The urinary excretion of purine derivatives method is an effective approach for estimating microprotein output in the rumen. which is non-invasive and easy to operate. The method can accurately estimate the changes of microprotein output in the rumen. It has a lower residual variation and more consistent results. Two improvements are spot sampling method and dahlin method. The advantage of spot sampling method is the determination on appropriate sampling time, by which a high relevance between PD/C ( the ratio of purine derivative to creatinine) and the daily quantity of purine derivatives can be obtained; In dahlin method. inulin. a more reliable urinary marker, is used for estimating daily creatinine excretion. [ Chinese Journal of Animal Nutrition ,2011 ,23 ( 1 ) : 10-14 ]%尿嘌呤衍生物法具有非侵入性和操作方便等优点,是估测微生物蛋白质产量的一种有效方法.该方法能够准确估测瘤胃微生物蛋白质产量的变化,且其残差变异低于其他方法,估测结果的一致性较好.对其改良后的方法有点采样法和菊糖法.点采样法优点在于可以确定恰当的采样时间,保证尿嘌呤衍生物与肌酐的比例(PD/C)与尿嘌呤衍生物日排出量的高相关性;菊糖法是利用了菊糖这种可靠尿液标记物来测定肌酐日排出量.
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