Krawielitzki K, Zebrowska T, Schadereit R, Kowalczyk J, Hennig U, Wünsche J, Herrmann U
Department of Animal Nutrition Oskar Kellner, Academy of Agricultural Sciences, GDR, Research Centre of Animal Production, Dummerstorf-Rostock.
Arch Tierernahr. 1990 Jan-Feb;40(1-2):25-37. doi: 10.1080/17450399009428378.
In an experiment with 3 pigs (initial live weight 30 kg, each fitted with 2 re-entrant fistulas in duodenum and ileum, one labelled with 15N), the duodenal and ileum digesta was exchanged. The N and 15N contents were estimated in faeces, urine, duodenal and ileum digesta of all experimental animals as well as in special organs and in the contents of different tract sections. The 15N excess (15N') of N compounds secreted into the gut lumen was determined using the 15N' in pancreas, gut mucosa and TCA-soluble blood serum. From measuring the digesta passage through the 3 sections of the digestive tract: 1. mouth ... duodenum, 2. duodenum ... ileum, 3. ileum ... after (Krawielitzki et al., 1989) the absorption and secretion rates of nitrogen were calculated. Secretion into the 1st section amounted to 5.3 g N/d (= 15% of intake) and the absorption to approximately 1% of intake. In the 2nd section the corresponding dates were 8.9 resp. 38.6 g N/d (= 25 resp. 110% of N intake), and in the 3rd one 1.9 resp. 8.4 g N/d (= 5.6 resp. 24% of N intake). Total absorption amounted to 134% of N intake and the over all re-absorption of endogenous N compounds secreted into the gut lumen to about 90%. During the passage the amount of endogenous N (g/d) decreased from 5.3 at the duodenum to 3.8 at the ileum to 1.6 in the faeces, but the relative portion increased (13 resp. 35 resp. 39%). An incorporation into body proteins occurred only from N compounds absorbed in the 1st and in the 2nd section. N (or 15N) absorbed in the large intestine was almost quantitatively excreted by urine. The method of digesta exchange between cannulated labelled and unlabelled pigs seems to be a suitable method to estimate absorption and secretion of exogenous and endogenous N portions in various sections of the digestive tract.
在一项对3头猪（初始活重30千克，每头猪在十二指肠和回肠各安装2个再进入式瘘管，其中一个用15N标记）进行的实验中，交换了十二指肠和回肠的消化物。对所有实验动物的粪便、尿液、十二指肠和回肠消化物以及特殊器官和不同肠道段内容物中的氮和15N含量进行了估算。利用胰腺、肠黏膜和三氯乙酸可溶性血清中的15N过量（15N'）来测定分泌到肠腔中的氮化合物的15N过量（15N'）。通过测量消化物在消化道3个部分的通过情况：1. 口腔……十二指肠，2. 十二指肠……回肠，3. 回肠……之后（Krawielitzki等人，1989年），计算出氮的吸收和分泌速率。在第一部分的分泌量为5.3克氮/天（=摄入量的15%），吸收量约为摄入量的1%。在第二部分，相应的数据分别为8.9和38.6克氮/天（=氮摄入量的25%和110%），在第三部分为1.9和8.4克氮/天（=氮摄入量的5.6%和24%）。总吸收量为氮摄入量的134%，分泌到肠腔中的内源性氮化合物的总体重吸收量约为90%。在通过过程中，内源性氮的量（克/天）从十二指肠的5.3降至回肠的3.8，再降至粪便中的1.6，但相对比例增加（分别为13%、35%和39%）。只有在第一部分和第二部分吸收的氮化合物才会掺入体蛋白中。在大肠中吸收的氮（或15N）几乎全部通过尿液排出。在插管标记猪和未标记猪之间交换消化物的方法似乎是一种估算消化道各部分中外源性和内源性氮部分的吸收和分泌的合适方法。
