Estimating purine derivatives and nitrogen compound excretion using total urine collection or spot urine samples in grazing heifers
Estimating purine derivatives and nitrogen compound excretion using total urine collection or spot urine samples in grazing heifers
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DOI：
10.1111/jpn.13525
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发表时间：
2021-03-11
影响因子：
2.7
通讯作者：
Renno, Luciana Navajas
中科院分区：
文献类型：
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作者：
da Silva Junior, Jarbas Miguel;Pacheco Rodrigues, Joao Paulo;Renno, Luciana Navajas
本试验旨在通过全尿采集和现场取样的方法，评价饲粮中添加嘌呤衍生物（pd）和氮化合物（nc）的排泄量及其与肌酐的比值。5头Nelore小母牛（400 +/- 15公斤）采用5 × 5拉丁方形设计。各处理分别为精料（粗蛋白质220 g/kg干物质）添加量（0、3、6、9和12 g/kg BW）。在每个时间段，连续采集3天总尿（采样间隔为4 h、00:00-04:00、04:00-08:00、08:00-12:00、12:00-16:00、16:00-20:00和20:00-24:00）。每个时间段进行24小时（0、4、8、12、16和20小时）的尿样取样。测定肌酐、尿总氮（UN）、尿素氮（UreaN）、尿囊素和尿酸。肌酐排泄量为23.01 +/- 0.19 mg/kg BW，不受采集日、处理及其相互作用的影响（p < 0.05）。治疗影响PD排泄（p < 0.05），但不影响PD：肌酐比值（p < 0.05）。处理和采集时间对NC排泄有影响（p < 0.05），而UN：肌酐和尿素：肌酐比值无影响（p < 0.05）。肌酐排泄量和尿中PD：肌酐比值通过总采样和现场采样估算无显著差异（p < 0.05）。抽样方法对UN：肌酐比值和尿素：肌酐比值有显著影响（p < 0.05）。肌酸酐可以充分估计放牧母牛的尿排泄，并且可以使用一天中任何时间的单点尿液样本来估计放牧母牛的PD排泄。但要准确估计放牧小母牛尿液中NC的排泄量，需要两个尿样。
The study aimed to evaluate the excretion of purine derivatives (PDs) and nitrogen compounds (NCs) and their ratios with creatinine in supplemented Zebu heifers kept on pastures by comparing total urine collection and spot sampling. Five Nelore heifers (400 +/- 15 kg) were used in a 5 x 5 Latin square design. The treatments were the amount of concentrate (220 g of crude protein/kg dry matter) offered (0, 3, 6, 9 and 12 g/kg BW). In each period, the total urine collection was performed continuously for 3 days (subsampled at intervals of 4 h, 00:00-04:00 h, 04:00-08:00 h, 08:00-12:00 h, 12:00-16:00 h, 16:00-20:00 h and 20:00-24:00 h). The spot urine samplings were performed (in each period) for 24 h (0, 4, 8, 12, 16 and 20 h). Creatinine, total urinary nitrogen (UN), urea nitrogen (UreaN), allantoin and uric acid were analysed. Creatinine excretion was 23.01 +/- 0.19 mg/kg BW and was not affected by collection day, treatment or their interactions (p > 0.05). Treatments affected (p < 0.05) PD excretions, however did not affect the ratio PD:creatinine (p > 0.05). Treatments and collection time affected (p < 0.05) NC excretion, whereas the UN:creatinine and UreaN:creatinine ratios were not affected (p > 0.05). Creatinine excretion and the PD:creatinine ratios in the urine samples estimated by the total or spot sampling were not different (p > 0.05). However, sampling method affected (p < 0.05) the UN:creatinine and UreaN:creatinine (p < 0.05) ratios. Creatinine can adequately estimate urinary excretion in grazing heifers, and a single spot urine sample at any time of the day can be used to estimate PD excretion in grazing heifers. But two spot urine samples are needed for proper NC excretion estimations in grazing heifers' urine.