Department of Animal Sciences, The Ohio State University, Wooster 44691, USA.
J Anim Sci. 2012 Dec;90(13):4951-61. doi: 10.2527/jas.2011-4736. Epub 2012 Jul 24.
Dried distillers grains with solubles (DDGS) can decrease rumen pH because of their inherent acidity. Two replicated 4 × 4 Latin square experiments were conducted with ruminally fistulated heifers to determine the effects of dietary inclusion and NaOH treatment of DDGS on rumen metabolism. In Exp. 1, dietary treatments were 0%, 20%, 40%, or 60% DDGS on a DM basis. The remainder of the diet was 15% corn silage, 20% vitamin-mineral supplement, and corn (to replace DDGS) on a DM basis. Dry matter intake decreased (linear; P < 0.01) with increasing dietary inclusion of DDGS. Rumen pH was less than 5.3 from 1.5 to 12 h after feeding regardless of dietary DDGS inclusion, and mean rumen pH tended to decrease (linear; P = 0.08) with increasing DDGS. Rumen fluid S(2-) and rumen H(2)S gas concentrations increased (P < 0.01) with increasing DDGS inclusion at all time points postfeeding. At 3 h after feeding, ruminal concentrations of acetate, propionate, and total VFA increased linearly (P < 0.04) with increasing dietary inclusion of DDGS. Acetate to propionate ratio (A:P) ranged from 0.97 to 1.25 and was not affected (P = 0.88) by diet over time. In Exp. 2, dietary treatments were 1) 25% DDGS inclusion, untreated, 2) 60% DDGS inclusion, untreated, 3) 25% DDGS inclusion, treated with 2% NaOH, and 4) 60% DDGS inclusion, treated with 2% NaOH. Dry matter intake decreased (P < 0.01) when 60% DDGS was included in the diet regardless of NaOH treatment. Mean rumen pH was greater (P < 0.01) when NaOH-treated DDGS was fed regardless of dietary inclusion level. There were interactions (P ≤ 0.06) of NaOH treatment by DDGS inclusion by time for mean H(2)S and S(2-) concentrations. These interactions occurred because the magnitude of the response to NaOH treatment was greater for the 60% DDGS diets than for the 25% DDGS diets only from 1.5 to 9 h postfeeding. There were no interactions (P > 0.05) of NaOH treatment by DDGS inclusion on VFA concentrations. Acetate concentration decreased (P = 0.04) in cattle fed 60% DDGS diets at 0 h, but at 3 h postfeeding it tended to increase (P = 0.06). Total lactate was less than 1.30 for all dietary treatments at all time points. Treating DDGS with 2% NaOH may increase rumen pH and decrease H(2)S, thereby alleviating polioencephalomalacia.
干燥的酒糟及其可溶性物（DDGS）由于其内在的酸性，可能会降低瘤胃 pH 值。通过对瘤胃有瘘管的奶牛进行了两次重复的 4×4 拉丁方实验，以确定日粮中添加和用氢氧化钠处理 DDGS 对瘤胃代谢的影响。在实验 1 中，日粮处理为 0%、20%、40%或 60%的 DDGS，以干物质为基础。其余的日粮为 15%玉米青贮、20%维生素-矿物质补充剂和玉米（代替 DDGS），以干物质为基础。随着日粮中 DDGS 含量的增加，干物质摄入量呈线性下降（P < 0.01）。无论日粮中 DDGS 的添加量如何，瘤胃 pH 值在喂食后 1.5 至 12 小时均低于 5.3，并且随着 DDGS 的增加，平均瘤胃 pH 值呈线性下降（P = 0.08）。随着日粮中 DDGS 含量的增加，瘤胃液中 S（2-）和瘤胃 H（2）S 气体浓度在所有时间点均呈线性增加（P < 0.01）。在喂食后 3 小时，瘤胃中乙酸、丙酸和总挥发性脂肪酸的浓度呈线性增加（P < 0.04），随着日粮中 DDGS 含量的增加。乙酸与丙酸的比例（A：P）在 0.97 到 1.25 之间，并且不受饮食的影响（P = 0.88）。在实验 2 中，日粮处理为 1）25% DDGS 含量，未处理，2）60% DDGS 含量，未处理，3）25% DDGS 含量，用 2%氢氧化钠处理，4）60% DDGS 含量，用 2%氢氧化钠处理。无论氢氧化钠处理与否，当日粮中包含 60%的 DDGS 时，干物质摄入量都会减少（P < 0.01）。无论日粮中 DDGS 的添加量如何，用氢氧化钠处理的 DDGS 喂养时，平均瘤胃 pH 值更高（P < 0.01）。氢氧化钠处理与 DDGS 含量之间存在时间交互作用（P ≤ 0.06），影响平均 H（2）S 和 S（2-）浓度。这种相互作用的发生是因为只有在 1.5 至 9 小时后，60% DDGS 日粮的氢氧化钠处理反应程度大于 25% DDGS 日粮。氢氧化钠处理与 DDGS 含量对挥发性脂肪酸浓度没有相互作用（P > 0.05）。在 0 小时，喂食 60% DDGS 日粮的奶牛的乙酸浓度降低（P = 0.04），但在 3 小时后，乙酸浓度趋于增加（P = 0.06）。所有日粮处理在所有时间点的总乳酸含量均低于 1.30。用 2%氢氧化钠处理 DDGS 可能会增加瘤胃 pH 值并减少 H（2）S，从而缓解麻痹性肌红蛋白尿症。
