Nutrional and Physiological Study on Cecal Functions of Chickens

结果如下：（1）日粮尿素在胃肠道中不降解，在空肠中以完整的形式吸收。(2)吸收的尿素不水解，而是排泄到肾小管尿中。(3)尿中的尿素通过抗凝作用从泄殖腔带回盲肠，在那里被盲肠微生物水解成氨，并从盲肠壁吸收。(4)吸收的氨的一部分用于在肝脏中合成非必需氨基酸，一部分通过谷氨酰胺形成以尿酸的形式排出。(5)其他尿中含氮化合物也通过盲肠途径回收，并以与尿素相似的方式代谢。(6)通过这种氮循环系统通过盲肠回收的氮在蛋白质耗尽的鸡中被有效地利用，但在蛋白质充足的鸡中利用较少。(7)从肠道吸收逃逸的食虫体进入盲肠，对日粮氮的存留产生不利影响。(8)鸡体内氮的存留是基于粪便和尿液两种成分的平衡。(9)盲肠有益于在严重营养条件下野生鸟类的氮营养，但在营养良好的鸡。(10)盲肠结扎不影响日粮代谢能值。(11)盲肠菌群受粪便和尿液的进入、宿主周围环境和膳食纤维（如多酚和低聚糖）的调节。(12)结果表明，日粮中添加果胶可增加盲肠的重量和面积，盲肠在氮代谢中起重要作用，但在能量代谢中不起作用，日粮纤维通过盲肠发酵参与营养物质的利用。

The results are summarized as follows;(1) Dietary urea is not degraded at the gastro-intestinal tract, and absorbed in intact form from the jejunum. (2) The absorbed urea is not hydrolyzed but excreted into tubular urine. (3) The urinary urea is carried back from the cloaca into the ceca by antiperistalsis, hydrolyzed there to ammonia by cecal microflora and absorbed from the cecal wall. (4) A part of the absorbed ammonia is utilized for synthesis of non-essential amino acids in the liver and a part is excreted in the form of uric acid by way of glutamine formation. (5) Other urinary nitrogenous compounds are also recovered by the pathway through ceca and metabolized in a similar manner to urea. (6) The recovered nitrogen by this nitrogen recycling system through ceca is utilized effectively in the protein-depleted chicken but less utilized in the protein-adequate chickens. (7) The entry into the ceca of digesta escaped from intestinal absorption adversely exerts on dietary nitrogen retention.(8) Nitrogen retention in chickens is based on balance of two entries of digesta and urine. (9) Ceca beneficially function in nitrogen nutrition of wild birds under severe nutritional conditions but not in well-nourished chickens. (10) Cecal ligation does not affect metabolizable energy value of diets. (11) Cecal microflora is regulated by the entry of digesta and urine, ambient circumstances around hosts and dietary fiber such as polyphenol and oligosaccharide. (12) Dietary pectin increases cecal weight and area.It is concluded that the ceca of chickens play an important role in nitrogen metabolism according to protein supply, but not any role in energy metabolism, and that dietary fiber is involved in nutrient utilization through cecal fermentation.