Harmuth-Hoene A E, Müller H
Z Ernahrungswiss. 1984 Mar;23(1):31-40. doi: 10.1007/BF02020894.
The metabolic fecal nitrogen was determined in 8 young rats (90-100 g body weight) using a single oral dose of 75 mg 15N-glycine. Four rats were fed a diet containing 8% guar and 4 rats received a control diet without guar. Compared to the control group, apparent protein digestibility and nitrogen balance were significantly lower in the guar group. After an initial steep rise the 15N-elimination in feces and urine (days 2-8 after 15N-glycine application) followed an exponential curve in at least 2 phases, with increasing half-time values. The proportion of metabolic fecal nitrogen to total fecal nitrogen was calculated from the 15N-atom-% excess, determined daily in urine and in feces. This calculation is based on the assumption that the specific 15N-activity (15N-atom-% excess) in urine represents the specific 15N-activity of the endogenous nitrogen pool. The addition of guar raised the proportion of metabolic fecal nitrogen from 51% (control) to 73%, corresponding to an increase in total fecal nitrogen loss (24 mg) observed in the guar-fed animals. This indicates that the rise in fecal nitrogen loss caused by guar is due almost entirely to enhanced secretion of endogenous nitrogen and not to undigested food protein. Based on the analysis of 2,6-diamino-pimelic acid in the feces of 4 rats the proportion of bacterial nitrogen in the feces was calculated. It amounted to 19.8% of total fecal N in the control group, and to 30.1% in the guar group, or to 39.4% and 44.4% of metabolic fecal nitrogen respectively. Obviously the increased dietary fiber intake also caused a rise in the amount of metabolic fecal nitrogen, which is derived from gastro-intestinal secretions and epithelial tissue.
给8只幼鼠（体重90 - 100克）单次口服75毫克15N - 甘氨酸来测定代谢粪氮。4只大鼠喂食含8%瓜尔豆胶的日粮，4只大鼠接受不含瓜尔豆胶的对照日粮。与对照组相比，瓜尔豆胶组的表观蛋白质消化率和氮平衡显著降低。在最初急剧上升之后，粪便和尿液中的15N消除量（15N - 甘氨酸施用后第2 - 8天）至少在两个阶段呈指数曲线，半衰期值增加。代谢粪氮占总粪氮的比例由每日测定的尿液和粪便中的15N原子过量百分比计算得出。该计算基于尿液中特定的15N活性（15N原子过量百分比）代表内源性氮库的特定15N活性这一假设。添加瓜尔豆胶使代谢粪氮的比例从51%（对照）提高到73%，这与喂食瓜尔豆胶的动物中观察到的总粪氮损失增加（24毫克）相对应。这表明瓜尔豆胶导致的粪氮损失增加几乎完全是由于内源性氮分泌增加，而非未消化的食物蛋白。基于对4只大鼠粪便中2,6 - 二氨基庚二酸的分析，计算出粪便中细菌氮的比例。对照组中细菌氮占总粪氮的19.8%，瓜尔豆胶组中占30.1%，分别占代谢粪氮的39.4%和44.4%。显然，膳食纤维摄入量的增加也导致了代谢粪氮量的增加，代谢粪氮源自胃肠道分泌物和上皮组织。
