scholarly journals The effects of dietary sucrose and the concentrations of plasma urea and rumen ammonia on the degradation of urea in the gastrointestinal tract of cattle

1980 ◽  
Vol 43 (1) ◽  
pp. 125-140 ◽  
Author(s):  
P. M. Kennedy
Keyword(s):  
Gastrointestinal Tract ◽  
Medicago Sativa ◽  
Multiple Regression ◽  
Ammonia Concentration ◽  
Urea Concentration ◽  
Entry Rate ◽  
Plasma Urea ◽  
Plasma Urea Concentration ◽  
The Relationship ◽  
Microbial N

1. The rates of entry of urea into plasma, of urea degradation in the gastrointestinal tract, and the partition of that degradation between the rumen and post-ruminal tract were determined by use of [14C]urea and NaH14CO3 in Hereford steers receiving hay diets with or without sucrose. The concentrations of plasma urea and rumen ammonia were varied by infusions of urea into the rumen or abomasum.2. For all diets, plasma urea concentration was related to urea entry rate, to degradation of urea in the whole gastrointestinal tract, and to its degradation in the post-ruminal tract, but the relationship with its degradation in the rumen was poor.3. Degradation of urea in the rumen was related in a multiple regression in a curvilinear manner in three groups of diets (pasture-hay alone, pasture-hay–lucerne (Medicago sativa) mixtures, diets with sucrose), and negatively to rumen ammonia concentration for pasture-hay diets, and diets with sucrose.4. Ruminal clearance of urea (rate of urea degradation per plasma urea concentration) was negatively related to the rumen ammonia concentration for steers given diets with sucrose, of pasture-hay with or without urea infusions. Provision of sucrose in the diet significantly increased clearance.5. Enhanced urea degradation in the rumen associated with dietary sucrose supplements accounted for 0.4 of additional microbial N synthesis in the rumen.6. The partition of transfer of urea to the rumen via saliva and through the rumen wall is discussed.

An analysis of the relationship between plasma urea and ammonia concentration in dairy cattle fed a consistent diet over a 100-day period

2007 ◽  
Vol 74 (4) ◽  
pp. 412-416 ◽  
Author(s):  
Richard A Laven ◽  
D Claire Wathes ◽  
Kevin E Lawrence ◽  
Rex J Scaramuzzi
Keyword(s):  
Good Predictor ◽  
Control Diet ◽  
Ammonia Concentration ◽  
Urea Concentration ◽  
Plasma Urea ◽  
Plasma Ammonia ◽  
Dietary Nitrogen ◽  
Plasma Urea Concentration ◽  
The Relationship ◽  
Elevate Plasma

Measurement of plasma urea concentration is often used to identify a risk of dietary nitrogen-associated infertility. However, the use of plasma urea concentration in this way relies on it being an effective predictor for other potential toxic products associated with nitrogen metabolism (such as plasma or uterine ammonia). Recent research has shown that dietary nitrogen-associated infertility can be produced by diets which elevate plasma ammonia concentration without markedly increasing plasma urea concentration. Thus for cattle on different diets plasma urea concentration cannot be used to predict plasma ammonia concentration. This study evaluated whether plasma urea concentration could be used to predict plasma ammonia concentration in cattle kept on consistent diets. Data were analysed from a study where 42 cattle had been fed a control diet or the control diet plus 250 g urea per cow per day and had had weekly measurements of post-prandial plasma urea and ammonia concentrations. This analysis found that over a 100-d period, plasma urea concentration was relatively constant and unaffected by time while plasma ammonia concentration was significantly more variable, being affected by time since the study started, and whether cows began the study in the first or second group. Correlation between plasma ammonia and urea was limited; plasma urea concentration explained only 3·8% of the variation in plasma ammonia concentration. These data suggest that, even in cows on consistent diets, plasma urea concentration is not a good predictor of plasma ammonia, and that a simple urea threshold may not accurately identify the risk of dietary nitrogen-associated infertility.

scholarly journals Determination of nitrogen requirement for microbial growth from the effect of urea supplementation of a low N diet on abomasal N flow and N recycling in wethers and lambs

1976 ◽  
Vol 36 (3) ◽  
pp. 353-368 ◽  
Author(s):  
Sarah A. Allen ◽  
E. L. Miller
Keyword(s):  
Crude Protein ◽  
The Body ◽  
Urea Concentration ◽  
Metabolizable Energy ◽  
Entry Rate ◽  
Simple Diffusion ◽  
Plasma Urea ◽  
Urea Excretion ◽  
Plasma Urea Concentration ◽  
Microbial N

1. Plasma urea entry rate, urinary urea excretion and, by difference, urea recycling in the body, together with the flow of non-ammonia N through the abomasum and digestion of dry matter (dm) before the abomasum were determined in both wethers and lambs receiving cereal-starch diets supplemented with urea to give 60–120 g crude protein (N × 6.25)/kgdm.2. Lambs excreted less urea in urine than wethers given the same diet.3. Relationships between plasma urea entry rate or urine urea excretion rate and plasma urea concentration were different for lambs compared to wethers suggesting greater conser vation of body N by renal control in lambs.4. Recycling of urea was not related to plasma urea concentration in wethers but was related exponentially in lambs, suggesting recycling is controlled rather than the result of simple diffusion from the blood to the gastro-intestinal tract.5. Abomasal non-ammonia-N flow was similar for wethers and lambs and increased linearly with urea supplementation.6.dmdigestion prior to the abomasum was not significantly altered, although there was a tendency for decreased digestion of the basal diet given to lambs.7. Maximum microbial N flow to the abomasum was estimated as 30 g N/kg organic matter (OM) fermented in the rumen.8. This work and the literature reviewed suggested maximum net microbial production can be obtained when the diet supplies an amount of fermentable N equal to the microbial N output. It is calculated the diet should supply approximately 26 g fermentable N/kg digestible OM or 1.8 g fermentable N/MJ metabolizable energy. This corresponds to a fermentable crude protein supply varying from 65 to 130 g/kg DM as digestible OM content increases from 400 to 800 g/kg DM.

scholarly journals Metabolism of urea in sheep

1967 ◽  
Vol 21 (2) ◽  
pp. 353-371 ◽  
Author(s):  
M. R. Cocimano ◽  
R. A. Leng
Keyword(s):  
Flow Rate ◽  
Crude Protein ◽  
Excretion Rate ◽  
Urine Flow ◽  
The Body ◽  
Urea Concentration ◽  
Urine Flow Rate ◽  
Entry Rate ◽  
Plasma Urea ◽  
Plasma Urea Concentration

1. The entry rates of urea into the urea pool of the body fluids have been measured in sheep given rations varying in crude protein percentage from 3.5 to 27.3.2. Results obtained with a single injection and with continuous infusions of [14C]urea were essentially the same.3. The difference between the entry rate and the rate of excretion of urea in the urine was taken to indicate the quantity of urea degraded in the alimentary tract.4. Plasma concentrations and urea entry rates were significantly and linearly related.5. The relationship between excretion rate and plasma urea concentration was best described by a cubic equation.6. Degradation of urea in sheep was found to be extensive in all the animals studied; as the protein intake increased, the quantity of urea degraded also increased but the percentage of urea entering the body pool that was degraded was decreased. Animals given a ration containing 3.5% crude protein degraded 76–92% of the urea entering the body pool.7. A rectilinear relationship was found between pool size and plasma urea concentration. The urea space in animals given low-protein rations was significantly less than in animals on high-protein rations.8. The effects of starvation for 2, 4 and 6 days on urea metabolism in sheep were investi-gated. In a11 the sheep starved for 2 days there was a significant increase in urea pool size, but the entry rate was markedly depressed indicating a retention of urea in the body pool on starvation.9. A significant amount of nitrogen was found to go through the system: rumen ammonia → portal blood ammonia→blood urea→rumen ammonia.10.Urea excretion rate, urea clearance by the kidney, urine flow rate and the ratio of the concentration of urea in urine to that in plasma (urea U:P ratio) were also examined.11. There were significant correlations between urine flow rate and urea excretion and between plasma urea concentration and urine flow rate.

scholarly journals Influences of dietary sucrose and urea on transfer of endogenous urea to the rumen of sheep and numbers of epithelial bacteria

1981 ◽  
Vol 46 (3) ◽  
pp. 533-541 ◽  
Author(s):  
P. M. Kennedy ◽  
R. T. J. Clarke ◽  
L. P. Milligan
Keyword(s):  
Sodium Bicarbonate ◽  
Ammonia Concentration ◽  
Bromus Inermis ◽  
Urea Clearance ◽  
Plasma Urea ◽  
The Third ◽  
Rumen Epithelium ◽  
Plasma Urea Concentration ◽  
Brome Grass ◽  
The Relationship

1. The rates of transfer of plasma urea to the rumen of six sheep given brome grass (Bromus inermis) pellets alone or with supplements of sucrose or urea were determined using [14C]urea and14C-labelled sodium bicarbonate infusions during three periods.2. The sheep were slaughtered after the third period and samples of rumen epithelium were taken for assessment of numbers of adherent bacteria.3. Maximum transfer (0·31 g nitrogen/h) of urea to the rumen was observed for sheep given supplements of 150 g sucrose/d plus 20 g urea/d. Maximum clearance of plasma urea to the rumen (rate of urea transfer to the rumen per unit plasma urea concentration, 5·8 1/h) was observed for sheep given 300 g sucrose/d.4. Urea clearance to the rumen was negatively related to rumen ammonia concentration; the slope of the relationship was increased with each addition of sucrose to the diet.5. Numbers of facultative bacteria adherent to the rumen epithelium were increased by urea and sucrose supplements.6. The results are discussed in relation to a hypothesis which relates the ureolytic capability of the bacteria adherent to the rumen epithelium to the control of the rate of transfer of urea into the rumen.

UREA DEGRADATION IN THE CAMEL

1976 ◽  
Vol 56 (3) ◽  
pp. 595-601 ◽  
Author(s):  
B. EMMANUEL ◽  
B. R. HOWARD ◽  
M. EMADY
Keyword(s):  
Crude Protein ◽  
Urea Concentration ◽  
Pool Size ◽  
Entry Rate ◽  
Plasma Urea ◽  
Dietary Nitrogen ◽  
Urea Metabolism ◽  
Plasma Urea Concentration ◽  
Kinetics Of ◽  
General Plasma

Following a single injection of 14C-urea, the kinetics of urea metabolism have been studied in two female Arabian camels (Camelus dromedarius) fed roughage diets containing 6.1 (diet A), 9.6 (diet B), and 13.6% (diet C) crude protein. In general, plasma urea concentration, urea pool size, urea entry rate and urinary urea excretion rate increased as the dietary nitrogen intake increased. The mean extents of urea degradation were approximately 86, 74 and 47% for diets A, B, and C, respectively, as calculated from the ratio of urea degradation rate to urea entry rate, or from the fraction of 14C-urea recovered in the urine. The following parameters were linearly related: urea entry rate and urea pool size, urea pool size and plasma urea concentration, percentage urea degraded and urea entry rate, and percentage urea degraded and crude protein intake.

TRACER STUDIES OF UREA RECYCLING EN SHEEP

1970 ◽  
Vol 50 (1) ◽  
pp. 129-135 ◽  
Author(s):  
A. L. FORD ◽  
L. P. MILLIGAN
Keyword(s):  
Steady State ◽  
Plasma Concentration ◽  
Intravenous Infusion ◽  
Urea Concentration ◽  
Tracer Studies ◽  
Plasma Urea ◽  
Plasma Urea Concentration ◽  
The Relationship ◽  
Urea Recycling ◽  
General Prediction

The urea transferred from the plasma to the digestive tract of fed sheep was measured employing 14C-urea as a tracer, after establishing metabolic steady state. Plasma urea concentrations were adjusted by intravenous infusion of unlabelled urea. Recycled urea, within the physiological range of plasma urea concentrations, fitted a linear function of plasma concentration. Recycling, in this study, of urea in different animals and for different rations, followed the relationship: [Formula: see text], SE = 2.27, r = 0.85, where [Formula: see text] urea recycled per day and X = plasma urea concentration (up to 45 mg/100 ml).A regression equation, incorporating data from other studies, that could be used for the general prediction of urea recycling in sheep from the plasma urea concentration, was presented. The ration did not appear to influence significantly urea recycling aside from its effects on the plasma urea concentration.

Genome-wide association for plasma urea concentration in sheep

2021 ◽  
Vol 248 ◽  
pp. 104483
Author(s):  
Taiana Cortez de Souza ◽  
Tatiana Cortez de Souza ◽  
Gregorí Alberto Rovadoscki ◽  
Luiz Lehmann Coutinho ◽  
Gerson Barreto Mourão ◽  
...  
Keyword(s):  
Urea Concentration ◽  
Genome Wide Association ◽  
Plasma Urea ◽  
Genome Wide ◽  
Plasma Urea Concentration

Urea Excretion in the Camel

1957 ◽  
Vol 188 (3) ◽  
pp. 477-484 ◽  
Author(s):  
Bodil Schmidt-Nielsen ◽  
Knut Schmidt-Nielsen ◽  
T. R. Houpt ◽  
S. A. Jarnum
Keyword(s):  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Urea Concentration ◽  
Nitrogen Excretion ◽  
Renal Tubules ◽  
Urea Clearance ◽  
Plasma Urea ◽  
Urea Excretion ◽  
Plasma Urea Concentration

The nitrogen excretion was studied in the one-humped camel, Camelus dromedarius. When a growing camel was maintained on a low N intake (dates and hay) the amount of N excreted in the form of urea, NH3 and creatinine decreased to 2–3 gm/day. This decrease was caused by a drop in urea excretion from 13 gm to 0.2–0.5 gm/day. Urea given intravenously during low N intake was not excreted but was retained. (The camel like other ruminants can utilize urea for microbial synthesis of protein.) The renal mechanism for urea excretion was investigated by measuring urea clearance and glomerular filtration rate during a period of 7 months. During normal N intake about 40% of the urea filtered in the glomeruli were excreted in the urine while during low N intake only 1–2% were excreted. The variations in urea clearance were independent of the plasma urea concentration and of glomerular filtration rate, but were related to N intake and rate of growth. No evidence of active tubular reabsorption of urea was found since the urine urea concentration at all times remained higher than the simultaneous plasma urea concentration. The findings are not in agreement with the current concept for the mechanism of urea excretion in mammals. It is concluded that the renal tubules must either vary their permeability to urea in a highly selective manner or secrete urea actively.

Effects of intraruminal infusions of urea, sucrose or urea plus sucrose on plasma urea and glucose kinetics in sheep fed chopped lucerne hay

1993 ◽  
Vol 121 (1) ◽  
pp. 125-130 ◽  
Author(s):  
Y. Obara ◽  
D. W. Dellow
Keyword(s):  
Plasma Glucose ◽  
Rumen Fluid ◽  
Glucose Production ◽  
Ammonia Concentration ◽  
Irreversible Loss ◽  
Glucose Kinetics ◽  
Plasma Urea ◽  
Urea Excretion ◽  
Urea Kinetics ◽  
Plasma Urea Concentration

SUMMARYThe effect of rumen fermentation on the relationship between urea and glucose kinetics was examined in sheep fed chopped lucerne hay with intraruminal infusions of water, urea, sucrose, or urea plus sucrose at Palmerston North, New Zealand in 1986. Sheep were fed hourly and infused intraruminally with water (1200 m1/day), or a similar volume containing either urea alone (13·7g/day), sucrose alone (178·2 g/day) or urea (14·6 g/day) plus sucrose (175·0 g/day). The added sucrose resulted in a lower rumen ammonia concentration (P< 0·05), lower plasma urea concentration (P< 0·05) and reduced urinary urea excretion (P< 0·05). Urea recycled to the gut tended to increase with the sucrose, urea or sucrose plus urea treatments compared with the water treatment. The fermentation of sucrose in the rumen resulted in decreases in ruminal pH (P< 0·05) and in the ratio of acetate to propionate (A:P) (P< 0·05). The infusion of sucrose also increased the concentration of propionate in rumen fluid (P< 0·05), tended to increase the plasma glucose level and increased plasma glucose irreversible loss (P< 0·05). The infusion of urea resulted in an increase in the plasma urea level (P< 0·05), urea pool size (P< 0·05) and urea irreversible loss (P< 0·01). However, urea infusion did not affect glucose metabolism or volatile fatty acid (VFA) fermentation. The effects of sucrose infusion on glucose and urea kinetics were broadly similar when given alone or with urea, apart from changes in the urea degradation rate. It was concluded that the additional fermentative activity resulting from sucrose increased propionate production which, in turn, was available for glucose production, thus ‘sparing’ amino acids for tissue protein utilization and reducing urea excretion.

Residual kidney function and plasma urea concentration in patients with chronic renal failure

1990 ◽  
Vol 22 (6) ◽  
pp. 573-579 ◽  
Author(s):  
O. Schück ◽  
J. Erben ◽  
H. Nádvorníková ◽  
V. Teplan ◽  
O. Marečková ◽  
...  
Keyword(s):  
Renal Failure ◽  
Chronic Renal Failure ◽  
Kidney Function ◽  
Urea Concentration ◽  
Plasma Urea ◽  
Residual Kidney Function ◽  
Plasma Urea Concentration
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