USDA-Agricultural Research Service, Pasture Systems and Watershed Management Research Unit, University Park, PA 16802-3702.
USDA-Agricultural Research Service, Pasture Systems and Watershed Management Research Unit, University Park, PA 16802-3702.
J Dairy Sci. 2020 Aug;103(8):7028-7038. doi: 10.3168/jds.2019-17627. Epub 2020 May 29.
A continuous-culture fermentor study was conducted to assess nutrient digestibilities, volatile fatty acid (VFA) concentrations, microbial protein synthesis, bacterial nitrogen (N) efficiency, and enteric methane (CH) production of four 50:50 grass-legume diets, randomly assigned in a 4 × 4 Latin square design. Four legumes with different concentrations of condensed tannins (CT) were tested: alfalfa [ALF; Medicago sativa L., non-CT legume]; birdsfoot trefoil [BFT; Lotus corniculatus L., low-CT legume]; crown vetch [CV; Securigera varia (L.) Lassen, moderate-CT legume]; and sericea lespedeza [SL; Lespedeza cuneata (Dum. Cours.) G. Don, high-CT legume]. Orchardgrass (Dactylis glomerata L.) was the common forage used in all diets. Four fermentors were evaluated over four 10-d periods by feeding 82 g of dry matter (DM)/d in 4 equal feedings. Methane output was recorded every 10 min. Effluent samples were collected during the last 3 d of the experiment, composited by fermentor and period, and analyzed for pH and VFA, as well as DM, organic matter, crude protein, neutral detergent fiber, and acid detergent fiber for determination of apparent and true nutrient digestibilities. Microbial protein synthesis and bacterial efficiency were estimated by analysis of N flows and purines. The CT concentrations were 3, 21, 38 and 76 g/kg of DM for ALF, BFT, CV, and SL diets, respectively. The SL diet had decreased fiber digestibilities and total VFA concentrations compared with the other diets. This resulted in the least total CH production in the SL diet. Bacterial N efficiency per kilogram of organic matter truly digested was lower in the SL diet than in the BFT and CV diets. The lowest CH production per unit of digestible nutrients was also found in the SL diet. Further work should be conducted to find optimal diets (by testing other legumes, rations, and sources of CT) for reducing CH emissions without negatively affecting ruminal digestion to maintain or improve productivity.
进行了一项连续培养发酵罐研究，以评估四种 50:50 草本-豆科植物日粮的养分消化率、挥发性脂肪酸 (VFA) 浓度、微生物蛋白合成、细菌氮 (N) 效率和肠道甲烷 (CH) 产量。采用 4×4 拉丁方设计，将日粮随机分配。测试了四种具有不同单宁 (CT) 浓度的豆科植物：紫花苜蓿[ALF; Medicago sativa L.，非 CT 豆科植物]；百脉根[BFT; Lotus corniculatus L.，低 CT 豆科植物]；大巢菜[CV; Securigera varia (L.) Lassen，中 CT 豆科植物]和胡枝子[SL; Lespedeza cuneata (Dum. Cours.) G. Don，高 CT 豆科植物]。所有日粮均使用果园草 (Dactylis glomerata L.) 作为共同饲草。在四个 10 天的试验期内，通过每天饲喂 82 g 干物质 (DM)，在四个等分饲料中评估四个发酵罐。每 10 min 记录一次甲烷排放量。在试验的最后 3 天收集流出物样品，按发酵罐和时间进行混合，并分析 pH 值和 VFA 以及 DM、有机质、粗蛋白、中性洗涤剂纤维和酸性洗涤剂纤维，以确定表观和真实养分消化率。通过分析氮流动和嘌呤来估计微生物蛋白合成和细菌效率。ALF、BFT、CV 和 SL 日粮的 CT 浓度分别为 3、21、38 和 76 g/kg DM。与其他日粮相比，SL 日粮的纤维消化率和总 VFA 浓度降低，导致 SL 日粮的总 CH 产量最低。与 BFT 和 CV 日粮相比，SL 日粮中每千克真正消化的有机物质的细菌 N 效率较低。在 SL 日粮中，每单位可消化养分的 CH 产量最低。应进一步开展工作，通过测试其他豆科植物、日粮和 CT 的来源，找到降低 CH 排放而不影响瘤胃消化以维持或提高生产力的最佳日粮。
