Shaani Yoav, Shpirer Jen, Alon Tamir, Livshits Lilya, Mabjeesh Sameer, Moallem Uzi
Department of Ruminant Science, Institute of Animal Sciences, The Volcani Institute, Rishon LeZion 7505101, Israel; Department of Animal Science, the Robert H. Smith Faculty of Agriculture, Food, and Environment, the Hebrew University of Jerusalem, Rehovot 7610001, Israel; Department of Cattle Husbandry, Extension Service, Ministry of Agriculture, Bet-Dagan 50250, Israel.
Department of Ruminant Science, Institute of Animal Sciences, The Volcani Institute, Rishon LeZion 7505101, Israel; Department of Animal Science, the Robert H. Smith Faculty of Agriculture, Food, and Environment, the Hebrew University of Jerusalem, Rehovot 7610001, Israel.
J Dairy Sci. 2025 Sep 3. doi: 10.3168/jds.2025-26961.
Several factors influence the effectiveness of forage in ruminant rations, including NDF content and the physical nature, fragility, digestibility, and more of the forage. Recently, several studies suggested using the undigestible NDF (uNDF) fraction as a possible approach to achieve a more precise ration. The objective of the current study was to reduce the forage content of the diet by using the in vitro forage uNDF for diet formulation and to determine the effects on production, rumen environment, and digestibility. Thirty-four cows were divided into 2 groups in a crossover design study. Treatments consisted of either (1) a control (CTL) diet containing 35.8% forage (DM basis), 11.8% forage uNDF estimated through 30 h of in vitro fermentation (uNDF), and 10% forage uNDF estimated through 48 h of in vitro fermentation (uNDF) based on 20% wheat silage and 15.8% wheat hay, or (2) a low-forage (LF) diet containing 30.6% forage, 11.8% forage uNDF, and 10.4% forage uNDF based on 20% wheat silage, 2.2% wheat hay, and 8.3% wheat straw. Each period lasted 35 d, and data collection occurred during the final 21 d. Milk yields were recorded daily, and milk samples were taken weekly. Two rumen samples were collected twice for VFA, pH, and ammonia, and 8 fecal samples were collected for total-tract digestibility measurements. No differences were observed in rumen pH, ammonia, and VFA concentrations. Apparent total-tract digestibility of DM, OM, protein, ether extracts, and NDF was higher in the CTL diet. Milk yields (52.2 and 51.7 kg/d, respectively), 4% FCM, and ECM yields were higher in the CTL than in the LF treatment. The milk fat and protein content did not differ, the milk fat tended to be higher, and the milk protein yield was higher in the CTL treatment. The DMI was 3.2% higher in the CTL than in the LF treatment (32.7 vs. 31.7 kg/d, respectively), and the milk-to-DMI ratio was higher in the LF than in the CTL treatment. In summary, reducing the forage content by balancing the diet for forage uNDF reduced the DMI, milk, fat, and protein yields and digestibility, probably due to the high inclusion rate of wheat straw in the LF diet. However, the production efficiency of milk was higher in the LF treatment. Further research is required to fine-tune the proportion of forage uNDF and to determine the optimal exchange of forage feedstuffs in the diet.
有几个因素会影响反刍动物日粮中饲草的有效性，包括中性洗涤纤维（NDF）含量以及饲草的物理性质、脆性、消化率等。最近，多项研究表明，使用不可消化中性洗涤纤维（uNDF）部分作为一种可能的方法来实现更精确的日粮配制。本研究的目的是通过使用体外饲草uNDF进行日粮配方来降低日粮中的饲草含量，并确定其对生产性能、瘤胃环境和消化率的影响。在一项交叉设计研究中，将34头奶牛分为2组。处理包括：（1）对照（CTL）日粮，含有35.8%的饲草（干物质基础），通过30小时体外发酵估计的11.8%饲草uNDF（uNDF），以及基于20%小麦青贮和15.8%小麦干草通过48小时体外发酵估计的10%饲草uNDF；或（2）低饲草（LF）日粮，含有30.6%的饲草，11.8%的饲草uNDF，以及基于20%小麦青贮、2.2%小麦干草和8.3%小麦秸秆的10.4%饲草uNDF。每个时期持续35天，数据收集在最后21天进行。每天记录产奶量，每周采集牛奶样本。采集两次瘤胃样本用于测定挥发性脂肪酸（VFA）、pH值和氨，采集8次粪便样本用于测定全消化道消化率。瘤胃pH值、氨和VFA浓度未观察到差异。CTL日粮中干物质、有机物、蛋白质、乙醚提取物和NDF的表观全消化道消化率更高。CTL组的产奶量（分别为52.2和51.7千克/天）、4%乳脂校正乳（FCM）和能量校正乳（ECM）产量均高于LF组。牛奶脂肪和蛋白质含量无差异，CTL组牛奶脂肪含量有升高趋势，牛奶蛋白质产量更高。CTL组的干物质采食量（DMI）比LF组高3.2%（分别为32.7和31.7千克/天），LF组的奶料比高于CTL组。总之，通过平衡日粮中饲草uNDF来降低饲草含量会降低DMI、牛奶、脂肪和蛋白质产量以及消化率，这可能是由于LF日粮中小麦秸秆的高添加率所致。然而，LF组的牛奶生产效率更高。需要进一步研究来微调饲草uNDF的比例，并确定日粮中饲草原料的最佳替代比例。
