In a recent number of this Journal,’ a new method for the estimat,ion of urea in urine was described. This method consists in the conversion of the urea into ammonium carbonate by means of the urease of the soy bean, and an estimation of the alkalinity before and after the conversion by means of standard acid and methyl orange. The procedure is not directly applicable to the est,imation of urea...

According to the usually accepted concept, the urea removed from the blood by the kidneys is excreted in two forms, chiefly as urea itself, but partly as ammonia. That the ammonia of the urine is formed in the kidneys was demonstrated by Nash and Benedict (1921), in work which has been confirmed by other authors (cf. Peters and Van Slyke, I, p. 373). Evidence from animal experiments in v4vo has...

The objective of this study was to examine the effects of 6 days of emersion on nitrogen metabolism and excretion in the Chinese soft-shelled turtle, Pelodiscus sinensis. Despite having a soft shell with a cutaneous surface that is known to be water permeable, P. sinensis lost only ~2% of body mass and was able to maintain its hematocrit and plasma osmolality, [Na(+)] and [Cl(-)] during 6 days ...

Soybean is traditionally grown in soil, where root symbiosis with Bradyrhizobium japonicum can supply nitrogen (N), by means of bacterial fixation of atmospheric N2. Nitrogen fertilizers inhibit N-fixing bacteria. However, urea is profitably used in soybean cultivation in soil, where urease enzymes of telluric microbes catalyze the hydrolysis to ammonium, which has a lighter inhibitory effect c...

One primiparous and 3 multiparous lactating Holstein cows fitted with ruminal and duodenal cannulas were used in a 4 x 4 Latin square design to determine the efficacy of adding urea to a corn silage-based diet on ruminal fermentation and microbial protein synthesis. Dietary treatments were 0, 0.3, 0.6, and 0.9% urea in diet dry matter (DM); urea was manually top dressed and incorporated into th...

Fifty-eight crossbred yearling heifers (BW = 383 ± 25 kg) were utilized in a completely randomized 2 x 2 factorial arrangement of treatments designed to evaluate the effects of finishing diets containing dried distiller's grains supplemented with degradable intake protein on feedlot performance and carcass characteristics. Dietary treatments contained 10 or 20% dried distiller's grains (DDG) re...

Gulf toadfish (Opsanus beta) use a unique pulsatile urea excretion mechanism that allows urea to be voided in large pulses via the periodic insertion or activation of a branchial urea transporter. The precise cellular and subcellular location of the facilitated diffusion mechanism(s) remains unclear. An in vitro basolateral membrane vesicle (BLMV) preparation was used to test the hypothesis tha...

Effects of increased ammonia and/or arginine absorption across the portal-drained viscera (PDV) on net splanchnic (PDV and liver) metabolism of nitrogenous compounds and urinary N excretion were investigated in six catheterized Hereford x Angus steers (501 +/- 1 kg BW) fed a 75% alfalfa:25% (as-fed basis) corn-soybean meal diet (0.523 MJ of ME/[kg BW(0.75).d]) every 2 h without (27.0 g of N/kg ...

The environmental benefits of producing biofuels from sugarcane have been questioned due to greenhouse gas emissions during the biomass production stage, especially nitrous oxide (NO) associated with nitrogen (N) fertilization. The objective of this work was to evaluate the use of nitrification inhibitors (NIs) dicyandiamide (DCD) and 3,4 dimethylpyrazole phosphate (DMPP) and a controlled-relea...

SCHMIDT-NIELSEN, BODIL, AND CAROLYN RUTH SHRAUGER. Hundling of urea and related cumpuunds by the renal tubuks of the frog. Am. J. Physiol. PO&$: 483-488. 1963.-A high arginase activity is found in the kidney of the adult frog Ram catesbeiana which actively secretes urea. Urea accumulates in the kidney in concentrations around seven to eight times the blood concentration. To test whether the kid...