Occurrence of intraportally‐infused urea‐¹⁵N in the urine of domestic fowl

Abstract

1. Measurements were made in situ to determine the occurrence of intraportally infused urea-15N in ureteral urine of the fowl. 2. Of the total amount of infused urea-15N, 15% was excreted intact into the urine (90% of urinary total 15N) whereas 9% remained unchanged in the blood (78% of blood non-protein-15N). 3. The proportions of non-protein-15N in the blood, liver and kidney were 12, 3 and 1%, respectively of the infused 15N. Protein-15N was 3% of that infused in blood and much less in liver and kidney. 4. About 1% of the infused 15N was observed in the urinary uric acid, and 3% of the infused 15N in non-protein N, other than urea, ammonia and glutamine amide N, of blood and liver. 5. No appreciable amounts of 15N were present in ammonia and glutamine amide N of blood, liver or kidney and in uric acid of liver or kidney. 6. The caecal contents contained about 1% of the infused 15N with 15% of this as ammonia-15N. 7. It is concluded that intraportal urea is mostly excreted unchanged into ureteral urine of the fowl.

Acute poisoning of silver gulls (Larus novaehollandiae) following urea fertilizer spillage

“…The concentrations of ammonia in the proventricular fluid (0.4 to 95 mmol/l) of affected birds was likely to be predominantly due to the environmental hydrolysis of urea, while the concentrations in the blood (1.2 to 36 mmol/l) would reflect a combination of environmental and in-vivo hydrolysis. Both urea and ammonia are rapidly absorbed intact from the avian gastrointestinal tract (Karasawa, 1984;Karasawa & Koji, 1994). The rapid uptake of ammonia expected with this gastrointestinal loading would exceed the maximal renal excretion rate of ammonia of 500 mmol/h per kg body weight (Long, 1982), and would result in rapid elevation of plasma levels.…”

Effect of colostomy on the occurrence of dietary [15N]urea in intestinal contents, blood, urine and tissues in chickens fed a low protein diet plus urea

“…The appearance of [ 15 N]urea, infused into the portal vein, in the urine of colostomised chickens and the disappearance of the excretory [ 15 N]urea in conventional birds demonstrated that the absorbed urea had flowed back from the cioaca into the colon and the caeca where it had been hydrolysed (Karasawa et al, 1992). The involvement of the caeca in the utilisation of dietary urea was also supported by the observation that urine was prevented from entering the caeca by colostomy and that such surgical modification had resulted in a considerable increase in urea excretion, almost accounting for all of the increase in total nitrogen excretion from colostomised birds (Karasawa, 1989;Karasawa and Maeda, 1994).…”