Percentage Of Urea Research Articles

Nitrogen metabolism of beef steers fed endophyte-free tall fescue hay: effects of ruminally protected methionine supplementation.

Level of nitrogen (N) intake and ruminally protected methionine supplementation were evaluated in eight Angus growing steers (initial BW 253+/-21 kg, final BW 296+/-21 kg) in a replicated 4+/-4 Latin square design. The steers were fed two endophyte-free tall fescue (Festuca arundinacea) hays that contained 2.2 (LO) or 2.8% (HI) of DM as N and were either supplemented or not with ruminally protected methionine (10 g metabolizable methionine/d). Diets were fed to provide adequate energy for 0.5 kg ADG and sufficient protein for maintenance (LO), or protein to support 0.5 kg ADG (HI). Following at least 14 d of adjustment, N balance was measured for 6 d. Isotopic urea was infused (15N15N-urea, 0.164 mmol urea N/h) via a jugular catheter for 56 h and urine was collected from 48 to 56 h to measure urea kinetics. Jugular blood was collected during the balance trial, and serum was analyzed for serum urea N (SUN). By design, daily N intake was greater (P < 0.05) for HI (112 g) than for LO (89 g). Compared with LO, steers when fed HI had greater (P < 0.05) daily DMI (4,217 vs 4,151 g), fecal N (34.4 vs 31.2 g), N digested (77.1 vs 57.7 g), urine N (48.3 vs 37.5 g), urine urea N excretion (34.6 vs 24.8 g), and N retained (29.8 vs 21.1 g). When fed HI steers also had higher (P < 0.05) urine urea N concentration (276 vs 219 mM), SUN (8.7 vs 6.7 mM), N digestibility (69.1 vs 64.9%), percentage of urinary N present as urea (71.5 vs 66.7%, P < 0.053), and rate of urea N production (59.6 vs 49.2 g/d) but lower (P < 0.05) percentage of urea N produced that was returned to the ornithine cycle (15.03 vs 19.2 1%) than when fed LO. Methionine supplementation decreased daily urine N (41.2 vs 44.6 g, P = 0.10) and increased both the amount of N retained daily (27.9 vs 23.7 g, P < 0.089) and the percentage of N digested that was retained (40.4 vs 34.6%, P < 0.094). In summary, supplemental methionine met a specific dietary limitation by increasing the amount of digested N that was retained by the steers.

Urea flux in beef steers: effects of forage species and nitrogen fertilization.

The effects of two forage species and N levels on urea kinetics and whole-body N metabolism were evaluated in eight Angus steers (initial BW 217+/-15 kg). In a replicated, 4 x 4 Latin square design, steers were fed gamagrass (Tripsacum dactyloides L.) or switchgrass (Panicum virgatum L.), each of which had 56.2 (LO) or 168.5 (HI) kg of N fertilization per hectare. Diets provided adequate energy for 0.5 kg ADG. Nitrogen balance and urea kinetics were measured from d 22 to 27 of each period. Urine samples collected during intravenous infusion of bis 15N urea were used to calculate production and recycling of urea N from relative abundance of urea isotopomers. Jugular blood serum was analyzed for serum urea N (SUN). Gamagrass differed from switchgrass (P < 0.05) in daily DMI (4,273 vs 4,185 g), N intake (72 vs 67 g), DM digestibility (61.0 vs 63.6%), fecal N (30.6 vs 28.3 g/d), urine urea N (10.5 vs 8.0 g/d), and percentage of urinary N present as urea N (53.5 vs 40.0%). After adjustment for differences in N intake, fecal N still tended to be greater (P < 0.09) for gamagrass than for switchgrass. The LO differed from the HI (P < 0.01) in daily N intake (63 vs 76 g), DM digestibility (61.3 vs 63.3%), urine N (13.6 vs 25.9 g/d), and N retained as a percentage of N digested (57.3 vs 43.5%). Compared to switchgrass, gamagrass had greater SUN, N digestibility, and N digested as N level increased (forage x N level interactions, P < 0.05). As N level increased, N retention increased from 19.5 to 23.5 g/d in gamagrass and decreased from 20.5 to 18.1 g/d in switchgrass (interaction, P < 0.07). The HI group was greater than the LO intake group (P < 0.03) in endogenous production of urea N (44.4 vs 34.0 g/d), gut entry rate of urea N (31.6 vs 28.2 g/d), and the amount of urea N that re-entered the ornithine cycle (9.4 vs 7.9 g/d). However, the percentage of urea N entering the gastrointestinal tract that was recycled was constant among treatments (29.1%), indicating that almost 70% of the urea N that entered the gastrointestinal tract was potentially available for anabolic purposes of the steers as a component of microbial products that were absorbed or excreted in the feces. In summary, N levels affected N metabolism of steers more when they were fed gamagrass than when they were fed switchgrass. Although the absolute amounts of N moving through the system changed with variations in intake, the proportions remained similar, with a greater efficiency of N use at low N intakes.

Highly branched and tartaric acid-based water-borne resins

In this study, water-borne polyurethane resins were produced using poly(propylene-ethylene) copolymer triol, toluene diisocyanate, and hydrophilic monomers, dimethylol propionic acid and tartaric acid. The hydrophilic monomers were used separately. In either case, the ratio of isocyanate functional groups to the sum of hydroxyl groups of polyol and hydrophilic monomer was kept constant. The increase in the amount of hydrophilic monomer increased the hardness of resins when used as varnish. Tartaric acid resulted in higher hardness than dimethylol propionic acid. The dispersions made by using tartaric acid had much larger particle sizes than those of dimethylol propionic acid. In another set of experiments, the samples carrying the optimum properties from the two sets were mixed with methylol urea that served as crosslinker in the baking step. The physical and mechanical properties were determined by changing the weight percentages of the two types of samples in the mixture, and by changing the methylol urea percentage of the mixture which exhibited the maximum hardness. All samples showed superior impact resistance, adhesion, and flexibility. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 604–612, 2001

Tracer studies of urea kinetics in growing pigs: I. The effect of intravenous infusion of urea on urea recycling and the site of urea secretion into the gastrointestinal tract

Four gilts (average BW 80 kg) were used in the first experiment to study the effect of i.v. infusion of urea on urea kinetics by means of a radioisotope dilution technique. The pigs were fed twice daily 600 g of a cornstarch-based diet formulated to contain 16% CP by supplementation with isolated soy protein. Infusion of urea, compared with saline, increased (P < .05) plasma urea concentration, urea pool size, urea entry, urea excretion, and urea degradation rates; urea turnover rate and urea space were not affected (P > .05). Expressed as a percentage of the total entry rate, a lower (P < .05) percentage of urea was recycled in pigs infused with urea. The urea infused was almost completely excreted in urine, so there were no differences (P > .05) in N balance. In the second experiment, four gilts (average BW 40 kg), fitted with ileocecal reentrant cannulas, were used to determine whether the upper or the lower digestive tract represents the preferential site of urea secretion in pigs. Two pigs were fed twice daily 600 g of a cornstarch-based diet, formulated to contain 16% CP from soybean meal. The other two pigs were fed the same diet in which 15% cornstarch was replaced by beet pulp. After labeling the body urea pool of one pig on each treatment with [15N]urea, the reentrant cannulas were disconnected to prevent the flow of digesta from the small into the large intestine.(ABSTRACT TRUNCATED AT 250 WORDS)

Deactivation of Tannin in High Tannin Milo by Treatment with Urea1,2

Experiments were conducted to determine the effectiveness of urea in deactivating tannin in high tannin milo. High tannin milo (Pioneer B 815, 3.4±.3% tannin) was reconstituted with aqueous urea solutions to give combinations of 26, 30, and 34% moisture with 2, 3, and 4% urea (percentage of urea per dry weight of milo). All treatments were maintained at 25°C and were effective in deactivating tannin with no differences among moisture or urea content. The average rate of tannin deactivation was 68±2% d−1. Temperature affected rate of tannin deactivation in milo reconstituted to 30% moisture and 3% urea when stored at 25 or 60°C. Rate of tannin deactivation was 44±5 and 89±18% d−1 at 25 and 60°C, respectively. Tannin in high tannin milo can be deactivated rapidly and completely by reconstitution with aqueous urea. These studies demonstrate that tannin is deactivated completely under conditions where urea is an effective preservative of high moisture milo.

Sorbents used for removal of urea in the system of artificial kidney.

Three copolymers were made from the suspension polymerization of methyl acrylate, divinyl benzene and triallyl isocyanurate; acrylamide and N,N'-methylene-bis-acrylamide; and styrene and divinyl benzene. These copolymers were then converted into derivatives of hydrazides through several steps. They were used as polymeric sorbents. They sorbed in situ a little bit less than 40 mg. of urea per gram of sorbent at 37 degrees C, pH = 7.0-7.4 and the percentage of urea in the buffer solution being 130 mg%. The sorption of urea was related to the specific surface area of the sorbent, temperature of sorption and time of sorption, concentration of urea, pH value of solution etc. In order to find out whether the above-prepared derivatives of hydrazide can be used clinically as polymeric sorbents in artificial kidney system, the junior author carried out experiments with patient's dialysate as imitated to hemodialysis. From the results, it indicates the sorbents might be used in artificial kidney system because they sorbed the urea from hemodialysate as much as that of the pure urea in a buffer solution.

Formaldehyde treatment of concentrate diets for sheep. II.* Effect on urea synthesis and excretion

The synthesis of urea, its return to the gastrointestinal tract and excretion in the urine were studied in sheep given concentrate diets, untreated or treated with formaldehyde, containing four different protein levels. Rumen ammonia and plasma urea levels increased with protein level and decreased with formaldehyde treatment. Changes in urea excretion were closely related to changes in plasma urea levels. There was a relationship between urea synthesis and rumen ammonia levels, but differences in the amount of urea returned to the gastrointestinal tract did not follow a consistent pattern. When expressed as a percentage of urea synthesized, urea recycling decreased as protein level increased but tended to increase when the diets were treated. The results are consistent with an appreciable fraction of the nitrogen returned to the rumen being in forms other than urea. _________________ *Part I, Aust. J. Agric. Res., 28: 1055 (1977).

Nitrogen Components in the Digesta of Sheep Fed Corn Gluten Meal and Urea

Sixty-five lambs were used in a growth, blood composition and digestive tract contents nitrogen fractionation study. Fifty lambs were used to compare five rations in which supplemental nitrogen was furnished by either CGM or urea. The rations contained either 0, 10, 20, 30, of 40% of the total nitrogen from urea with the remaining portion of the supplementary nitrogen being supplied by CGM. A faster rate of gain was obtained from the rations in which 100 or 75% of the supplemental nitrogen was furnished by CGM, lending support to the idea that some preformed supplementary dietary protein is desirable for growth. Plasma amino acid levels varied considerably among treatments with trends toward lower levels of total essential amino acids in lambs fed the higher levels of dietary urea. High levels of dietary CGM tended to give increased plasma leucine while high levels of dietary urea resulted in increased plasma lysine. Fifteen lambs were fed the same five rations and sacrified after a 21-day feeding period. Digesta samples were taken from the reticulo-rumen, omasum, abomasum, duodenum, jejunum, ileum, cecum and colom. As the percentage of urea in the diet increased there was a decrease in the percentage of dietary nitrogen recovered in the rumen. Most endogenous nitrogen secretion occurred in the duodenum. Protein nitrogen decreased from the omasum to the jejunum and was accompanied by an increase in amino nitrogen in these same areas. Amino acid analyses, expressed as a molar percentage of the total, indicated that urea additions may change the percentage of certain essential amino acids in the abomasum.

Urea as a fertilizer. Ammonia evolution and brairding of wheat

1. Moderate percentages of urea are widely and successfully used in compound fertilizers but the use of large proportions may be accompanied by two disadvantages:(a) the loss of nitrogen as ammonia from surface applications,(b) the occurrence of toxic effects when urea and seeds are drilled together in soil. This paper shows that both these effects are consequences of the rapid hydrolysis of urea to ammonia and carbon dioxide.2. The effect on brairding of the presence of urea and of ammonium sulphate drilled with wheat seeds, and the loss of ammonia from top-dressings of the compounds on bare soils have been studied on a range of soils. Phytotoxicity was most pronounced in those conditions in which ammonia evolution was greatest. Thus, in a sandy soil, from which about 75% of the nitrogen of a top-dressing of urea was evolved as ammonia in our conditions, more than 15 lb. nitrogen as urea per acre reduced the braird of wheat seeds; while in a clay soil, from which only 10% of a top-dressing was lost as ammonia, up to 60 lb. nitrogen as urea per acre could be added before braird was reduced. Intermediate results were obtained with three more soils and ammonia evolution and brairding were always closely parallel.

乳製品のアミノ・カルボニル反応に関する研究

In order to establish a direct colorimetric method to estimate urea in milk, the α-isonitrosopropiophenone method was studied as follows: (1) The color of urea with α-isonitrosopropiophenone was stable in the dark, slightly stable under scattered light, and unstable under the direct rays of the sun (Tbale 1). (2) The regression coefficient in urea solution and milk were obtained with a 5% significance level (Tables 2 and 3). The relation between the reading in a Beckmann Spectro-phtometer (X) and content of urea in milk (Y), was indicated according to the following equation with a 5% significance level:Y=104.35X (3) The coefficient variation of this colorimetric and the standard urease method were 3.68 and 2.90, respectively, with a 5% significant level (Table 4). Therefore, by means of the colorimetric method described above, the content of urea in milk was determined as follows: (4) It appeared with a 0.1% significance level that the content of urea in milk is different for each cow (Table 5). (5) The percentage of urea in market milk was 14.02_??_18.37mg% with a 5% significance level obtained from 56 samples. The correlation coefficient between the color of milk heated to 120° for 1.5 hours and the content of urea in milk before heating was 0.0678_??_1.0278 with a 5% significance level. It is found that the content of urea in milk is probably a factor in the browning of heated milk which is different in each milk as shown by WEBB(26) (Fig. 1 and Table 7).

乳製品のアミノカルボニル反応に関する研究

緩和条件下の尿素-ラクトース系中に形成されるurea-lactoside生成の2, 3の条件を検討して次の結果を得た. (1) pH 3.6以下の酸性溶液中では速かにurea-lactosideが形成されるが,グルコース,ガラクトースでも同様である. (2) 酸の存在はurea-lactosideの生成を促進するが,この程度は燐酸,クエン酸が最も大で,塩酸,乳酸,酢酸の順に小となり, urea-glucosideの場合も同様である. 更に,この形成されたurea-lactosideの構造及び理化学的諸性質の検討を行った.即ち, β-グルコシダーゼによる被分解能,赤外線吸収スペクトル等の結果から,本物質はN-urea-α-lactosideの構造を有し,又, ο-ジニトロベンゼン, cysteine-carbazol, SELIWANOFF反応陰性等の成績から,本物質はAMADORI転位生成物とは認められないことを推定した. 最後に,本物質の尿素-ラクトース系のアミノ カルボニル反応における褐色化に対する意義について考察を加えた.

The Total Molecular Concentration of Uremic Bloodserum and its Urea Percentage

The Total Molecular Concentration of Uremic Bloodserum and its Urea Percentage