ABSTRACT The objective of this study was to investigate the relationship between plasma amino acid (AA) concentration and urinary nitrogen (N) concentration of dairy heifers offered cut plantain or perennial ryegrass-white clover pasture indoors. Twelve Jersey-Friesian heifers aged 9–10 months were equally assigned to two dietary treatments (plantain vs. perennial ryegrass-white clover pasture) in a completely randomised design. Urinary N concentration was lower in plantain fed heifers (1.4 g/kg) than in perennial ryegrass-white clover pasture fed heifers (3.4 g/kg). Feeding cut plantain or perennial ryegrass-white clover pasture did not have an effect on either plasma essential AA, non-essential AA or total AA. There was no association found between plasma AA concentration and urinary N concentration in the present study. Therefore, the urinary N concentration reduction in plantain fed heifers compared with perennial ryegrass-white clover pasture cannot be attributed by the differences in plasma AA.

中文翻译：

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喂食车前草或黑麦草的小母牛血浆氨基酸浓度和尿氮浓度之间没有关系

摘要 本研究的目的是研究在室内切下车前草或多年生黑麦草白三叶草牧场的奶牛血浆氨基酸 (AA) 浓度与尿氮 (N) 浓度之间的关系。在完全随机设计中，12 头 9-10 个月大的泽西-弗里西亚小母牛被平均分配到两种饮食处理（车前草与多年生黑麦草-白三叶草牧场）。大蕉喂养的小母牛（1.4 g/kg）的尿氮浓度低于多年生黑麦草-白三叶草喂养的小母牛（3.4 g/kg）。饲喂切好的车前草或多年生黑麦草-白三叶草牧场对血浆必需氨基酸、非必需氨基酸或总氨基酸没有影响。在本研究中没有发现血浆 AA 浓度和尿 N 浓度之间存在关联。所以，