The aim of the study was to examine the effects of an elevated dietary cobalt supply to dairy cows on rumen fermentation parameters and microbial vitamin B12 synthesis in the rumen. Five lactating dairy cows fitted with a ruminal and a duodenal cannula were subsequently fed either a ration containing only the native cobalt content (0.17 mg Co/kg DM) or a ration supplemented with cobalt sulphate (0.29 mg Co/kg DM). The pH-value, the ammonia concentration as well as the concentration and the molar proportions of short chain fatty acids in the rumen were not significantly influenced by feeding the ration with the higher cobalt content. While there was no difference in microbial protein flow, the cobalamin flow at the duodenum was significantly elevated in supplemented animals (3.67 ± 0.69 vs. 8.63 ± 2.22 mg B12/d). The efficiency of cobalt utilisation for ruminal vitamin B12 synthesis was calculated to be 7.1 ± 1.3% for the unsupplemented and 9.5 ± 2.4% for the supplemented ration. Further investigation has to prove if there are any benefits for cows resulting from the elevated cobalamin synthesis measured, caused by feeding higher amounts of dietary cobalt.

中文翻译：

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增加钴供应对奶牛瘤胃中瘤胃参数和微生物维生素 B12 合成的影响

该研究的目的是检查奶牛日粮钴供应量增加对瘤胃发酵参数和瘤胃中微生物维生素 B12 合成的影响。随后，五头装有瘤胃和十二指肠插管的泌乳奶牛被喂食仅含有天然钴含量的日粮（0.17 毫克 Co/kg DM）或补充有硫酸钴（0.29 mg Co/kg DM）的日粮。饲喂钴含量较高的日粮对瘤胃中的pH值、氨浓度以及短链脂肪酸的浓度和摩尔比例没有显着影响。虽然微生物蛋白流量没有差异，但补充动物十二指肠的钴胺素流量显着升高（3.67 ± 0.69 与 8.63 ± 2.22 mg B12/d）。经计算，瘤胃维生素 B12 合成的钴利用效率对于未补充饲料为 7.1 ± 1.3%，对于补充饲料为 9.5 ± 2.4%。进一步的调查必须证明，如果饲喂较高量的日粮钴，所测得的钴胺素合成升高是否对奶牛有任何好处。