Wageningen UR Livestock Research, PO Box 65, 8200 AB Lelystad, the Netherlands.
J Dairy Sci. 2011 Aug;94(8):4016-27. doi: 10.3168/jds.2011-4233.
The effects of a dietary supplement of rumen-protected choline on feed intake, milk yield, milk composition, blood metabolites, and hepatic triacylglycerol were evaluated in periparturient dairy cows. Thirty-eight multiparous cows were blocked into 19 pairs and then randomly allocated to either one of 2 treatments. The treatments were supplementation either with or without (control) rumen-protected choline. Treatments were applied from 3 wk before until 6 wk after calving. Both groups received the same basal diet, being a mixed feed of grass silage, corn silage, straw, and soybean meal, and a concentrate mixture delivered through transponder-controlled feed dispensers. For all cows, the concentrate mixture was gradually increased from 0 kg/day (wk -3) to 0.9 kg of dry matter (DM)/d (day of calving) and up to 8.1 kg of DM/d on d 17 postcalving until the end of the experiment. Additionally, a mixture of 60 g of a rumen-protected choline supplement (providing 14.4 g of choline) and of 540 g of soybean meal or a (isoenergetic) mixture of 18 g of palm oil and 582 g of soybean meal (control) was offered individually in feed dispensers. Individual feed intake, milk yield, and body weight were recorded daily. Milk samples were analyzed weekly for fat, protein, and lactose content. Blood was sampled at wk -3, d 1, d 4, d 7, d 10, wk 2, wk 3, and wk 6 and analyzed for glucose, nonesterified fatty acids, and β-hydroxybutyric acid. Liver biopsies were taken from 8 randomly selected pairs of cows at wk -3, wk 1, wk 4, and wk 6 and analyzed for triacylglycerol concentration. We found that choline supplementation increased DM intake from 14.4 to 16.0 kg/d and, hence, net energy intake from 98.2 to 109.1 MJ/d at the intercept of the lactation curve at 1 day in milk (DIM), but the effect of choline on milk protein yield gradually decreased during the course of the study. Choline supplementation had no effect on milk yield, milk fat yield, or lactose yield. Milk protein yield was increased from 1.13 to 1.26 kg/d at the intercept of the lactation curve at 1 DIM, but the effect of choline on milk protein yield gradually decreased during the course of the study. Choline supplementation was associated with decreased milk fat concentration at the intercept of the lactation curve at 1 DIM, but the effect of choline on milk fat concentration gradually decreased as lactation progressed. Choline supplementation had no effect on energy-corrected milk yield, energy balance, body weight, body condition score, and measured blood parameters. Choline supplementation decreased the concentration of liver triacylglycerol during the first 4 wk after parturition. Results from this study suggest that hepatic fat export in periparturient dairy cows is improved by choline supplementation during the transition period and this may potentially decrease the risk for metabolic disorders in the periparturient dairy cow.
本研究旨在评估围产期奶牛日粮中添加包膜胆碱对采食量、产奶量、乳成分、血液代谢物和肝三酰甘油的影响。将 38 头经产奶牛按 19 对分组，然后随机分为 2 个处理组之一：添加（处理组）或不添加（对照组）包膜胆碱。处理从产前 3 周开始，持续至产后 6 周。两组均接受相同的基础日粮，即混合青贮草、玉米青贮、秸秆和豆粕，并通过应答器控制的饲料分配器提供浓缩饲料混合物。对于所有奶牛，浓缩饲料混合物逐渐从 0kg/d（产前 3 周）增加到 0.9kg/d 的干物质（产后第 1 天），并在产后第 17 天增加到 8.1kg/d，直到实验结束。此外，在饲料分配器中单独提供 60g 包膜胆碱补充剂（提供 14.4g 胆碱）和 540g 豆粕或 18g 棕榈油和 582g 豆粕（对照组）的混合物。每天记录个体采食量、产奶量和体重。每周分析一次牛奶样本以测定脂肪、蛋白质和乳糖含量。在产前 3 周、第 1 天、第 4 天、第 7 天、第 10 天、第 2 周、第 3 周和第 6 周采集血液样本来分析葡萄糖、非酯化脂肪酸和β-羟丁酸。在产前 3 周、第 1 周、第 4 周和第 6 周从 8 对随机选择的奶牛中采集肝活检样本，并分析三酰甘油浓度。我们发现，胆碱补充剂使奶牛在第 1 天的泌乳曲线截距处的干物质摄入量从 14.4kg/d 增加到 16.0kg/d，从而使净能摄入量从 98.2MJ/d 增加到 109.1MJ/d，但胆碱对乳蛋白产量的影响在研究过程中逐渐降低。胆碱补充剂对产奶量、乳脂产量或乳糖产量没有影响。乳蛋白产量从泌乳曲线截距处的 1.13kg/d 增加到 1.26kg/d，但随着研究的进行，胆碱对乳蛋白产量的影响逐渐降低。胆碱补充剂降低了泌乳曲线截距处的牛奶脂肪浓度，但随着泌乳的进行，胆碱对牛奶脂肪浓度的影响逐渐降低。胆碱补充剂对校正能量的产奶量、能量平衡、体重、体况评分和测量的血液参数没有影响。胆碱补充剂在产后前 4 周降低了肝脏三酰甘油的浓度。本研究结果表明，围产期奶牛在过渡期通过胆碱补充提高了肝脂肪输出，这可能降低围产期奶牛发生代谢紊乱的风险。
