Regulation of nitrogen salvage in non-ruminants

猪和其他非反刍动物能够通过尿素循环过程和随后在胃肠道中产生的微生物氨基酸来回收氮。然而，尿素再循环进入肠道的调节机制以及影响尿素再循环和随后氮利用程度的因素（如饮食、生理）尚不清楚。在反刍动物中，除了非特异性的细胞旁运动外，尿素进入瘤胃的运输部分是由于促进性尿素转运蛋白（UT-B和水通道蛋白）。膳食因素，如纤维和蛋白质的摄入，可能通过改变肠道环境和改变动物和常驻微生物的营养供应来影响氮的回收。

Pigs and other non-ruminant animals are capable of salvaging nitrogen through the process of urea recycling and subsequent microbial amino acid production in the gastrointestinal tract. However, the regulatory mechanisms for urea recycling into the gut and the factors (e.g., dietary, physiological) influencing the extent of urea recycling and subsequent nitrogen utilization are not well understood. In the ruminant, it has been shown that urea transport into the rumen is due, in part, to facilitative urea transporters (UT-B and aquaporins) in addition to non-specific paracellular movement. Dietary factors, such as fibre and protein intake, may influence nitrogen salvage through altering the gut environment and changes in nutrient supply to the animal and resident microbes.