The incremental yield of prenatal exome sequencing over chromosome microarray for congenital heart abnormalities: A systematic review and meta-analysis.

OBJECTIVES: To determine the incremental yield of prenatal exome sequencing (PES) over standard testing in fetuses with an isolated congenital heart abnormality (CHA), CHA associated with extra-cardiac malformations (ECMs) and CHA dependent upon anatomical subclassification. METHODS: A systematic review of the literature was performed using MEDLINE, EMBASE, Web of Science and grey literature January 2010-February 2023. Studies were selected if they included greater than 20 cases of prenatally diagnosed CHA when standard testing (QF-PCR/chromosome microarray/karyotype) was negative. Pooled incremental yield was determined. PROSPERO CRD 42022364747. RESULTS: Overall, 21 studies, incorporating 1957 cases were included. The incremental yield of PES (causative pathogenic and likely pathogenic variants) over standard testing was 17.4% (95% CI, 13.5%-21.6%), 9.3% (95% CI, 6.6%-12.3%) and 35.9% (95% CI, 21.0%-52.3%) for all CHAs, isolated CHAs and CHAs associated with ECMs. The subgroup with the greatest yield was complex lesions/heterotaxy; 35.2% (95% CI 9.7%-65.3%). The most common syndrome was Kabuki syndrome (31/256, 12.1%) and most pathogenic variants occurred de novo and in autosomal dominant (monoallelic) disease causing genes (114/224, 50.9%). CONCLUSION: The likelihood of a monogenic aetiology in fetuses with multi-system CHAs is high. Clinicians must consider the clinical utility of offering PES in selected isolated cardiac lesions.

A pilot study evaluating GSK1070806 inhibition of interleukin-18 in renal transplant delayed graft function.

INTRODUCTION: Delayed graft function (DGF) following renal transplantation is a manifestation of acute kidney injury (AKI) leading to poor long-term outcome. Current treatments have limited effectiveness in preventing DGF. Interleukin-18 (IL18), a biomarker of AKI, induces interferon-γ expression and immune activation. GSK1070806, an anti-IL18 monoclonal antibody, neutralizes activated (mature) IL18 released from damaged cells following inflammasome activation. This phase IIa, single-arm trial assessed the effect of a single dose of GSK1070806 on DGF occurrence post donation after circulatory death (DCD) kidney transplantation. METHODS: The 3 mg/kg intravenous dose was selected based on prior studies and physiologically based pharmacokinetic (PBPK) modeling, indicating the high likelihood of a rapid and high level of IL18 target engagement when administered prior to kidney allograft reperfusion. Utilization of a Bayesian sequential design with a background standard-of-care DGF rate of 50% based on literature, and confirmed via extensive registry data analyses, enabled a statistical efficacy assessment with a minimal sample size. The primary endpoint was DGF frequency, defined as dialysis requirement ≤7 days post transplantation (except for hyperkalemia). Secondary endpoints included safety, pharmacokinetics and pharmacodynamic biomarkers. RESULTS: GSK1070806 administration was associated with IL18-GSK1070806 complex detection and increased total serum IL18 levels due to IL18 half-life prolongation induced by GSK1070806 binding. Interferon-γ-induced chemokine levels declined or remained unchanged in most patients. Although the study was concluded prior to the Bayesian-defined stopping point, 4/7 enrolled patients (57%) had DGF, exceeding the 50% standard-of-care rate, and an additional two patients, although not reaching the protocol-defined DGF definition, demonstrated poor graft function. Six of seven patients experienced serious adverse events (SAEs), including two treatment-related SAEs. CONCLUSION: Overall, using a Bayesian design and extensive PBPK dose modeling with only a small sample size, it was deemed unlikely that GSK1070806 would be efficacious in preventing DGF in the enrolled DCD transplant population. TRIAL REGISTRATION: NCT02723786.

Nitrogen use efficiency and nitrous oxide emissions from five UK fertilised grasslands.

Intensification of grasslands is necessary to meet the increasing demand of livestock products. The application of nitrogen (N) on grasslands affects the N balance therefore the nitrogen use efficiency (NUE). Emissions of nitrous oxide (N2O) are produced due to N fertilisation and low NUE. These emissions depend on the type and rates of N applied. In this study we have compiled data from 5 UK N fertilised grassland sites (Crichton, Drayton, North Wyke, Hillsborough and Pwllpeiran) covering a range of soil types and climates. The experiments evaluated the effect of increasing rates of inorganic N fertiliser provided as ammonium nitrate (AN) or calcium ammonium nitrate (CAN). The following fertiliser strategies were also explored for a rate of 320 kg N ha-1: using the nitrification inhibitor dicyandiamide (DCD), changing to urea as an N source and splitting fertiliser applications. We measured N2O emissions for a full year in each experiment, as well as soil mineral N, climate data, pasture yield and N offtake. N2O emissions were greater at Crichton and North Wyke whereas Drayton, Hillsborough and Pwllpeiran had the smallest emissions. The resulting average emission factor (EF) of 1.12% total N applied showed a range of values for all the sites between 0.6 and 2.08%. NUE depended on the site and for an application rate of 320 kg N ha-1, N surplus was on average higher than 80 kg N ha-1, which is proposed as a maximum by the EU Nitrogen Expert Panel. N2O emissions tended to be lower when urea was applied instead of AN or CAN, and were particularly reduced when using urea with DCD. Finally, correlations between the factors studied showed that total N input was related to Nofftake and Nexcess; while cumulative emissions and EF were related to yield scaled emissions.

The contribution of cattle urine and dung to nitrous oxide emissions: Quantification of country specific emission factors and implications for national inventories.

Urine patches and dung pats from grazing livestock create hotspots for production and emission of the greenhouse gas, nitrous oxide (N2O), and represent a large proportion of total N2O emissions in many national agricultural greenhouse gas inventories. As such, there is much interest in developing country specific N2O emission factors (EFs) for excretal nitrogen (EF3, pasture, range and paddock) deposited during gazing. The aims of this study were to generate separate N2O emissions data for cattle derived urine and dung, to provide an evidence base for the generation of a country specific EF for the UK from this nitrogen source. The experiments were also designed to determine the effects of site and timing of application on emissions, and the efficacy of the nitrification inhibitor, dicyandiamide (DCD) on N2O losses. This co-ordinated set of 15 plot-scale, year-long field experiments using static chambers was conducted at five grassland sites, typical of the soil and climatic zones of grazed grassland in the UK. We show that the average urine and dung N2O EFs were 0.69% and 0.19%, respectively, resulting in a combined excretal N2O EF (EF3), of 0.49%, which is <25% of the IPCC default EF3 for excretal returns from grazing cattle. Regression analysis suggests that urine N2O EFs were controlled more by composition than was the case for dung, whilst dung N2O EFs were more related to soil and environmental factors. The urine N2O EF was significantly greater from the site in SW England, and significantly greater from the early grazing season urine application than later applications. Dycandiamide reduced the N2O EF from urine patches by an average of 46%. The significantly lower excretal EF3 than the IPCC default has implications for the UK's national inventory and for subsequent carbon footprinting of UK ruminant livestock products.

Risk of pre-eclampsia in women taking metformin: a systematic review and meta-analysis.

AIMS: To perform meta-analyses of studies evaluating the risk of pre-eclampsia in high-risk insulin-resistant women taking metformin prior to, or during pregnancy. METHODS: A search was conducted of the Medline, EMBASE, Web of Science and Scopus databases. Both randomized controlled trials and prospective observational cohort studies of metformin treatment vs. placebo/control or insulin either prior to or during pregnancy were selected. The main outcome measure was the incidence of pre-eclampsia in each treatment group. RESULTS: Overall, in five randomized controlled trials comparing metformin treatment (n = 611) with placebo/control (n = 609), no difference in the risk of pre-eclampsia was found [combined/pooled risk ratio (RR), 0.86 (95% CI 0.33-2.26); P = 0.76; I2  = 66%]. Meta-analysis of four cohort studies again showed no significant effect [RR, 1.21 (95% CI 0.56-2.61); P = 0.62; I2  = 30%]. A meta-analysis of eight randomized controlled trials comparing metformin (n = 838) with insulin (n = 836), however, showed a reduced risk of pre-eclampsia with metformin [RR, 0.68 (95% CI 0.48-0.95); P = 0.02; I2  = 0%]. No heterogeneity was present in the metformin vs. insulin analysis of randomized controlled trials, whereas high levels of heterogeneity were present in studies comparing metformin with placebo/control. Pre-eclampsia was a secondary outcome in most of the studies. The mean weight gain from time of enrolment to delivery was lower in the metformin group (P = 0.05, metformin vs. placebo; P = 0.004, metformin vs. insulin). CONCLUSIONS: In studies randomizing pregnant women to glucose-lowering therapy, metformin was associated with lower gestational weight gain and a lower risk of pre-eclampsia compared with insulin.

Pancreatic allograft thrombosis: Suggestion for a CT grading system and management algorithm.

Pancreatic allograft thrombosis (PAT) remains the leading cause of nonimmunologic graft failure. Here, we propose a new computed tomography (CT) grading system of PAT to identify risk factors for allograft loss and outline a management algorithm by retrospective review of consecutive pancreatic transplantations between 2009 and 2014. Triple-phase CT scans were graded independently by 2 radiologists as grade 0, no thrombosis; grade 1, peripheral thrombosis; grade 2, intermediate non-occlusive thrombosis; and grade 3, central occlusive thrombosis. Twenty-four (23.3%) of 103 recipients were diagnosed with PAT (including grade 1). Three (2.9%) grafts were lost due to portal vein thrombosis. On multivariate analysis, pancreas after simultaneous pancreas-kidney transplantation/solitary pancreatic transplantation, acute rejection, and CT findings of peripancreatic edema and/or inflammatory change were significant risk factors for PAT. Retrospective review of CT scans revealed more grade 1 and 2 thromboses than were initially reported. There was no significant difference in graft or patient survival, postoperative stay, or morbidity of recipients with grade 1 or 2 thrombosis who were or were not anticoagulated. Our data suggest that therapeutic anticoagulation is not necessary for grade 1 and 2 arterial and grade 1 venous thrombosis. The proposed grading system can assist clinicians in decision-making and provide standardized reporting for future studies.

Donors With Immune Thrombocytopenia: Do They Pose a Risk to Transplant Recipients?

Transplant-mediated alloimmune thrombocytopenia (TMAT) from donors with immune thrombocytopenia (ITP) can result in significant bleeding complications in the recipient. The risk to a recipient of TMAT if they receive an organ from a donor with ITP is unknown. The outcomes of recipients of organs from deceased donors with ITP recorded in the UK Transplant Registry between 2000 and 2015 were reviewed. Twenty-one deceased organ donors had a predonation diagnosis of ITP. These donors were significantly more likely to have died from intracranial hemorrhage than were all other deceased organ donors (85% vs. 57%, p < 0.001). Organs from donors with ITP resulted in 49 organ transplants (31 kidney, 14 liver, four heart), with only one case of TMAT, which occurred in a liver transplant recipient and resulted in death from bleeding complications 18 days posttransplantation. The recipient of a kidney from the same organ donor was not affected. Unadjusted 5-year patient and graft survival was significantly worse for liver transplant recipients from donors with ITP compared with liver transplant recipients from donors without ITP (64% vs. 85%, p = 0.012). Organs from donors with ITP may be considered for transplantation, but livers should be used with caution.

Improving and disaggregating N2O emission factors for ruminant excreta on temperate pasture soils.

Cattle excreta deposited on grazed grasslands are a major source of the greenhouse gas (GHG) nitrous oxide (N2O). Currently, many countries use the IPCC default emission factor (EF) of 2% to estimate excreta-derived N2O emissions. However, emissions can vary greatly depending on the type of excreta (dung or urine), soil type and timing of application. Therefore three experiments were conducted to quantify excreta-derived N2O emissions and their associated EFs, and to assess the effect of soil type, season of application and type of excreta on the magnitude of losses. Cattle dung, urine and artificial urine treatments were applied in spring, summer and autumn to three temperate grassland sites with varying soil and weather conditions. Nitrous oxide emissions were measured from the three experiments over 12months to generate annual N2O emission factors. The EFs from urine treated soil was greater (0.30-4.81% for real urine and 0.13-3.82% for synthetic urine) when compared with dung (-0.02-1.48%) treatments. Nitrous oxide emissions were driven by environmental conditions and could be predicted by rainfall and temperature before, and soil moisture deficit after application; highlighting the potential for a decision support tool to reduce N2O emissions by modifying grazing management based on these parameters. Emission factors varied seasonally with the highest EFs in autumn and were also dependent on soil type, with the lowest EFs observed from well-drained and the highest from imperfectly drained soil. The EFs averaged 0.31 and 1.18% for cattle dung and urine, respectively, both of which were considerably lower than the IPCC default value of 2%. These results support both lowering and disaggregating EFs by excreta type.

Reducing nitrous oxide emissions by changing N fertiliser use from calcium ammonium nitrate (CAN) to urea based formulations.

The accelerating use of synthetic nitrogen (N) fertilisers, to meet the world's growing food demand, is the primary driver for increased atmospheric concentrations of nitrous oxide (N2O). The IPCC default emission factor (EF) for N2O from soils is 1% of the N applied, irrespective of its form. However, N2O emissions tend to be higher from nitrate-containing fertilisers e.g. calcium ammonium nitrate (CAN) compared to urea, particularly in regions, which have mild, wet climates and high organic matter soils. Urea can be an inefficient N source due to NH3 volatilisation, but nitrogen stabilisers (urease and nitrification inhibitors) can improve its efficacy. This study evaluated the impact of switching fertiliser formulation from calcium ammonium nitrate (CAN) to urea-based products, as a potential mitigation strategy to reduce N2O emissions at six temperate grassland sites on the island of Ireland. The surface applied formulations included CAN, urea and urea with the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) and/or the nitrification inhibitor dicyandiamide (DCD). Results showed that N2O emissions were significantly affected by fertiliser formulation, soil type and climatic conditions. The direct N2O emission factor (EF) from CAN averaged 1.49% overall sites, but was highly variable, ranging from 0.58% to 3.81. Amending urea with NBPT, to reduce ammonia volatilisation, resulted in an average EF of 0.40% (ranging from 0.21 to 0.69%)-compared to an average EF of 0.25% for urea (ranging from 0.1 to 0.49%), with both fertilisers significantly lower and less variable than CAN. Cumulative N2O emissions from urea amended with both NBPT and DCD were not significantly different from background levels. Switching from CAN to stabilised urea formulations was found to be an effective strategy to reduce N2O emissions, particularly in wet, temperate grassland.

Machine Perfusion of Donor Livers for Transplantation: A Proposal for Standardized Nomenclature and Reporting Guidelines.

With increasing demand for donor organs for transplantation, machine perfusion (MP) promises to be a beneficial alternative preservation method for donor livers, particularly those considered to be of suboptimal quality, also known as extended criteria donor livers. Over the last decade, numerous studies researching MP of donor livers have been published and incredible advances have been made in both experimental and clinical research in this area. With numerous research groups working on MP, various techniques are being explored, often applying different nomenclature. The objective of this review is to catalog the differences observed in the nomenclature used in the current literature to denote various MP techniques and the manner in which methodology is reported. From this analysis, we propose a standardization of nomenclature on liver MP to maximize consistency and to enable reliable comparison and meta-analyses of studies. In addition, we propose a standardized set of guidelines for reporting the methodology of future studies on liver MP that will facilitate comparison as well as clinical implementation of liver MP procedures.

Preimplant Normothermic Liver Perfusion of a Suboptimal Liver Donated After Circulatory Death.

Livers retrieved after circulatory death are associated with an increased incidence of primary nonfunction, early allograft dysfunction, and biliary strictures. The authors report a case of preimplant normothermic perfusion of a suboptimal liver from a 57-year-old donor after circulatory death who had been hospitalized for 9 days; predonation alanine transaminase level was 63 IU/L, and the period from withdrawal of life-supporting treatment to circulatory arrest was 150 minutes. After 5 hours of static cold storage, the liver was subject to normothermic machine perfusion with a plasma-free red cell-based perfusate. Perfusate lactate level fell from 7.2 to 0.3 mmol/L within 74 minutes of ex situ perfusion, at which point perfusate alanine transaminase level was 1152 IU/L and urea concentration was 9.4 mmol/L. After 132 minutes, normothermic perfusion was stopped and implantation begun. After transplantation, the patient made an uneventful recovery and was discharged on day 8; liver biochemistry was normal by day 19 and has remained normal thereafter. Donor common bile duct excised at implantation showed preservation of peribiliary glands, and cholangiography 6 months posttransplantation showed no evidence of cholangiopathy. Preimplant ex situ normothermic perfusion of the liver appears to be a promising way to evaluate a marginal liver before transplantation and may modify the response to ischemia.

The BH3-only protein BIM contributes to late-stage involution in the mouse mammary gland.

After cessation of lactation, involution of the mouse mammary gland proceeds in two distinct phases, a reversible and an irreversible one, which leads to the death and removal of alveolar cells. Cell death is preceded by the loss of STAT5 activity, which abrogates cell differentiation and gain of STAT3 activity. Despite early observations implicating BCL2 (B cell lymphoma 2) family proteins in this process, recent evidence suggests that STAT3-controlled cathepsin activity is most critical for cell death at the early stage of involution. Somewhat surprisingly, this cell death associates with but does not depend on the activation of pro-apoptotic effector caspases. However, transgenic overexpression of BCL2, that blocks caspase activation, delays involution while conditional deletion of BclX accelerates this process, suggesting that BCL2 family proteins are needed for the effective execution of involution. Here, we report on the transcriptional induction of multiple pro-apoptotic BCL2 family proteins of the 'BH3-only' subgroup during involution and the rate-limiting role of BIM in this process. Loss of Bim delayed epithelial cell clearance during involution after forced weaning in mice, whereas the absence of related Bmf had minor and loss of Bad or Noxa no impact on this process. Consistent with a contribution of BCL2 family proteins to the second wave of cell death during involution, loss of Bim reduced the number of apoptotic cells in this irreversible phase. Notably, the expression changes observed within the BCL2 family did not depend on STAT3 signalling, in line with its initiating role early in the process, but rather appear to result from relief of repression by STAT5. Our findings support the existence of a signalling circuitry regulating the irreversible phase of involution in mice by engaging BH3-only protein-driven mitochondrial apoptosis.

Postoperative CT in pancreas transplantation.

AIM: To examine the usage and value of computed tomography (CT) following simultaneous pancreas and kidney (SPK) transplantation. MATERIALS AND METHODS: Indications for postoperative CT, key findings, and their influence on management were determined by retrospective analysis. RESULTS: Ninety-eight patients underwent 313 CT examinations. Common indications for the examinations included suspected intra-abdominal collection (31.1%) and elevated serum amylase/lipase (24.1%). CT findings most frequently showed non-specific mild inflammation (27.6%), a normal scan (17.1%) and fluid collections (16.3%). High capillary blood glucose (CBG) was associated with resultant CT demonstration of graft vascular abnormalities, but otherwise, particular clinical indications were not associated with specific CT findings. CONCLUSION: Clinical findings in patients with SPK transplants are non-specific. The pattern of abnormalities encountered is significantly different to those seen in native pancreatic disease and demands a tailored protocol. CT enables accurate depiction of vascular abnormalities and fluid collections, thus reducing the number of surgical interventions that might otherwise be required. Elevated CBG should prompt urgent CT to exclude potentially reversible vascular complications.

When one becomes more: minimum renal artery length in laparoscopic live donor nephrectomy.

BACKGROUND: Laparoscopic donor nephrectomy may convert short main arteries into multiple arteries, increasing the technical challenge of implantation. We evaluated our experience to identify factors predictive of multiple arteries after laparoscopic nephrectomy. METHODS: All laparoscopic nephrectomies from the start of our program in November 2002 until June 2013 were studied, and preoperative imaging reviewed for donor artery length and multiplicity together with operative findings. RESULTS: A total of 287 consecutive laparoscopic live donor nephrectomies (64 right and 223 left nephrectomies) were studied. Renal artery length was measured from preoperative donor magnetic resonance or computed tomography angiogram and nephrectomy performed using a laparoscopic stapling device. Nine left kidneys with a single artery (6, 7, 9, 10, 11, 12, 13, 14, and 16 mm in length) and five right kidneys with a single artery (5, 13, 15, 20, and 26 mm) on imaging resulted in multiple renal arteries at implantation. Complex renal vein anatomy was associated with multiple arteries following retrieval. CONCLUSION: A main renal artery length of more than 16 mm on the left and 26 mm on the right is unlikely to result in multiple arteries to implant. The possibility of multiple arteries should be borne in mind when the donor renal artery is short.

The UK Pancreas Allocation Scheme for Whole Organ and Islet Transplantation.

In order to develop a national allocation scheme for donor pancreases, factors affecting waiting time and transplant outcomes in the United States (US) and United Kingdom (UK) were analyzed and compared. Blood group, sensitization, dialysis requirement, and whether the patient was waiting for a kidney and pancreas or pancreas alone affected waiting time in both countries; ethnicity and body mass index (BMI) also affected waiting time in the US. Ninety-day pancreas survival was similar in the UK and US, and was poorer for patients receiving a pancreas alone, with older donors, higher BMI and longer duration of ischemia in both countries. Factors affecting outcome, together with published data on factors affecting islet transplantation, informed the development of a points based allocation scheme for deceased donor pancreases in the UK providing equitable access for both whole organ and islet recipients through a single waiting list. Analysis of the allocation scheme 3 years after its introduction in December 2010 showed that the results were broadly as simulated, with a significant reduction in the number of long waiting patients and an increase in the number of islet transplants. There remains a surplus of highly sensitized patients in the waiting list, which the scheme should address in time.

Transfer of HLA-Specific Allosensitization From a Highly Sensitized Deceased Organ Donor to the Recipients of Each Kidney.

We report for the first time the adoptive transfer of donor HLA-specific allosensitization in two recipients following kidney transplantation from a highly sensitized donor. Kidneys from a donation after circulatory death donor were transplanted into two nontransfused, HLA-specific antibody negative males receiving their first transplant. Antibody screening 7 days after transplant showed high level de novo IgG HLA class I- and class II-specific antibodies in both recipients, with largely overlapping antibody profiles but no antibodies to donor HLA. The unusually rapid appearance of de novo alloantibodies in immunosuppressed nonsensitized recipients and absence of donor HLA-specific antibody prompted testing of stored donor serum that revealed high antibody levels with specificities very similar to those seen in both recipients, but in addition the presence of strong antibodies to each recipient HLA. Alloantibody levels gradually declined but were still detectable at 3 months. These findings suggest that alloreactive passenger B cells/plasma cells within the kidneys of highly sensitized donors may give rise to rapid development of posttransplant de novo HLA-specific alloantibodies. While the clinical significance of this phenomenon is uncertain it provides one explanation for the appearance of de novo HLA-specific antibodies directed against third party but not donor HLA.

Anatomical variation and its management in transplantation.

Variant anatomy may be challenging at retrieval, with failure to identify variance being associated with organ damage, particularly vascular damage. On implantation, some variants demand nonstandard techniques of reconstruction or implantation. This review covers the common and less common anatomical variants of the liver, kidney and pancreas, and gives guidance as to how they may be managed during organ retrieval and implantation.

Early graft loss after kidney transplantation: risk factors and consequences.

Early graft loss (EGL) after kidney transplantation is a catastrophic outcome that is assumed to be more likely after the use of kidneys from suboptimal donors. We therefore examined its incidence, risk factors and consequences in our center in relation to different donor types. Of 801 recipients who received a kidney-only transplant from deceased donors, 50 (6.2%) suffered EGL within 30 days of transplantation. Significant risks factors for EGL were donation after circulatory death (DCD) (odds ratio [OR] 2.88; p = 0.006), expanded criteria donor (ECD) transplantation (OR 4.22; p = 0.010), donor age (OR 1.03; p = 0.044) and recipient past history of thrombosis (OR 4.91; p = 0.001). Recipients with EGL had 12.28 times increased risk of death within the first year, but long-term survival was worse for patients remaining on the waiting list. In comparison with patients on the waiting list but not transplanted, and with all patients on the waiting list, the risk of death after EGL decreased to baseline 4 and 23 months after transplantation, respectively. Our findings suggest that DCD and ECD transplantation are significant risk factors for EGL, which is a major risk factor for recipient death. However, long-term mortality is even greater for those remaining on the waiting list.

The effect of dietary crude protein and phosphorus on grass-fed dairy cow production, nutrient status, and milk heat stability.

Dietary crude protein (CP) and phosphorus (P) have the potential to alter dairy cow production, nutrient status, and milk heat stability, specifically in early lactation. This study examined the effect of supplementary concentrates with different CP and P concentrations on blood N and P status and on milk yield, composition, and heat stability. The concentrates [4kg of dry matter (DM) concentrate per cow daily] were fed to grazing dairy cows (13kg DM grass) during early lactation. Forty-eight spring-calving dairy cows were allocated to 4 treatments: high CP, high P (HPrHP; 302g/kg DM CP, 6.8g/kg DM P), medium CP, high P (MPrHP; 202g/kg DM CP, 4.7g/kg DM P), low CP, high P (LPrHP; 101g/kg DM CP, 5.1g/kg DM P), and low CP, low P (LPrLP; 101g/kg DM CP, 0.058g/kg DM P), for 8wk. Levels of N excretion were significantly higher in animals fed the HPrHP and MPrHP concentrates; P excretion was significantly lower in animals fed the LPrLP concentrate. Reducing the level of P in the diet (LPrLP concentrate) resulted in a significantly lower blood P concentration, whereas milk yield and composition (fat and protein) were not affected by either CP or P in the diet. The effect of the interaction between treatment and time on milk urea N was significant, reflecting the positive correlation between dietary CP and milk nonprotein N. Increasing supplementary CP and P (HPrHP) in the diet resulted in significantly lower milk heat stability at pH 6.8. The findings show that increasing dietary CP caused a decrease in milk heat stability, which reduced the suitability of milk for processing. The study also found that increasing dietary CP increased milk urea N and milk nonprotein N. Increasing dietary P increased fecal P excretion. These are important considerations for milk processors and producers for control of milk processing and environmental parameters.