Department of Diagnostic Medicine and Pathobiology, Kansas State University, Manhattan, KS 66506, USA.
J Anim Sci. 2013 Mar;91(3):1362-70. doi: 10.2527/jas.2012-5618. Epub 2013 Jan 24.
Distillers grains (DG), a co-product of ethanol production used as protein and energy supplements in cattle diets, have been shown to increase fecal shedding of Escherichia coli O157:H7, a major foodborne pathogen. The reason for the positive association is not known. Because DG often replaces grain in the diet, decreased starch content and flow to the hindgut may create a favorable environment for E. coli O157:H7. Our objective was to determine whether the addition of starch to a corn DG-supplemented diet negates the effects of DG on fecal shedding of E. coli O157:H7. We conducted a study with 21 steers fed 1 of 3 diets: a corn grain-based basal diet (CON), basal diet supplemented with 25% corn dried DG (DDG), and basal diet supplemented with 25% DDG with corn starch (DDG+S) added at a level intended to increase starch concentration to that of the CON diet. Steers, housed individually in a biosafety level 2 animal facility, were randomly allocated to treatment diets and orally inoculated with a 5-strain mixture (10(9) cfu per steer) of nalidixic acid-resistant (Nal(R)) E. coli O157:H7. Fecal samples were collected for 5 wk, and on d 35, steers were euthanized and necropsied to collect gut content samples. Fecal or gut samples were cultured to determine prevalence and concentrations of Nal(R) E. coli O157:H7. Dietary starch concentrations, based on feed analysis, were 46.3% in the CON compared with 43.3 and 41.3% in the DDG and DDG+S diets, respectively. Steers fed DDG or DDG+S diets shed Nal(R) E. coli O157:H7 more often (P = 0.0027 and 0.0003, respectively) and at greater concentrations (1.9 or 2.0 cfu/g; P = 0.0025 and 0.0006) than those fed CON diet (1.4 cfu/g), but no difference was observed between DDG and DDG+S diets. Cumulative prevalence and concentrations of Nal(R) E. coli O157:H7 were greater in gut samples collected at necropsy in steers fed DDG and DDG+S diets compared with those fed CON diet, but no difference was observed between DDG and DDG+S diets. The lack of effect of starch addition to the DDG diet on fecal shedding of E. coli O157:H7 may be because either the decreased starch content in the DG-supplemented diet is not a factor in the increased shedding of E. coli O157:H7 or inclusion of pure starch in the diet may not have achieved our intended goal to have starch flow into the hindgut similar to that of corn grain. The study confirms our previous finding of the positive association between feeding DG and fecal shedding of E. coli O157:H7.
酒糟（DG）是乙醇生产的副产品，用作牛饲料中的蛋白质和能量补充物，已被证明会增加大肠杆菌 O157:H7 的粪便排泄，大肠杆菌 O157:H7 是一种主要的食源性病原体。其阳性关联的原因尚不清楚。由于 DG 通常替代饲料中的谷物，淀粉含量和流向后肠的减少可能为大肠杆菌 O157:H7 创造了有利的环境。我们的目的是确定在玉米 DG 补充饮食中添加淀粉是否可以消除 DG 对大肠杆菌 O157:H7 粪便排泄的影响。我们对 21 头饲养的牛进行了一项研究，这些牛分别食用以下 3 种饮食中的 1 种：以玉米谷物为基础的基础饮食（CON），补充了 25%玉米干 DG（DDG）的基础饮食，以及补充了 25%DDG 并添加了玉米淀粉的基础饮食（DDG+S），目的是将淀粉浓度提高到 CON 饮食的水平。牛被单独安置在生物安全 2 级动物设施中，随机分配到处理饮食中，并通过口服接种含有 5 种耐药性（Nal（R））大肠杆菌 O157:H7 的混合菌株（每头牛 10（9）cfu）。收集粪便样本 5 周，并在第 35 天，对牛进行安乐死并进行尸检以收集肠道内容物样本。对粪便或肠道样本进行培养，以确定耐萘啶酸的大肠杆菌 O157:H7 的流行率和浓度。根据饲料分析，CON 中的饮食淀粉浓度为 46.3%，而 DDG 和 DDG+S 饮食中的淀粉浓度分别为 43.3%和 41.3%。饲喂 DDG 或 DDG+S 饮食的牛更频繁地（P = 0.0027 和 0.0003）和浓度更高地（1.9 或 2.0 cfu/g；P = 0.0025 和 0.0006）排泄 Nal（R）大肠杆菌 O157:H7，比饲喂 CON 饮食的牛（1.4 cfu/g），但 DDG 和 DDG+S 饮食之间没有差异。在尸检时收集的肠道样本中，饲喂 DDG 和 DDG+S 饮食的牛的 Nal（R）大肠杆菌 O157:H7 的累积流行率和浓度高于饲喂 CON 饮食的牛，但 DDG 和 DDG+S 饮食之间没有差异。在 DDG 饮食中添加淀粉对大肠杆菌 O157:H7 的粪便排泄没有影响，这可能是因为 DG 补充饮食中淀粉含量的减少不是大肠杆菌 O157:H7 排泄增加的因素，或者在饮食中添加纯淀粉可能无法实现我们将淀粉流入后肠的目的，使其类似于玉米谷物。该研究证实了我们之前关于 DG 喂养与大肠杆菌 O157:H7 粪便排泄之间存在正相关关系的发现。
