Effect of levels of feed intake on plasma concentration and urinary excretion of purine derivatives in crossbred bulls

摘要: The study evaluated the potential of plasma concentration purine derivatives (PD) as an alternative to total urine collection method predict microbial nitrogen (MN) supply in crossbred bulls. In a completely randomized design, 15 growing bulls were divided into three groups and assigned levels (100, 80 60%) voluntary dry matter intake (VDMI) on diet wheat straw concentrate mixture (50:50). A metabolism trial ten days duration was conducted after 90 experimental feeding. daily urinary excretion allantoin PD decreased significantly (P<0.01) with reduction feed while creatinine remained similar animals fed at different levels. MN calculated from excreted (40.16 68.08 g/d) higher increased intake. reflected differences among 100 80% VDMI, it could not same 60% VDMI. Daily glomerular filtration rate (GFR) found be there fall GFR, when lowered results this revealed that, if is used index protein supply, variation GFR needs considered. Therefore, measurement better indicator than concentration.