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Livestock excreta deposition on concrete farmyards has been identified as an important source of ammonia (NH3) emissions from agriculture. The objective of this study was to quantify the effect of urine application rate and four cleaning strategies on NH3 emissions from excreta deposited on a concrete yard. Three experiments were conducted on a concrete yard over a three week period in August 2016. Experiment 1 consisted of 1 kg dung applied with either (i) 0.67 l urine (1:0.67), (ii) 1 l urine (1:1) or (iii) 2 l urine (1:2). In experiments 2 and 3 the treatments were (i) non cleaned control, (ii) cleaned after 1 h and (iii) cleaned after 3 h. The cleaning method in experiment 2 and 3 was pressure washing and scraping, respectively. Ammonia emissions were measured using wind-tunnels for 72 h. Cumulative NH3 emissions increased linearly with increasing urine N rate and emission factors ranged from 46% to 67% of urine urea-N applied and from 22% to 29% of total N applied. In experiment 2 and 3 the greatest reduction in cumulative NH3 emissions was obtained from pressure washing at 1 h which reduced emissions compared to the non-cleaned control by 91%. Pressure washing at 3 h reduced emissions by 80% while scraping after 1 h and 3 h reduced emissions by 78% and 54%, respectively. Farmers should be encouraged to clean their animal handling yards as soon as possible after use in order to maximise reductions in NH3 emissions from this source.

Background The enriched nitrogenous compounds in the dairy farms negatively affect the surrounding soil quality and air condition. The objective of this study is to investigate the transcriptomes of five key tissues involved in nitrogen metabolism and their changes under different diets to elucidate the molecular regulatory mechanisms of urine urea nitrogen (UUN) yield, one of the indicators of nitrogenous compound secretion of dairy cows. Results Cows fed high quality forage-based diet had lower UUN content and UUN yield, compared to those fed low quality forage (crop byproducts) based diets. From the transcriptomes of rumen, duodenum , jejunum , liver and udder, key driver genes and their UUN yield-associated functional gene networks were identified. In addition, the functional networks and expression of key drivers in various tissues (such as S100A8, CA1 and BPIFA2C in the duodenum; A2ML1, HMGCS2 and S100A12 in the jejunum; CYP2B6 and GLYCAM1 in the liver; APOE in the udder) changed in the cows fed crop byproducts based diet, which might be the predominant molecules to drive the increase UUN yield in these cows. Conclusion The information suggested that gut, liver and udder play important roles in regulating UUN yield, which could regulate nitrogen excretion waste. These findings provide fundamental information on future nutritional intervention strategies to reduce the UUN yield from dairy cows fed human inedible crop byproducts, which is vital for a sustainable and environmentally friendly dairy industry.

espanolIntroduccion: la restriccion proteica es fundamental en el manejo de la enfermedad renal cronica. Objetivo: evaluamos la utilidad de la medicion de nitrogeno ureico urinario como marcador de restriccion proteica. Metodos: participantes jovenes sanos fueron divididos aleatoriamente en dos grupos. Un grupo recibio una dieta con 30 kcal/dia/kg peso corporal y 1 g/proteina/dia/kg peso corporal y el otro recibio una dieta con la misma cantidad de calorias pero con 0,6 g/kg peso corporal de proteina. Al inicio, a los siete y a los 14 dias, los participantes respondieron una encuesta dietaria de recordatorio de 24 horas. Ademas, recolectaron orina de 24 horas y se les tomo una muestra aislada de orina al comienzo y a los 14 dias de la intervencion para medir creatinina y nitrogeno ureico. Resultados: cuarenta y un participantes de 29 ± 5 anos completaron el estudio. El grupo que consumio 0,6 g/kg de proteinas redujo su ingesta proteica de 0,88 ± 0,06 a 0,59 ± 0,05 g/kg/dia durante la intervencion. En este grupo se observo una reduccion significativa en la excrecion urinaria de nitrogeno ureico en 24 horas. No se observo tal reduccion en el grupo que consumio 1 g/kg de proteinas. La tasa de probabilidad de detectar una reduccion en la ingesta proteica en las encuestas dietarias, cuando se observaba una disminucion en la excrecion urinaria de nitrogeno ureico/mg creatinina de 24 horas, fue de 5,75 (intervalos de confianza de 95% = 1,29-25,55, p = 0,02). No hubo cambios significativos en la excrecion de nitrogeno ureico en las muestras aisladas de orina. Conclusion: las mediciones repetidas de nitrogeno ureico urinario en 24 horas son un marcador de restriccion dietaria de proteinas. EnglishBackground: protein restriction is the mainstay of dietary management of chronic kidney disease. Aim: to assess the usefulness of urine urea nitrogen measurement as a marker of protein restriction. Methods: healthy young participants were randomly divided in two groups. During 14 days, one group received a diet containing 30 kcal/kg body weight and 1 g protein/kg body weight and the other group received a diet with the same amount of calories and 0.6 g/kg of proteins. At baseline, seven days and 14 days, 24 h dietary recalls were answered by the participants. They collected 24 hour urine and provided spot urine samples at baseline and at the end of the intervention, to measure creatinine and urea nitrogen. Results: forty-one participants aged 29 ± 5 years completed the follow-up. According to 24h dietary recalls, the group receiving 0.6 g/kg protein reduced significantly the protein intake during the intervention from 0.88 ± 0.06 to 0.59 ± 0.05 g/kg/day. A significant reduction in 24 h urea nitrogen excretion was also observed in this group. In the group receiving 1 g/kg of protein, no significant changes in 24 h urea nitrogen excretion were observed. Among all participants, the odds ratio of observing a reduction in protein intake in the dietary survey was 5.75 (95% confidence intervals 1.29-25.55, p = 0.02), when a reduction in 24 h urea nitrogen excretion corrected by creatinine was observed. No changes were observed in urea nitrogen excretion in spot urine samples. Conclusions: repeated urea nitrogen excretion measured in 24 h urine samples can be a reliable indicator of dietary protein restriction.

Urine urea–creatinine ratio (U:C) often is used as an index of nutritional status of wild mammals, especially because urine can be collected from snow, providing a non-invasive index of nutrition. The rate of creatinine excretion has been assumed to be relatively stable; thus, creatinine concentration is used to normalize urea concentrations and control for dilution in snow. We present data from captive wolves (Canis lupus) to test how much variation in U:C is due to variation in urea vs. creatinine in relation to time since feeding. We found that U:C increases for ∼18 hours post-feeding but that this variation is primarily due to the 5-fold decrease in creatinine rather than the 2-fold increase in urea concentration. It is not clear what governs the variable creatinine concentrations in urine. Until a fuller understanding of this metabolite is achieved, ecological studies employing this nutritional index should report urea and creatinine values as well as the ratio. Physiological studies should ...

Renal urea conservation was evaluated in Corriedale ewes during late pregnancy and lactation. Glomerular filtration, renal plasma flow and urea clearance were significantly reduced both states compared with control sheep. Filtered load of urea and urine urea elimination were significantly reduced during lactation (−46% and −45%, respectively, vs. controls). No changes were noted in fractional excretion of urea. Therefore, Corriedale ewes restrict urine urea losses during lactation by reducing glomerular filtration. During late pregnancy, urea sparing is less marked. Key words: Renal functions, urea, pregnancy, lactation, sheep

Nitrogen excretion was studied in the aquatic caecilian Typhlonectes natans by analyzing samples of the bathing medium over an 8-h period for total ammonia ($T_{amm}$: NH₃ + $NH_{4}^{+}$) and urea. Total ammonia was excreted at a rate of 0.35 μM · 10g⁻¹ · h⁻¹, while urea was excreted at a rate of 0.19 μM · 10g⁻¹ · h⁻¹. When excretion is expressed in molar equivalents of nitrogen, ammonia-N excretion was 0.35 μatm N · 10g⁻¹ · h⁻¹ while urea-N excretion was 0.38 μatm N · 10 g⁻¹ · h⁻¹. These latter values uwere not significantly different. Plasma $T_{amm}$ concentration was 1.3 mM, while plasma urea concentration was 4.4 mM Urine $T_{amm}$ concentration was 3.8 mM, while urine urea concentration was 2.7 mM. Partitioning $T_{amm}$ excretion between skin and kidneys found 1.11 μM · 10 g⁻¹ · h⁻¹ ammonia excreted across the skin. The kidneys contributed 0.09 μM · 10 g⁻¹ h⁻¹, or less than 8%. Skin urea excretion rate was 0.21 μM · 10 g⁻¹ · h⁻¹, while the kidneys accounted for 0.08 μM · 10 g⁻¹ · h⁻¹, or less than 28%.

Objective: to reveal the features of perioperative metabolic disturbances in patients with lung cancer after pulmonectomy and a possibility of their correction with perioperative «Standard» formula sipping and with postoperative intravenous cytoflavin. Subjects and methods. The paper presents the results of a prospective randomized study of the efficiency of correction of metabolic disturbances in patients with lung cancer with perioperative enteral «Standard» formula sipping (5 days before surgery and 12 days after surgery). The study was conducted in 326 men aged 36 to 68 years. Arterial blood metabolic parameters (glucose, lactate, and pyruvate) and daily urine urea were estimated. Results. There was an association of preoperative metabolic disturbances with body mass index (BMI). Inclusion of sipping into perioperative therapy did not exert a considerable impact on the cause of postoperative metabolic disturbances. Key words: lung cancer, pul-monectomy, body mass index, sipping, cytoflavin.

A kinetic assay for urine urea which employs the reaction with diacetylmonoxime at 37°C and undiluted urine was developed. Reaction conditions were optimized using the Monarch centrifugal analyser to produce an assay with the linearity to 450 mmol/L urea, and CVs of 2·3% and 2·5% within-batch and 4·6% and 3·3% between-batch at urea concentrations of 75·9 and 162·7 mmol/L, respectively; recoveries of 98·5% to 99·5% were obtained with the addition of the equivalent of 95 and 190 mmol/L urea. Comparisons were made with one urine urea method employing diacetylmonoxime with dialysis and two enzymatic methods which all involve a sample pre-dilution stage. The urine samples used for the method comparisons did not contain preservatives. However, a range of urine preservatives and a selection of possible interfering metabolites were shown to have no significant effect on the recovery of urea in the assay.

The work aimed to evaluate the concentrations of plasmatic and urine urea, the balance of nitrogen compounds, and to estimate the protein requirements for maintenance. Equations recommended by the American and British systems were used in four bovine and four bubaline steers, with initial average weight of 461.19 ± 7.59 and 455.44 ± 7.85 kg for cattle and buffaloes, respectively, distributed into two 4 x 4 Latin squares. The treatments consisted of different levels of concentrate (0.0; 24.0; 48.0; and 72.0%) composed of cracked corn, soybean meal, mineral salt, and Tifton-grass hay. Each period lasted 21 days, being 14 for adaptation and seven for collection. Samples of feces and urine ( spot ) were taken to estimate the production of fecal dry matter and urine volume. Interactions were observed between the species for N intake (NC), urine-N (UN) g kg -0.75 and urinary urea (UU); no interactions occurred for fecal-N (NF), absorbed-N (NABS), UN (g d -1 ), balance of N (BN) and plasmatic urea (UP). Regardless of the difference observed between the species, the response variables increased linearly as functions of the growing levels of concentrate that resulted in positive BN. The estimate of metabolizable protein maintenance requirements for cattle and buffaloes differs between the American and British systems.

Hypermetabolic burn patients are frequently in negative nitrogen balance despite provision of estimated caloric needs. We studied 18 thermally injured adult patients in order to evaluate the relationship of burn wound size to urea production and nitrogen balance. We selected data from 147 patient-days when the patients received 100 +/- 25% of their estimated caloric needs. Three significantly different burn size groups (by body surface area [BSA]) were identified by calculation of the catabolic index (CI): group 1, 0-10% BSA (CI = -0.1); group 2, 11-30% BSA (CI = 6.4); and group 3,31-60% BSA (CI = 10.5). The urine urea nitrogen (UUN) for groups 1,2, and 3 was 11.1, 18.9, and 25.3 gm/day, and nitrogen balance was 1.0, -3.9, and -5.8 gm/day, respectively. When nitrogen was given in a calorie:nitrogen ratio of 150:1, only those patients in group I were able to achieve positive balance. We conclude that large burn wounds are associated with increased ureagenesis and impaired nitrogen retention. The protein intake, at the customary calorie:nitrogen ratio of 150:1, may not provide adequate nitrogen to achieve equilibrium, even when energy demands have been met, in patients with burn wounds greater than 10% BSA.

1. The sources of turbidity in directly nesslerized blood and urine filtrates have been discussed and a new method of nesslerization has been presented which eliminates turbidities. The new procedure has been compared in a quantitative manner with several methods. 2. A procedure for the determination of blood and urine urea and for urine ammonia has been presented, incorporating the new nesslerization technic.

A clinical rapid micro or super-micro method for urea is described, which will enable one to determine urea in a minute amount of urine, such as 0.1 c. c. or smaller amounts.

In some children, small residual bladder volumes may predispose to urinary tract infections but current methods for determining small residual urine volumes are relatively inaccurate and impractical. A urine-urea exchange procedure was developed to determine full-bladder volume prior to voiding. Subtracting the volume voided from the full-bladder volume gives the residual volume. This procedure consists of injecting suprapubically a small volume of concentrated urea solution, and measuring the increase in osmolality; the larger the urine volume prior to the injection, the smaller will be the increase in urine osmolality following the injection. A mathematical error analysis to determine the overall statistical standard deviation of the full-bladder volume, the voided volume and the residual volume showed the standard deviation of each to be 0.929cc, 0.401cc and 1.33cc, respectively. With trials, using an in vitro laboratory model, the mean error of the full-bladder volume was 1.1cc and the mean error of the residual volume 1.14cc. In vivo dog experiments confirmed that the procedure is safe and practical. Clinical trials have been started.

Temperature regulation and water economy were studied in two species of spiny mice, Acomys russatus and Acomys cahirinus. Both species share the same desert habitat in Israel, but A. russatus is active during the day and A. cahirinus is nocturnal. It was shown that A. russatus was better able to maintain its normal body temperature (TB) when exposed to high ambient temperatures (TA) and survived temperatures as high as 42.5°C. On the other hand, TA 40°C was lethal to A. cahirinus. Mean minimal metabolism of A. russatus was 34.5 per cent lower than the value predicted from body weight, and that of A. cahirinus was 13.5 per cent lower. A. russatus had no thermoneutral zone, oxygen consumption being minimal at TA 30°C. A . cahirinus had a narrow thermoneutral zone between 27 and 32.5°C TA. High ratios of evaporative water loss per milliliter of oxygen consumed were measured in both species; at 30°C it was 2.3 mg H2O/ml O2 in A . russatus and 1.9 mg H2O/ml O2 in A. cahirinus. When restrained at 30°C, 60 to 70 per cent of evaporation was from the skin. Maximum urine urea concentration in both species was 4700 to 4800 mM, among the highest recorded for mammals. Maximum chloride concentration was higher in the urine of A. russatus and amounted to 1500 mN, almost twice that of A. cahirinus. Accordingly, the capacity to utilize salt solutions for drinking was higher in A. russatus, which could drink sea water or NaCl solution as concentrated as 0.9 N. At 30°C, both species, when deprived of drinking water, failed to survive on a diet of barley. A. russatus could be considered physiologically better adapted for a diurnal existence than A. cahirinus, both in its ability to cope with high ambient temperatures and in its capacity to derive water from salty, succulent plants.

This is the first of a short series of papers, the outcome of an attempt to draw quantitative structural deductions from functional results. The few methods used are discussed and criticized only in reference to the question as to whether the results give information in regard to the amount of secreting tissue in the kidney. This narrow point of view has been adopted because the purpose of the inquiry is entirely utilitarian and clinical. All manifestations of renal function have an intrinsic interest from the standpoint of physiology, but it is maintained that only those from which we can draw quantitative conclusions about the amount of tissue in the kidney are of immediate and practical clinical importance. Such an idea is foreign to nearly all the recent work on this subject. Nevertheless, from the time of Bright up to about the beginning of the last decade, the hope that functional