饲粮NFC/NDF比例对奶牛瘤胃中微生物尿素氮代谢流的影响  

Effect of Dietary NFC/NDF Ratio on the Metabolic Flux of Microbial Urea Nitrogen in the Rumen of Dairy Cows

作　　者：张仕琦 郑楠[1] 王加启[1] 赵圣国[1] ZHANG Shiqi;ZHENG Nan;WANG Jiaqi;ZHAO Shengguo(Institute of Animal Science,Chinese Academy of Agricultural Sciences,Beijing 100193,China)

机构地区：[1]中国农业科学院北京畜牧兽医研究所,北京100193

出　　处：《畜牧兽医学报》2025年第3期1302-1312,共11页ACTA VETERINARIA ET ZOOTECHNICA SINICA

基　　金：中国农业科学院重大任务(CAAS-ZDRW202308);中国博士后科学基金资助项目(2023M743835)。

摘　　要：旨在探究改变饲粮NFC/NDF比例模拟不同能量供应速度,阐明能量供应对瘤胃微生物尿素氮利用效率和尿素氮代谢流向的调控作用,为尿素高效利用提供参考。通过体外发酵技术,将40个发酵瓶随机分为4组(n=10),为扣除15 N本底值,每组添加常规尿素(n=5)和15 N-尿素(n=5,15 N 15 N-尿素丰度:99.08 atom%),每组NFC/NDF比例分别为0.89、1.10、1.33和1.66。进行24 h体外发酵,并采集发酵液分析发酵参数、微生物15 N丰度以及15 N代谢流。结果表明,随着饲粮中NFC/NDF比例的增加,微生物蛋白质产量和尿素氮利用率呈线性增加(P<0.05)。代谢组分析表明,饲粮中NFC/NDF比例改变了瘤胃微生物的嘌呤代谢、氨循环、谷氨酸代谢等代谢途径。15 N标记代谢流分析表明,尿素氮流向34种含氮化合物,涉及氨基酸、核苷酸和能量代谢。随着饲粮NFC/NDF比例上升,尿素氮更多流向脱氧胸苷酸、UDP-葡萄糖和氨基酸等代谢物,从而活化了氨基酸和核苷酸代谢途径。在本试验的体外条件下,饲粮快速发酵碳水化合物比例的增加能促进尿素氮向微生物氨基酸和核苷酸转化,进而提高尿素氮利用率和微生物蛋白产量。This paper aimed to investigate different energy supply rates simulated by varying the dietary NFC/NDF ratio to elucidate the role of energy supply in regulating urea nitrogen utilization efficiency and urea nitrogen metabolism fluxes of rumen microorganisms,and to provide a reference for the efficient urea utilization.In this study,by in vitro fermentation technique,forty fermentation flasks were randomly divided into 4 groups(n=10),and in order to deduct the 15 N abundance background value,conventional urea(n=5)and 15 N-urea(n=5,15 N 15 N-urea abundance:99.08 atom%)were added to each group,and the NFC/NDF ratios of each group were 0.89,1.10,1.33,and 1.66,respectively.A 24 h in vitro fermentation was carried out and the fermentation broth was collected for the analysis of fermentation parameters,microbial 15 N abundance and 15 N metabolic flux.The results showed that microbial protein production and urea nitrogen utilization increased linearly(P<0.05)with increasing dietary NFC/NDF ratio.Metabolomic analysis showed that dietary NFC/NDF ratios altered metabolic pathways such as the purine metabolism,ammonia cycle,and glutamate metabolism of rumen microorganisms.15 N metabolic flux analysis of labelled metabolic fluxes showed that urea nitrogen fluxed to 34 nitrogen-containing compounds involved in amino acid,nucleotide,and energy metabolism.As the dietary NFC/NDF ratio increased,urea nitrogen flowed more to metabolites such as deoxy thymidylate,UDP-glucose and amino acids,which activated amino acid and nucleotide metabolic pathways.Under the in vitro conditions of this experiment,an increase in the proportion of dietary fast-fermenting carbohydrates promotes the conversion of urea nitrogen to microbial amino acids and nucleotides,improving urea nitrogen utilization and microbial protein production.

关 键 词：奶牛 瘤胃微生物 尿素氮 同位素标记 

分 类 号：S823.911.5[农业科学—畜牧学]