Humer Elke, Bruggeman Geert, Zebeli Qendrim
Institute of Animal Nutrition and Functional Plant Compounds, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine Vienna, 1210 Vienna, Austria.
Nutrition Sciences, Booiebos 5, 9031 Drongen (Gent), Belgium.
Animals (Basel). 2019 Aug 16;9(8):566. doi: 10.3390/ani9080566.
After parturition, cows undergo negative energy balance leading to fat mobilization, predisposing them to fatty liver syndrome and ketosis with major consequences for health and reproduction. Supplementation of rumen-protected choline (RPC) has attracted major research efforts during the last decade, assuming that choline improves liver function by increasing very low-density lipoprotein exportation from the liver, thereby improving metabolic profiles, milk production, and reproduction. However, the effects of RPC on production, health, and reproduction have been inconsistent. Therefore, the aim of this meta-analysis was to evaluate the effects of RPC supplementation, starting from d 20 (± 12.2) ante partum to d 53 (± 31.0) postpartum, on feed intake, milk production performance and metabolic profiles of dairy cows early postpartum. Data analyses from 27 published studies showed an increase in postpartal dry matter intake (from on average 19.1 to 19.9 kg/d; < 0.01) and milk yield (from on average 31.8 to 32.9 kg/d; = 0.03) in cows receiving RPC. Milk fat yield and milk protein yield were also increased ( ≤ 0.05), without changing milk protein and fat contents. However, no interactive effects between cow's milk yield level and RPC-supplementation as well as no dose-dependent effects of RPC supplementation were observed. Supplementing the diet with RPC showed no effects on blood metabolites (non-esterified fatty acids, beta-hydroxybutyrate, glucose, and cholesterol), independent of the milk yield level of the cows. An effect on liver triacylglycerol contents, incidence of ketosis, and mastitis could not be confirmed across all studies included in this meta-analysis. Also, the positive effects of RPC supplementation on reproductive performance were not consistent findings. In conclusion, supplementing RPC in lactating dairy cows showed positive effects on dry matter intake which likely caused the improved milk yield. However, RPC supplementation did not improve the metabolic health status of the cows. As several factors might be related to the responses to RPC, further research is needed to explore the precise mechanisms of RPC action in lactating cows, especially with regards to feed intake improvement and its related metabolic health-promoting potential in early lactating dairy cows.
分娩后，奶牛会经历负能量平衡，导致脂肪动员，使其易患脂肪肝综合征和酮病，对健康和繁殖产生重大影响。在过去十年中，瘤胃保护性胆碱（RPC）的补充引起了主要的研究关注，假设胆碱通过增加肝脏极低密度脂蛋白的输出量来改善肝功能，从而改善代谢状况、产奶量和繁殖性能。然而，RPC对生产、健康和繁殖的影响并不一致。因此，本荟萃分析的目的是评估从产前第20天（±12.2天）至产后第53天（±31.0天）补充RPC对产后早期奶牛采食量、产奶性能和代谢状况的影响。对27项已发表研究的数据分析表明，接受RPC的奶牛产后干物质采食量增加（从平均19.1千克/天增至19.9千克/天；P<0.01），产奶量增加（从平均31.8千克/天增至32.9千克/天；P = 0.03）。乳脂肪产量和乳蛋白产量也有所增加（P≤0.05），但乳蛋白和乳脂肪含量未发生变化。然而，未观察到奶牛产奶量水平与RPC补充之间的交互作用，也未观察到RPC补充的剂量依赖性效应。在奶牛的日粮中补充RPC对血液代谢物（非酯化脂肪酸、β-羟基丁酸、葡萄糖和胆固醇）没有影响，与奶牛的产奶量水平无关。在本荟萃分析纳入的所有研究中，均未证实对肝脏三酰甘油含量、酮病发病率和乳腺炎有影响。此外，RPC补充对繁殖性能的积极影响也并非一致的研究结果。总之，在泌乳奶牛中补充RPC对干物质采食量有积极影响，这可能导致产奶量提高。然而，补充RPC并未改善奶牛的代谢健康状况。由于有几个因素可能与对RPC的反应有关，则需要进一步研究以探索RPC在泌乳奶牛中的作用精确机制，特别是关于采食量改善及其在早期泌乳奶牛中促进代谢健康的潜在作用。
