Girard Christiane L, Berthiaume Robert, Stabler Sally P, Allen Robert H
a Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada , Sherbrooke , QC , Canada.
b Division of Hematology , University of Colorado Denver and Health Sciences , Aurora , Colorado , USA.
Arch Anim Nutr. 2009;63(5):379-88. doi: 10.1080/17450390903020364.
Cobalamin analogues in samples of rumen fluid, duodenal and ileal digesta and faeces of lactating dairy cows collected during the course of two nutritional studies were identified using a recently developed liquid chromatography-mass spectrometry method in order to determine if changes in diet composition could alter their proportions. Only cobalamin and cobinamine were detected in feedstuffs; six supplementary analogues were detected in the gastrointestinal tract content. The proportion of analogues produced by the gastrointestinal microflora was higher than the vitamin itself. The mode of conservation of forage had no effect on the proportion of analogues in rumen fluid, duodenal digesta and faeces, whereas increasing metabolisable protein supply raised the proportion of analogues reaching the duodenum (p = 0.008). The proportion of analogues was higher in ileal than duodenal digesta, this observation probably indicates a preferential absorption of cobalamin in the small intestine. The present results showed that changes in diet composition could alter cobalamin synthesis in rumen.
在两项营养研究过程中收集的泌乳奶牛瘤胃液、十二指肠和回肠消化物及粪便样本中的钴胺素类似物，采用最近开发的液相色谱 - 质谱法进行鉴定，以确定日粮组成的变化是否会改变它们的比例。在饲料中仅检测到钴胺素和钴胺胺；在胃肠道内容物中检测到六种补充类似物。胃肠道微生物群产生的类似物比例高于维生素本身。饲料的保存方式对瘤胃液、十二指肠消化物和粪便中类似物的比例没有影响，而可代谢蛋白质供应的增加提高了到达十二指肠的类似物比例（p = 0.008）。回肠消化物中类似物的比例高于十二指肠消化物，这一观察结果可能表明小肠中钴胺素的优先吸收。目前的结果表明，日粮组成的变化可能会改变瘤胃中钴胺素的合成。
