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Technische Briefing Kringlooplandbouw; Notitie opgesteld op verzoek van de Tweede Kamer Commissie LNV : Wat mogen we verwachten van een circulaire voedselproductie gebaseerd op een kringlooplandbouw, in het perspectief van klimaat- en biodiversiteitdoelen?
Scholten, M.C.T. ; Bianchi, F.J.J.A. ; Boer, I.J.M. de; Conijn, J.G. ; Dijkstra, J. ; Doorn, A.M. van; Ende, J.E. van den; Fresco, L.O. ; Jongschaap, R.E.E. ; Kernebeek, H.R.J. van; Lesschen, J.P. ; Olde, E.M. de; Schulte, Rogier ; Termeer, C.J.A.M. ; Vorst, J.G.A.J. van der; Vos, J.A. de; Woltjer, G.B. - \ 2018
Wageningen University and Research - 14 p.
Prediction of enteric methane production, yield, and intensity in dairy cattle using an intercontinental database
Niu, Mutian ; Kebreab, Ermias ; Hristov, Alexander N. ; Oh, Joonpyo ; Arndt, Claudia ; Bannink, André ; Bayat, Ali R. ; Brito, André F. ; Boland, Tommy ; Casper, David ; Crompton, Les A. ; Dijkstra, Jan ; Eugène, Maguy A. ; Garnsworthy, Phil C. ; Haque, Md Najmul ; Hellwing, Anne L.F. ; Huhtanen, Pekka ; Kreuzer, Michael ; Kuhla, Bjoern ; Lund, Peter ; Madsen, Jørgen ; Martin, Cécile ; Mcclelland, Shelby C. ; Mcgee, Mark ; Moate, Peter J. ; Muetzel, Stefan ; Muñoz, Camila ; O'Kiely, Padraig ; Peiren, Nico ; Reynolds, Christopher K. ; Schwarm, Angela ; Shingfield, Kevin J. ; Storlien, Tonje M. ; Weisbjerg, Martin R. ; Yáñez-Ruiz, David R. ; Yu, Zhongtang - \ 2018
Global Change Biology (2018). - ISSN 1354-1013 - p. 3368 - 3389.
Dairy cows - Dry matter intake - Enteric methane emissions - Methane intensity - Methane yield - Prediction models
Enteric methane (CH4) production from cattle contributes to global greenhouse gas emissions. Measurement of enteric CH4 is complex, expensive, and impractical at large scales; therefore, models are commonly used to predict CH4 production. However, building robust prediction models requires extensive data from animals under different management systems worldwide. The objectives of this study were to (1) collate a global database of enteric CH4 production from individual lactating dairy cattle; (2) determine the availability of key variables for predicting enteric CH4 production (g/day per cow), yield [g/kg dry matter intake (DMI)], and intensity (g/kg energy corrected milk) and their respective relationships; (3) develop intercontinental and regional models and cross-validate their performance; and (4) assess the trade-off between availability of on-farm inputs and CH4 prediction accuracy. The intercontinental database covered Europe (EU), the United States (US), and Australia (AU). A sequential approach was taken by incrementally adding key variables to develop models with increasing complexity. Methane emissions were predicted by fitting linear mixed models. Within model categories, an intercontinental model with the most available independent variables performed best with root mean square prediction error (RMSPE) as a percentage of mean observed value of 16.6%, 14.7%, and 19.8% for intercontinental, EU, and United States regions, respectively. Less complex models requiring only DMI had predictive ability comparable to complex models. Enteric CH4 production, yield, and intensity prediction models developed on an intercontinental basis had similar performance across regions, however, intercepts and slopes were different with implications for prediction. Revised CH4 emission conversion factors for specific regions are required to improve CH4 production estimates in national inventories. In conclusion, information on DMI is required for good prediction, and other factors such as dietary neutral detergent fiber (NDF) concentration, improve the prediction. For enteric CH4 yield and intensity prediction, information on milk yield and composition is required for better estimation.
Dynamics of volatile fatty acids, hydrogen, and methane in dairy cattle: A model of rumen metabolic pathways
Lingen, H.J. van; Fadel, J.G. ; Moraes, L.E. ; Kebreab, Ermias ; Bannink, A. ; Dijkstra, J. - \ 2018
On the stability and finite-size effects of a columnar phase in single-component systems of hard-rod-like particles
Dussi, Simone ; Chiappini, Massimiliano ; Dijkstra, Marjolein - \ 2018
Molecular Physics (2018). - ISSN 0026-8976 - 14 p.
columnar phase - entropy - hard particles - Liquid crystals - Monte Carlo simulations

Colloidal rod-like particles self-assemble into a variety of liquid crystal phases. In contrast to the formation of the nematic and smectic phases for which it is well understood that it can be driven by entropy, the stabilisation mechanism of a prolate columnar phase ((Formula presented.)), observed for example in fd-virus suspensions, is still unclear. Here, we investigate whether or not a (Formula presented.) phase can exist in a purely entropy-driven single-component system. We perform computer simulations of hard particles with different shapes: spherocylinders, top-shaped rods, cuboidal particles, and crooked rods. We show that the (Formula presented.) phases observed in previous simulation studies are mere artefacts due to either finite-size effects or simulation boxes that are incommensurate with the stable thermodynamic phase. In particular, we observe that the characteristic layering of the stable smectic or crystal phase disappears when the dimension of the simulation box along the direction of the layers is too small. Such a system-size effect depends both on particle shape and the competing phases, and appears to be more pronounced for less anisotropic particles.

Letter to the Editor: Recovery test results as a prerequisite for publication of gaseous exchange measurements
Gerrits, W.J.J. ; Labussiere, Etienne ; Reynolds, Chris ; Metges, Cornelia ; Kuhla, Björn ; Lund, Peter ; Weisbjerg, Martin Riis ; Dijkstra, J. - \ 2018
Journal of Dairy Science 101 (2018)6. - ISSN 0022-0302 - p. 4703 - 4704.
In the last decade, various applications of gaseous exchange measurements have been developed to quantify the production or consumption of particular gases by animals. Notably, booming research into methane emissions has led to an expansion of the number of facilities in which such measurements are made. Results of a ring test calibration of respiration chambers in the UK by Gardiner et al. (2015) confirmed our concern that not all research groups comply with the same standards of chamber operation.
Hard Competition : Stabilizing the Elusive Biaxial Nematic Phase in Suspensions of Colloidal Particles with Extreme Lengths
Dussi, Simone ; Tasios, Nikos ; Drwenski, Tara ; Roij, René Van; Dijkstra, Marjolein - \ 2018
Physical Review Letters 120 (2018)17. - ISSN 0031-9007

We use computer simulations to study the existence and stability of a biaxial nematic Nb phase in systems of hard polyhedral cuboids, triangular prisms, and rhombic platelets, characterized by a long (L), medium (M), and short (S) particle axis. For all three shape families, we find stable Nb states provided the shape is not only close to the so-called dual shape with M=LS but also sufficiently anisotropic with L/S>9,11,14,23 for rhombi, (two types of) triangular prisms, and cuboids, respectively, corresponding to anisotropies not considered before. Surprisingly, a direct isotropic-Nb transition does not occur in these systems due to a destabilization of Nb by a smectic (for cuboids and prisms) or a columnar (for platelets) phase at small L/S or by an intervening uniaxial nematic phase at large L/S. Our results are confirmed by a density functional theory provided the third virial coefficient is included and a continuous rather than a discrete (Zwanzig) set of particle orientations is taken into account.

Atmosphere-vegetation-soil interactions in a climate change context; Impact of changing conditions on engineered transport infrastructure slopes in Europe
Tang, A.M. ; Hughes, P.N. ; Dijkstra, T.A. ; Askarinejad, A. ; Brenčič, M. ; Cui, Y.J. ; Diez, J.J. ; Firgi, T. ; Gajewska, B. ; Gentile, F. ; Grossi, G. ; Jommi, C. ; Kehagia, F. ; Koda, E. ; Maat, H.W. Ter; Lenart, S. ; Lourenco, S. ; Oliveira, M. ; Osinski, P. ; Springman, S.M. ; Stirling, R. ; Toll, D.G. ; Beek, V. Van - \ 2018
Quarterly Journal of Engineering Geology and Hydrogeology 51 (2018)2. - ISSN 1470-9236 - p. 156 - 168.

In assessing the impact of climate change on infrastructure, it is essential to consider the interactions between the atmosphere, vegetation and the near-surface soil. This paper presents an overview of these processes, focusing on recent advances from the literature and those made by members of COST Action TU1202 - Impacts of climate change on engineered slopes for infrastructure. Climate- and vegetation-driven processes (suction generation, erosion, desiccation cracking, freeze- thaw effects) are expected to change in incidence and severity, which will affect the stability of new and existing infrastructure slopes. This paper identifies the climate- and vegetation-driven processes that are of greatest concern, the suite of known unknowns that require further research, and lists key aspect that should be considered for the design of engineered transport infrastructure slopes in the context of climate change.

Gluren naar vetzuren
Dijkstra, Jan - \ 2018
Site-specific aftercare completion criteria for sustainable landfilling in the Netherlands : Geochemical modelling and sensitivity analysis
Dijkstra, Joris J. ; Zomeren, André van; Brand, Ellen ; Comans, Rob N.J. - \ 2018
Waste Management 75 (2018). - ISSN 0956-053X - p. 407 - 414.
Aftercare completion - Environmental protection criteria - Geochemical modelling - Risk assessment - Sensitivity analysis - Sustainable landfill management
A novel, regulatory accepted approach is developed that enables competent authorities to decide whether landfill aftercare can be reduced or terminated. Our previous paper (Brand et al., Waste Management 2016, 56, 255–261, outlines the general approach, that consists of a 10-year treatment phase (e.g., aeration, leachate recirculation), in combination with site-specific Environmental Protection Criteria (EPC) for contaminant concentrations in the landfill leachate after treatment. The current paper presents the unique modelling approach by which the site-specific EPC are derived. The modelling approach is based on the use of mechanistic multi-surface geochemical models covering the main sorption processes in soils underneath the landfills, and is composed of widely-accepted surface complexation models in combination with published “generic” parameter sets. This approach enables the consideration of the main site-specific soil properties that influence the attenuation of emitted contaminants. In addition, the sensitivity of the EPC is shown for variation of the main physicochemical-assumptions and policy-based decisions. Site-specific soil properties have been found to substantially determine the EPC and include soil-pH, dissolved organic matter, and iron-(hydr)oxide content. Apart from the sorption capacity of the local soil, EPC also depend strongly on the assumed dilution with local groundwater in the saturated zone. An important policy-related decision that influences the calculated EPC is the assessment period during which the groundwater is protected. The transparent setup of the approach using geochemical modelling, the explicit consideration of site-specific properties and the achieved regulatory acceptance may also stimulate application to landfills in other countries.
Effects of rumen-undegradable protein on intake, performance, and mammary gland development in prepubertal and pubertal dairy heifers
Silva, A.L. ; Detmann, E. ; Dijkstra, J. ; Pedroso, A.M. ; Silva, L.H.P. ; Machado, A.F. ; Sousa, F.C. ; Santos, G.B. dos; Marcondes, M.I. - \ 2018
Journal of Dairy Science 101 (2018)7. - ISSN 0022-0302 - p. 5991 - 6001.
growth - mammary gland ultrasound - nitrogen retention
The objective of this study was to evaluate the influence of different amounts of rumen-undegradable protein (RUP) on intake, N balance, performance, mammary gland development, carcass traits, and hormonal status of Holstein heifers at different physiological stages (PS). Sixteen prepubertal (PRE) heifers (initial BW = 106 ± 7.6 kg; age = 4.3 ± 0.46 mo) and 16 pubertal (PUB) heifers (initial BW = 224 ± 7.9 kg; age = 12.6 ± 0.45 mo) were used in an experiment over a period of 84 d. Four diets with increasing RUP contents (38, 44, 51, and 57% of dietary crude protein) and heifers at 2 PS (PRE or PUB) were used in a 4 × 2 factorial arrangement of treatments in a completely randomized design. Throughout the experiment, 2 digestibility trials were performed over 5 consecutive days (starting at d 36 and 78) involving feed and ort sampling and spot collections of feces and urine. At d 0 and 83, body ultrasound images were obtained for real-time carcass trait evaluation. The mammary gland was ultrasonically scanned at d 0 and every 3 wk during the experiment. Blood samples were taken at d 0 and 84 to determine serum concentrations of progesterone, estrogen, insulin-like growth factor I (IGF-I), and insulin. No interaction between PS and the level of RUP was found for any trait. Apparent digestibility of dry matter, organic matter, and neutral detergent fiber corrected for ash and protein was not affected by RUP level but was lower for PRE compared with PUB heifers. Sorting against neutral detergent fiber corrected for ash and protein (tendency only) and for crude protein was greater for PUB than PRE heifers. Pubertal heifers had greater average daily gain (905 vs. 505 g/d) and N retention (25.9 vs. 12.5 g/d) than PRE heifers. In addition, average daily gain and N retention were greatest at 51% RUP of dietary protein. Mammary ultrasonography indicated no effects of RUP amounts on mammary gland composition, whereas PRE heifers had greater pixel values than PUB, indicating higher contents of fat rather than protein in the mammary glands of PRE heifers. Serum progesterone and IGF-I concentration was affected only by PS, and PRE heifers had greater values of progesterone and IGF-I concentrations than PUB heifers. Serum insulin concentration was unaffected by PS but tended to be higher at 51% of RUP. In conclusion, an RUP level of 51% increases body weight, average daily gain, feed efficiency, and N retention in heifers regardless of the PS. In addition, PRE heifers have a lower sorting ability and reduced intake, total-tract digestibility, and N retention. They also have higher amounts of fat in their mammary glands, even at moderate growth rates.
Short communication: The effect of linseed oil and DGAT1 K232A polymorphism on the methane emission prediction potential of milk fatty acids
Gastelen, S. van; Antunes-Fernandes, E.C. ; Hettinga, K.A. ; Dijkstra, J. - \ 2018
Journal of Dairy Science 101 (2018)6. - ISSN 0022-0302 - p. 5599 - 5604.
DGAT1 K232 polymorphism - enteric methane production - linseed oil - milk fatty acid
Several in vivo CH4 measurement techniques have been developed but are not suitable for precise and accurate large-scale measurements; hence, proxies for CH4 emissions in dairy cattle have been proposed, including the milk fatty acid (MFA) profile. The aim of the present study was to determine whether recently developed MFA-based prediction equations for CH4 emission are applicable to dairy cows with different diacylglycerol o-acyltransferase 1 (DGAT1) K232A polymorphism and fed diets with and without linseed oil. Data from a crossover design experiment were used, encompassing 2 dietary treatments (i.e., a control diet and a linseed oil diet, with a difference in dietary fat content of 22 g/kg of dry matter) and 24 lactating Holstein-Friesian cows (i.e., 12 cows with DGAT1 KK genotype and 12 cows with DGAT1 AA genotype). Enteric CH4 production was measured in climate respiration chambers and the MFA profile was analyzed using gas chromatography. Observed CH4 emissions were compared with CH4 emissions predicted by previously developed MFA-based CH4 prediction equations. The results indicate that different types of diets (i.e., with or without linseed oil), but not the DGAT1 K232A polymorphism, affect the ability of previously derived prediction equations to predict CH4 emission. However, the concordance correlation coefficient was smaller than or equal to 0.30 for both dietary treatments separately, both DGAT1 genotypes separately, and the complete data set. We therefore concluded that previously derived MFA-based CH4 prediction equations can neither accurately nor precisely predict CH4 emissions of dairy cows managed under strategies differing from those under which the original prediction equations were developed.
Predicting enteric methane emission of dairy cows with milk Fourier-transform infrared spectra and gas chromatography–based milk fatty acid profiles
Gastelen, S. van; Mollenhorst, H. ; Antunes-Fernandes, E.C. ; Hettinga, K.A. ; Burgsteden, G.G. van; Dijkstra, J. ; Rademaker, J.L.W. - \ 2018
Journal of Dairy Science 101 (2018)6. - ISSN 0022-0302 - p. 5582 - 5598.
dairy cow - enteric methane production - milk fatty acid concentration - milk Fourier-transform infrared spectroscopy

The objective of the present study was to compare the prediction potential of milk Fourier-transform infrared spectroscopy (FTIR) for CH4 emissions of dairy cows with that of gas chromatography (GC)–based milk fatty acids (MFA). Data from 9 experiments with lactating Holstein-Friesian cows, with a total of 30 dietary treatments and 218 observations, were used. Methane emissions were measured for 3 consecutive days in climate respiration chambers and expressed as production (g/d), yield (g/kg of dry matter intake; DMI), and intensity (g/kg of fat- and protein-corrected milk; FPCM). Dry matter intake was 16.3 ± 2.18 kg/d (mean ± standard deviation), FPCM yield was 25.9 ± 5.06 kg/d, CH4 production was 366 ± 53.9 g/d, CH4 yield was 22.5 ± 2.10 g/kg of DMI, and CH4 intensity was 14.4 ± 2.58 g/kg of FPCM. Milk was sampled during the same days and analyzed by GC and by FTIR. Multivariate GC-determined MFA–based and FTIR-based CH4 prediction models were developed, and subsequently, the final CH4 prediction models were evaluated with root mean squared error of prediction and concordance correlation coefficient analysis. Further, we performed a random 10-fold cross validation to calculate the performance parameters of the models (e.g., the coefficient of determination of cross validation). The final GC-determined MFA–based CH4 prediction models estimate CH4 production, yield, and intensity with a root mean squared error of prediction of 35.7 g/d, 1.6 g/kg of DMI, and 1.6 g/kg of FPCM and with a concordance correlation coefficient of 0.72, 0.59, and 0.77, respectively. The final FTIR-based CH4 prediction models estimate CH4 production, yield, and intensity with a root mean squared error of prediction of 43.2 g/d, 1.9 g/kg of DMI, and 1.7 g/kg of FPCM and with a concordance correlation coefficient of 0.52, 0.40, and 0.72, respectively. The GC-determined MFA–based prediction models described a greater part of the observed variation in CH4 emission than did the FTIR-based models. The cross validation results indicate that all CH4 prediction models (both GC-determined MFA–based and FTIR-based models) are robust; the difference between the coefficient of determination and the coefficient of determination of cross validation ranged from 0.01 to 0.07. The results indicate that GC-determined MFA have a greater potential than FTIR spectra to estimate CH4 production, yield, and intensity. Both techniques hold potential but may not yet be ready to predict CH4 emission of dairy cows in practice. Additional CH4 measurements are needed to improve the accuracy and robustness of GC-determined MFA and FTIR spectra for CH4 prediction.

Controls on the onset and termination of past hypoxia in the Baltic Sea
Papadomanolaki, Nina M. ; Dijkstra, Nikki ; Helmond, Niels A.G.M. Van; Hagens, Mathilde ; Bauersachs, Thorsten ; Kotthoff, Ulrich ; Sangiorgi, Francesca ; Slomp, Caroline P. - \ 2018
Palaeogeography Palaeoclimatology Palaeoecology 490 (2018). - ISSN 0031-0182 - p. 347 - 354.
The Baltic Sea is currently the largest marine hypoxic (O2 < 2 mg L− 1) ‘dead zone’ following excessive nutrient input from anthropogenic activities over the past century. Widespread hypoxia has previously developed in the Baltic Sea during the Holocene Thermal Maximum (HTM; 8–4 ka before present; BP) and the Medieval Climate Anomaly (MCA; 1.4–0.7 ka BP). Here we study the mechanisms that contributed to the onset and termination of this past hypoxia using geochemical and marine palynological data from a sediment record retrieved from the Landsort Deep during IODP Expedition 347 (Site M0063). Dinoflagellate cyst records and TEX86L-based sea surface temperature reconstructions indicate a major increase in salinity and temperature prior to and across the onset of the HTM hypoxic interval, underlining the importance of both temperature and salinity stratification in providing conditions conducive to the onset of hypoxia. Both salinity and temperature decline during the termination of the HTM hypoxic interval. In contrast, we find no evidence for significant changes in surface salinity during the MCA hypoxic interval and both the onset and termination of hypoxia appear to have been primarily driven by changes in temperature. Our results indicate that temperature and salinity changes were key drivers of past hypoxia in the Baltic Sea and imply that ongoing climate change will delay recovery from the modern, nutrient-driven hypoxic event in the Baltic Sea.
Post-depositional formation of vivianite-type minerals alters sediment phosphorus records
DIjkstra, Nikki ; Hagens, Mathilde ; Egger, Matthias ; Slomp, Caroline P. - \ 2018
Biogeosciences 15 (2018)3. - ISSN 1726-4170 - p. 861 - 883.
Phosphorus (P) concentrations in sediments are frequently used to reconstruct past environmental conditions in freshwater and marine systems, with high values thought to be indicative of a high biological productivity. Recent studies suggest that the post-depositional formation of vivianite, an iron(II)-phosphate mineral, might significantly alter trends in P with sediment depth. To assess its importance, we investigate a sediment record from the Bornholm Basin that was retrieved during the Integrated Ocean Drilling Program (IODP) Baltic Sea Paleoenvironment Expedition 347 in 2013, consisting of lake sediments overlain by brackish-marine deposits. Combining bulk sediment geochemistry with microanalysis using scanning electron microscope energy dispersive spectroscopy (SEM-EDS) and synchrotron-based X-ray absorption spectroscopy (XAS), we demonstrate that vivianite-type minerals rich in manganese and magnesium are present in the lake deposits just below the transition to the brackish-marine sediments (at 11.5 to 12 m sediment depth). In this depth interval, phosphate that diffuses down from the organic-rich, brackish-marine sediments meets porewaters rich in dissolved iron in the lake sediments, resulting in the precipitation of iron(II) phosphate. Results from a reactive transport model suggest that the peak in iron(II) phosphate originally occurred at the lake-marine transition (9 to 10 m) and moved downwards due to changes in the depth of a sulfidization front. However, its current position relative to the lake-marine transition is stable as the vivianite-type minerals and active sulfidization fronts have been spatially separated over time. Experiments in which vivianite was subjected to sulfidic conditions demonstrate that incorporation of manganese or magnesium in vivianite does not affect its susceptibility to sulfide-induced dissolution. Our work highlights that post-depositional formation of iron(II) phosphates such as vivianite has the potential to strongly alter sedimentary P records particularly in systems that are subject to environmental perturbation, such as a change in primary productivity, which can be associated with a lake-marine transition.
Udder health of dairy cows fed different dietary energy levels after a short or no dry period without use of dry cow antibiotics
Hoeij, R.J. van; Lam, T.J.G.M. ; Bruckmaier, R.M. ; Dijkstra, J. ; Remmelink, G.J. ; Kemp, B. ; Knegsel, A.T.M. van - \ 2018
Journal of Dairy Science 101 (2018)5. - ISSN 0022-0302 - p. 4570 - 4585.
continuous milking - decision making - antibiotic use
Reports on the effects of length of dry period (DP) on udder health of cows that were not treated with dry cow antibiotics are scarce. Additionally, the effects of a reduced dietary energy level for cows with a 0-d DP on udder health have not yet been studied. The aims of this study were (1) to compare effects of a 0-d or 30-d DP without use of dry cow antibiotics on udder health across the DP and subsequent lactation in dairy cows fed different dietary energy levels and (2) to evaluate associations between udder health and metabolic status of dairy cows. Five weeks before the expected calving date, Holstein-Friesian dairy cows (n = 115) were blocked for parity, expected calving date, and milk yield and SCC at their 2 last test days and were randomly assigned to 2 DP lengths: 0-d DP (n = 77) or 30-d DP (n = 38). Quarter milk samples were taken in wk 5 prepartum and in wk 1 and 5 postpartum. Proportion of quarters with elevated somatic cell count (SCC; SCC ≥200,000 cells/mL) and proportion of udder pathogens in quarter milk samples did not differ between DP lengths among weeks. After calving, 102 of these cows were randomly assigned to 3 treatments: a 30-d DP with a standard energy level required for expected milk yield (30-d DP SEL; n = 36), a 0-d DP with the same energy level as cows with a 30-d DP (0-d DP SEL; n = 33), and a 0-d DP with a low energy level (0-d DP LEL, n = 33). From wk 8 of lactation onward, cows received either a glucogenic ration consisting of corn silage and grass silage or a lipogenic ration consisting of grass silage and sugar beet pulp at a standard or low energy level. During wk 1 to 7 postpartum, treatment did not affect SCC or SCC corrected for milk yield. During wk 8 to 44 of lactation, 0-d DP SEL cows had a greater SCC than 0-d DP LEL or 30-d DP SEL cows and had a greater SCC corrected for milk yield than 0-d DP LEL cows. During wk 1 to 44 of lactation, occurrence of at least 1 elevation of SCC (SCC ≥200,000 cells/mL after 2 wk of SCC <200,000 cells/mL) was not different among treatments. The 0-d DP SEL cows but not the 0-d DP LEL cows tended to have a 2.17 times greater hazard of having a case of clinical mastitis at any time in lactation than 30-d DP SEL cows. In wk 1 to 44 of lactation, lower fat- and protein- corrected milk yield and energy intake, greater energy balance, and greater plasma insulin concentration were associated with greater SCC. In conclusion, DP length did not affect udder health in the DP and in early lactation but seemed to decrease udder health for 0-d DP SEL cows in later lactation compared with 30-d DP SEL or 0-d DP LEL cows.
An isotope dilution model for partitioning of phenylalanine and tyrosine uptake by the liver of lactating dairy cows
Crompton, L.A. ; Mcknight, L.L. ; Reynolds, Chris ; Mills, J.A.N. ; Ellis, J.L. ; Hanigan, M.D. ; Dijkstra, J. ; Bequette, B.J. ; Bannink, A. ; France, J. - \ 2018
Journal of Theoretical Biology 444 (2018). - ISSN 0022-5193 - p. 100 - 107.
Isotope dilution - Kinetic model - Liver - phenylalanine - Tyrosine
An isotope dilution model to describe the partitioning of phenylalanine (PHE) and tyrosine (TYR) in the bovine liver was developed. The model comprises four intracellular and six extracellular pools and various flows connecting these pools and external blood. Conservation of mass principles were applied to generate the fundamental equations describing the behaviour of the system in the steady state. The model was applied to datasets from multi-catheterised dairy cattle during a constant infusion of [1-13C] phenylalanine and [2,3,5,6-2H] tyrosine tracers. Model solutions described the extraction of PHE and TYR from the liver via the portal vein and hepatic artery. In addition, the exchange of free PHE and TYR between extracellular and intracellular pools was explained and the hydroxylation of PHE to TYR was estimated. The model was effective in providing information about the fates of PHE and TYR in the liver and could be used as part of a more complex system describing amino acid metabolism in the whole animal.
The relationship between milk metabolome and methane emission of Holstein Friesian dairy cows: Metabolic interpretation and prediction potential
Gastelen, S. van; Antunes Fernandes, E.C. ; Hettinga, K.A. ; Dijkstra, J. - \ 2018
Journal of Dairy Science 101 (2018)3. - ISSN 0022-0302 - p. 2110 - 2126.
dairy cow - enteric methane production - Milk metabolome
This study aimed to quantify the relationship between CH4 emission and fatty acids, volatile metabolites, and nonvolatile metabolites in milk of dairy cows fed forage-based diets. Data from 6 studies were used, including 27 dietary treatments and 123 individual observations from lactating Holstein-Friesian cows. These dietary treatments covered a large range of forage-based diets, with different qualities and proportions of grass silage and corn silage. Methane emission was measured in climate respiration chambers and expressed as production (g per day), yield (g per kg of dry matter intake; DMI), and intensity (g per kg of fat- and protein-corrected milk; FPCM). Milk samples were analyzed for fatty acids by gas chromatography, for volatile metabolites by gas chromatography-mass spectrometry, and for nonvolatile metabolites by nuclear magnetic resonance. Dry matter intake was 15.9 ± 1.90 kg/d (mean ± SD), FPCM yield was 25.2 ± 4.57 kg/d, CH4 production was 359 ± 51.1 g/d, CH4 yield was 22.6 ± 2.31 g/kg of DMI, and CH4 intensity was 14.5 ± 2.59 g/kg of FPCM. The results show that changes in individual milk metabolite concentrations can be related to the ruminal CH4 production pathways. Several of these relationships were diet driven, whereas some were partly dependent on FPCM yield. Next, prediction models were developed and subsequently evaluated based on root mean square error of prediction (RMSEP), concordance correlation coefficient (CCC) analysis, and random 10-fold cross-validation. The best models with milk fatty acids (in g/100 g of fatty acids; MFA) alone predicted CH4 production, yield, and intensity with a RMSEP of 34 g/d, 2.0 g/kg of DMI, and 1.7 g/kg of FPCM, and with a CCC of 0.67, 0.44, and 0.75, respectively. The CH4 prediction potential of both volatile metabolites alone and nonvolatile metabolites alone was low, regardless of the unit of CH4 emission, as evidenced by the low CCC values (<0.35). The best models combining the 3 types of metabolites as selection variables resulted in the inclusion of only MFA for CH4 production and CH4 yield. For CH4 intensity, MFA, volatile metabolites, and nonvolatile metabolites were included in the prediction model. This resulted in a small improvement in prediction potential (CCC of 0.80; RMSEP of 1.5 g/kg of FPCM) relative to MFA alone. These results indicate that volatile and nonvolatile metabolites in milk contain some information to increase our understanding of enteric CH4 production of dairy cows, but that it is not worthwhile to determine the volatile and nonvolatile metabolites in milk to estimate CH4 emission of dairy cows. We conclude that MFA have moderate potential to predict CH4 emission of dairy cattle fed forage-based diets, and that the models can aid in the effort to understand and mitigate CH4 emissions of dairy cows.
Feasibility of coupled empirical and dynamic modeling to assess climate change and air pollution impacts on temperate forest vegetation of the eastern United States
McDonnell, T.C. ; Reinds, G.J. ; Sullivan, T.J. ; Clark, C.M. ; Bonten, L.T.C. ; Mol-Dijkstra, J.P. ; Wamelink, G.W.W. ; Dovciak, M. - \ 2018
Environmental Pollution 234 (2018). - ISSN 0269-7491 - p. 902 - 914.
Acidification - Biodiversity - Climate change - Forest understory - Nitrogen
Changes in climate and atmospheric nitrogen (N) deposition caused pronounced changes in soil conditions and habitat suitability for many plant species over the latter half of the previous century. Such changes are expected to continue in the future with anticipated further changing air temperature and precipitation that will likely influence the effects of N deposition. To investigate the potential long-term impacts of atmospheric N deposition on hardwood forest ecosystems in the eastern United States in the context of climate change, application of the coupled biogeochemical and vegetation community model VSD+PROPS was explored at three sites in New Hampshire, Virginia, and Tennessee. This represents the first application of VSD+PROPS to forest ecosystems in the United States. Climate change and elevated (above mid-19th century) N deposition were simulated to be important factors for determining habitat suitability. Although simulation results suggested that the suitability of these forests to support the continued presence of their characteristic understory plant species might decline by the year 2100, low data availability for building vegetation response models with PROPS resulted in uncertain results at the extremes of simulated N deposition. Future PROPS model development in the United States should focus on inclusion of additional foundational data or alternate candidate predictor variables to reduce these uncertainties. Climate change and elevated N deposition were simulated to be important factors for determining habitat suitability for plants, and are expected to interact with changes in soil chemistry.
Structure and Function of Human Tyrosinase and Tyrosinase-Related Proteins
Lai, Xuelei ; Wichers, Harry J. ; Soler-Lopez, Montserrat ; Dijkstra, Bauke W. - \ 2018
Chemistry-A European Journal 24 (2018)1. - ISSN 0947-6539 - p. 47 - 55.
Albinism - Melanin - Metalloenzymes - Proteins - Tyrosinase
Melanin is the main pigment responsible for the color of human skin, hair and eye. Its biosynthesis requires three melanogenic enzymes, tyrosinase (TYR), and the tyrosinase-related proteins TYRP1 and TYRP2. The difficulty of isolating pure and homogeneous proteins from endogenous sources has hampered their study, and resulted in many contradictory findings regarding their physiological functions. In this review, we summarize recent advances on the structure and function of TYR and TYRPs by virtue of the crystal structure of human TYRP1, which is the first available structure of a mammalian melanogenic enzyme. This structure, combined with tyrosinase structures from other lower eukaryotes and mutagenesis studies of key active site residues, sheds light on the mechanism of TYR and TYRPs. Furthermore, a TYRP1-based homology model of TYR provides a high-quality platform to map and analyze albinism-related mutations, as well as the design of specific antimelanogenic compounds. Finally, we provide perspectives for future structure/function studies of TYR and TYRPs.
Recovery test results as a prerequisite for publication of gaseous exchange measurements
Gerrits, Walter ; Labussiere, Etienne ; Dijkstra, Jan ; Reynolds, Chris ; Metges, Cornelia ; Kuhla, Björn ; Lund, Peter ; Weisbjerg, Martin Riis - \ 2018
Animal 12 (2018)1. - ISSN 1751-7311 - p. 4 - 4.
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