Cows are adapted to degrade structural plant carbohydrates (SC), such as cellulose and hemicelluloses, prevailing in grasses. Yet, the need for energy-dense diets in many intensive dairy production systems has shifted the dairy cattleʼs diet from SC-rich to high levels of starch. Feeding of starch-rich diets increases the risk of ruminal acidosis in cows, and feeding starch in the form of grains intensifies the competition over cereal grains and arable land among different livestock species, as well as between livestock and humans. Besides cellulose and hemicelluloses, grasses are also often rich in water-soluble carbohydrates (WSC), which comprise mono-, di-, oligo- and polysaccharides (fructans). Although the ruminal fermentation profile of mono- and disaccharides resembles that of starch, the degradation of oligo- and polysaccharides is slower, and their fermentation elicits a rather protecting effect on ruminal pH. When harvested in an early phase (i.e. ear emergence), grass hay and silages can reach WSC levels up to 150–200 g kg⁻¹ dry matter and energy levels close to starch-rich diets, allowing a significantly reduced inclusion of concentrate supplements. By doing so, this will enhance both rumen health and the sustainability of milk production. However, because the WSC are chemically very heterogeneous, the patterns and extent of their ruminal fermentation are difficult to predict without a clear analytical characterization. This review article aims to summarize both the benefits and potentials, as well as the challenges, with respect to using WSC-rich feedstuffs in the nutrition of dairy cattle and their effects on ruminal fermentation characteristics and milk production. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

中文翻译：

---

使用富含水溶性碳水化合物的饲料提高瘤胃健康和奶牛生产可持续性的潜力综述

奶牛适合降解草类中普遍存在的结构性植物碳水化合物 (SC)，例如纤维素和半纤维素。然而，许多集约化奶牛生产系统对高能量饮食的需求已经将奶牛的饮食从富含 SC 转变为高水平的淀粉。饲喂富含淀粉的日粮会增加奶牛瘤胃酸中毒的风险，而饲喂谷物形式的淀粉会加剧不同牲畜物种之间以及牲畜与人类之间对谷物和耕地的竞争。除了纤维素和半纤维素，禾本科还富含水溶性碳水化合物 (WSC)，其中包括单糖、二糖、寡糖和多糖（果聚糖）。尽管单糖和双糖的瘤胃发酵曲线与淀粉相似，但寡糖和多糖的降解较慢，并且它们的发酵对瘤胃的 pH 值具有相当的保护作用。在早期收获（即出穗）时，干草和青贮饲料的 WSC 水平可高达 150–200 g kg^-1干物质和能量水平接近富含淀粉的饮食，允许显着减少浓缩补充剂的加入。通过这样做，这将提高瘤胃健康和牛奶生产的可持续性。然而，由于 WSC 在化学上非常异质，如果没有明确的分析表征，则很难预测其瘤胃发酵的模式和程度。这篇综述文章旨在总结在奶牛营养中使用富含 WSC 的饲料及其对瘤胃发酵特性和产奶量的影响的好处和潜力以及挑战。© 2021 作者。John Wiley & Sons Ltd 代表化学工业协会出版的《食品和农业科学杂志》。