Diet effects on urine composition of cattle and N2O emissions
Diet effects on urine composition of cattle and N2O emissions
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DOI：
10.1017/s1751731113000578
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发表时间：
2013-06-01
期刊：
影响因子：
3.6
通讯作者：
Bannink, A.
中科院分区：
文献类型：
--
作者：
Dijkstra, J.;Oenema, O.;Bannink, A.
反刍动物生产有助于向环境排放氮(N)，主要是向空气排放氨（NH3）、氧化亚氮（N2O）和二氮（N-2），向地下水排放硝酸盐（NO3(-)），向地表水排放颗粒氮。膳食氮摄入量的变化尤其会影响尿氮的排泄，尿氮比粪氮更容易损失。我们的目标是回顾饮食对牛尿液中氮排泄水平和形式的影响，以及它对N2O排放的影响。尿中氮的排泄量变化很大。随着饲粮氮摄入量的减少或瘤胃微生物和宿主动物自身能量供应的增加，尿氮排泄量，特别是尿素氮的排泄量会减少。尿中的大部分氮（从50%到90%以上）以尿素的形式存在。其他含氮成分包括嘌呤衍生物（PD）、马尿酸、肌酸和肌酐。PD的排泄量与瘤胃微生物蛋白合成有关，而马尿酸的排泄量与饲粮中可降解酚酸浓度有关。牛尿氮浓度为3 ~ 20 g/l。高膳食矿物质水平会增加尿量，导致尿氮浓度降低，血浆和牛奶中的尿素浓度也会降低。在泌乳奶牛中，尿量的变化影响了乳尿素与尿氮排泄的关系，这阻碍了乳尿素作为尿氮排泄的准确指标的使用。土壤和水体中无处不在的微生物在牧场或畜舍中沉积后，将尿N组分转化为铵（NH4(+)），然后转化为NO3(-)，最终转化为N-2，同时释放N2O。尿中马尿酸、肌酸和肌酐的分解比尿素慢。马尿酸可能是N2O排放的天然抑制剂，但抑制条件尚未明确。尿液沉积或施用粪肥的地点的环境和土壤条件强烈影响N2O的释放。减少牛养殖N2O排放的主要饮食策略包括降低饲粮氮含量或增加能量含量，以及增加饲粮矿物质含量以增加尿量。为了进一步减少N2O的排放，需要采取综合的动物营养和排泄物管理方法。
Ruminant production contributes to emissions of nitrogen (N) to the environment, principally ammonia (NH3), nitrous oxide (N2O) and di-nitrogen (N-2) to air, nitrate (NO3 (-)) to groundwater and particulate N to surface waters. Variation in dietary N intake will particularly affect excretion of urinary N, which is much more vulnerable to losses than is faecal N. Our objective is to review dietary effects on the level and form of N excreted in cattle urine, as well as its consequences for emissions of N2O. The quantity of N excreted in urine varies widely. Urinary N excretion, in particular that of urea N, is decreased upon reduction of dietary N intake or an increase in the supply of energy to the rumen microorganisms and to the host animal itself. Most of the N in urine (from 50% to well over 90%) is present in the form of urea. Other nitrogenous components include purine derivatives (PD), hippuric acid, creatine and creatinine. Excretion of PD is related to rumen microbial protein synthesis, and that of hippuric acid to dietary concentration of degradable phenolic acids. The N concentration of cattle urine ranges from 3 to 20 g/l. High-dietary mineral levels increase urine volume and lead to reduced urinary N concentration as well as reduced urea concentration in plasma and milk. In lactating dairy cattle, variation in urine volume affects the relationship between milk urea and urinary N excretion, which hampers the use of milk urea as an accurate indicator of urinary N excretion. Following its deposition in pastures or in animal houses, ubiquitous microorganisms in soil and waters transform urinary N components into ammonium (NH4 (+)), and thereafter into NO3 (-) and ultimately in N-2 accompanied with the release of N2O. Urinary hippuric acid, creatine and creatinine decompose more slowly than urea. Hippuric acid may act as a natural inhibitor of N2O emissions, but inhibition conditions have not been defined properly yet. Environmental and soil conditions at the site of urine deposition or manure application strongly influence N2O release. Major dietary strategies to mitigating N2O emission from cattle operations include reducing dietary N content or increasing energy content, and increasing dietary mineral content to increase urine volume. For further reduction of N2O emission, an integrated animal nutrition and excreta management approach is required.