Two experiments were conducted to determine: 1) the impact of strained rumen fluid (SRF) alone or SRF with particle-associated microorganisms (PAO) included and dilution on in vitro dry matter digestibility (DMD) and 2) the impact of trace mineral (TM) source on in vitro fermentation characteristics and TM solubility under simulated abomasal and intestinal conditions. In Experiment 1, three cannulated steers were adapted to a diet formulated to meet the nutrient requirements for lactating dairy cows. Strained RF was obtained by straining rumen content through 2 layers of cheesecloth. Half of the remaining digesta was washed with McDougall’s buffer and filtered through 2 layers of cheesecloth to obtain PAO. Both SRF and PAO were filtered again through 8 layers of cheesecloth. Strained RF was mixed with either McDougall’s buffer (SRF) or PAO (SRF+PAO) at a ratio of 1:2 or 1:4 and incubated at 39°C for 12 h using the ground basal diet as the substrate. Digestibility of DM was greater in digestion tubes containing SRF and SRF+PAO at a 1:2 ratio. In Experiment 2, eight steers fitted with ruminal cannula were blocked by body weight and assigned to one of two treatment groups. Treatments consisted of 10 mg Cu, 40 mg Mn, and 60 mg Zn/kg DM from either: 1) sulfate (STM) or 2) hydroxychloride (HTM) sources. Steers were housed in individual pens and fed the same diet as described in experiment 1. Dietary TM treatments were mixed with dried distillers grains and mixed in the diet, by hand, immediately after basal diet delivery. Dietary treatments were fed for 14 d. On day 15, SRF+PAO was collected from each steer (STM-RF and HTM-RF) and used in a series of in vitro crossover experiments. In vitro substrates (S) used were the ground diets consumed by the animals on each treatment (STM-S and HTM-S). Incubations containing HTM-S had greater (P < 0.01) total VFA concentration and propionic acid molar proportions, but lesser (P < 0.01) acetic acid molar proportions than STM-S. Rumen fluid from steers supplemented with HTM had a greater (P < 0.03) total VFA than STM-RF at 24h post incubation. After 12 h post incubation, the molar proportion of propionic acid in HTM-RF was lesser (P = 0.04) than STM-RF. After simulated abomasal digestion, soluble Mn concentration in HTM-S was greater (P < 0.01) than STM-S. These data indicate that the source of trace minerals can influence in vitro rumen fermentation characteristics and Mn solubility under simulated abomasal conditions.

中文翻译：

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微量矿物质来源影响体外发酵特性和微量矿物质溶解度


进行了两个实验来确定：1） 单独过滤瘤胃液 （SRF） 或包含颗粒相关微生物 （PAO） 和稀释的 SRF 对体外干物质消化率 （DMD） 的影响，以及 2） 微量矿物质 （TM） 来源对体外发酵特性的影响和模拟肠道条件下的 TM 溶解度。在实验 1 中，三头空心公牛适应了为满足泌乳奶牛营养需求而配制的日粮。通过通过 2 层粗棉布过滤瘤胃内容物来获得应变的 RF。剩余消化液的一半用 McDougall 缓冲液洗涤，并通过 2 层粗棉布过滤，得到 PAO。SRF 和 PAO 均通过 8 层粗棉布再次过滤。将应变的 RF 与 McDougall 缓冲液 （SRF） 或 PAO （SRF+PAO） 以 1：2 或 1：4 的比例混合，并在 39°C 下以研磨基础日粮为底物孵育 12 小时。DM 在含有 SRF 和 SRF+PAO 的消化管中以 1：2 的比例更高。在实验 2 中，8 头装有瘤胃套管的阉牛被体重阻断，并被分配到两个治疗组之一。处理包括 10 mg Cu、40 mg Mn 和 60 mg Zn/kg DM，来源为：1） 硫酸盐 （STM） 或 2） 羟基氯化物 （HTM）。将公牛饲养在单独的围栏中，并饲喂与实验 1 中描述的相同饮食。膳食 TM 处理与干酒糟混合，并在基础饮食交付后立即手工混合在饮食中。日粮处理饲喂 14 d。第 15 天，从每头公牛 （STM-RF 和 HTM-RF） 收集 SRF + PAO 并用于一系列体外交叉实验。 使用的体外底物 （S） 是动物在每次处理 （STM-S 和 HTM-S） 中食用的研磨饲料。含有 HTM-S 的孵育具有大于 （P < 0.01） 总 VFA 浓度和丙酸摩尔比例，但小于 （P < 0.01） 乙酸摩尔比例比 STM-S。在孵育后 24 小时，补充 HTM 的阉牛瘤胃液的总 VFA 大于 STM-RF （P < 0.03）。孵育后 12 小时后，HTM-RF 中丙酸的摩尔比例小于 STM-RF （P = 0.04）。模拟腹腔消化后，HTM-S 中的可溶性 Mn 浓度大于 STM-S （P < 0.01）。这些数据表明，微量矿物质的来源会影响体外瘤胃发酵特性和模拟 abomasal 条件下的 Mn 溶解度。