^(15)N尿素在兔体内消化吸收及利用机理研究 Ⅱ.切除盲肠兔对尿素氮的消化与利用影响

Studies on the Mechanism of Absorption, Digestion and Utilization of 15 N urea in Rabbits Ⅱ. Effect of Caecectomia on Urea N Digestion and Utlization in Rabbits

应用稳定同位素１５Ｎ尿素示踪技术，对试验兔经切除盲肠后进行消化代谢试验，研究其对尿素氮的消化与利用的影响。试验证明：切除盲肠抑制了兔对尿素的利用，并降低了氮平衡值；但随着兔肠道生长机能的恢复和食软粪习性的再现，弥补了部分负效应，使实际利用比率下降减缓。从胃肠中存留标记氮的形态分配剖析，总体表现为切除盲肠兔较正常兔的蛋白１５Ｎ比率下降、铵态１５Ｎ比率上升，且在大肠内容物中尤为突出。说明兔在去除巨大的盲肠微生物区系功能时，其氮素转化、合成菌体蛋白受阻。

Experiment of metabolism on caecum resected rabbits were carried out to study their digestion and utilization of urea N by using 15 N tracing technique. Three New Zealand white caecum resected rabbits(2 5 kg,male,3 months old) were fed with 15 N labelled urea in which N content was 45 74%. The gross energy of basal diet which included 13 31% crude protein was 1 34×10 7 J/kg.120 g basal diet was fed to every tested rabbits with addictive 1 2 g urea every day. Experimental results indicated that caecectomia inhibited the utilization of urea and decreased nitrogen balance value which would be improved as the restore of intestinal function and ingestion in soft feces. Compared with normal rabbits, the proportion of protein nitrogen and NH 4 + 15 N decreased and increased in caecum resected rabbits, respectively, which appeared obviously in large intestine. It could be elucidated that when rabbits caecum were resected, nitrogen transformation and synthesis were inhibited. As a result, nitrogen utilization declined.