奶牛可能不存在肝脏脂质蓄积的高风险。此外，产后计算得出的蛋氨酸平衡为负值；补充RPC可能未节省足够的蛋氨酸以产生生理效益。需要开展更多研究以确定胆碱如何影响脂肪肝综合征的预防或缓解，并确认荷斯坦奶牛和泽西奶牛之间的潜在差异。
