Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Critically examining the knowledge base required to mechanistically project climate impacts: A case study of Europe's fish and shellfish
Catalán, Ignacio A. ; Auch, Dominik ; Kamermans, Pauline ; Morales-nin, Beatriz ; Angelopoulos, Natalie V. ; Reglero, Patricia ; Sandersfeld, Tina ; Peck, Myron A. - \ 2019
Fish and Fisheries (2019). - ISSN 1467-2960 - 17 p.
aquaculture - climate change - experiments - fisheries - gap analysis - meta-analysis
An amalgam of empirical data from laboratory and field studies is needed to build robust, theoretical models of climate impacts that can provide science-based advice for sustainable management of fish and shellfish resources. Using a semi-systematic literature review, Gap Analysis and multilevel meta-analysis,
we assessed the status of empirical knowledge on the direct effects of climate change on 37 high-value species targeted by European fisheries and aquaculture sectors operating in marine and freshwater regions. Knowledge on potential climate change-related drivers (single or combined) on several responses (vital rates) across four categories (exploitation sector, region, life stage, species), was considerably unbalanced as well as biased, including a low number of studies (a) examining the interaction of abiotic factors, (b) offering opportunities to assess local adaptation, (c) targeting lower-value species. The meta-analysis
revealed that projected warming would increase mean growth rates in fish
and mollusks and significantly elevate metabolic rates in fish. Decreased levels of
dissolved oxygen depressed rates of growth and metabolism across coherent species groups (e.g., small pelagics, etc.) while expected declines in pH reduced growth in most species groups and increased mortality in bivalves. The meta-analytical results were influenced by the study design and moderators (e.g., life stage, season). Although meta-analytic tools have become increasingly popular, when performed on the limited available data, these analyses cannot grasp relevant population effects, even in species with a long history of study. We recommend actions to overcome these shortcomings and improve mechanistic (cause-and-effect) projections of climate impacts on fish and shellfish.
Plant-derived polyunsaturated fatty acids and markers of glucose metabolism and insulin resistance : A meta-analysis of randomized controlled feeding trials
Wanders, Anne J. ; Blom, Wendy A.M. ; Zock, Peter L. ; Geleijnse, Johanna M. ; Brouwer, Ingeborg A. ; Alssema, Marjan - \ 2019
BMJ Open Diabetes Research and Care 7 (2019)1. - ISSN 2052-4897
dietary fat - glucose metabolism - insulin resistance - Linoleic acid - meta-analysis

The objective of this meta-analysis was to investigate the effects of plant-derived polyunsaturated fatty acids (PUFAs) on glucose metabolism and insulin resistance. Scopus and PubMed databases were searched until January 2018. Eligible studies were randomized controlled feeding trials that investigated the effects of a diet high in plant-derived PUFA as compared with saturated fatty acids (SFA) or carbohydrates and measured markers of glucose metabolism and insulin resistance as outcomes. Data from 13 relevant studies (19 comparisons of plant-derived PUFA with control) were retrieved. Plant-derived PUFA did not significantly affect fasting glucose (-0.01 mmol/L (95 % CI - 0.06 to 0.03 mmol/L)), but lowered fasting insulin by 2.6 pmol/L (-4.9 to -0.2 pmol/L) and homeostatic model assessment-insulin resistance (HOMA-IR) by 0.12 units (-0.23 to - 0.01 units). In dose-response analyses, a 5% increase in energy (En%) from PUFA significantly reduced insulin by 5.8 pmol/L (95% CI -10.2 to -1.3 pmol/L), but not glucose (change -0.07, 95% CI -0.17 to 0.04 mmol/L) and HOMA-IR (change - 0.24, 95% CI -0.56 to 0.07 units). In subgroup analyses, studies with higher PUFA dose (upper tertiles) reduced insulin (-6.7, -10.5 to -2.9 pmol/L) and HOMA-IR (-0.28, -0.45 to -0.12 units), but not glucose (-0.09, 95% CI -0.18 to 0.01 mmol/L), as compared with an isocaloric control. Subgroup analyses showed no differences in effects between SFA and carbohydrates as replacement nutrients (p interaction ≥0.05). Evidence from randomized controlled trials indicated that plant-derived PUFA as an isocaloric replacement for SFA or carbohydrates probably reduces fasting insulin and HOMA-IR in populations without diabetes.

Quantitative analysis of the dose–response of white spot syndrome virus in shrimp
Ngo, Thuy T.N. ; Senior, Alistair M. ; Culina, Antica ; Santos, Eduardo S.A. ; Vlak, Just M. ; Zwart, Mark P. - \ 2018
Journal of Fish Diseases 41 (2018)11. - ISSN 0140-7775 - p. 1733 - 1744.
dose–response - infection - meta-analysis - modelling - shrimp - white spot syndrome virus

White spot syndrome virus (WSSV) is an important cause of mortality and economic losses in shrimp farming. Although WSSV-induced mortality is virus dose dependent and WSSV infection does not necessarily lead to mortality, the relationships between virus-particle dose, infection and mortality have not been analysed quantitatively. Here, we explored WSSV dose–response by a combination of experiments, modelling and meta-analysis. We performed dose–response experiments in Penaeus vannamei postlarvae, recorded host mortality and detected WSSV infection. When we fitted infection models to these data, two models—differing in whether they incorporated heterogeneous host susceptibility to the virus or not—were supported for two independent experiments. To determine the generality of these results, we reanalysed published data sets and then performed a meta-analysis. We found that WSSV dose–response kinetics is indeed variable over experiments. We could not clearly identify which specific infection model has the most support by meta-analysis, but we argue that these results also are most concordant with a model incorporating varying levels of heterogeneous host susceptibility to WSSV. We have identified suitable models for analysing WSSV dose–response, which can elucidate the most basic virus–host interactions and help to avoid underestimating WSSV infection at low virus doses.

Crop traits drive soil carbon sequestration under organic farming
García-Palacios, Pablo ; Gattinger, Andreas ; Bracht-Jørgensen, Helene ; Brussaard, Lijbert ; Carvalho, Filipe ; Castro, Helena ; Clément, Jean Christophe ; Deyn, Gerlinde De; Hertefeldt, Tina D'; Foulquier, Arnaud ; Hedlund, Katarina ; Lavorel, Sandra ; Legay, Nicolas ; Lori, Martina ; Mäder, Paul ; Martínez-García, Laura B. ; Martins da Silva, Pedro ; Muller, Adrian ; Nascimento, Eduardo ; Reis, Filipa ; Symanczik, Sarah ; Paulo Sousa, José ; Milla, Rubén - \ 2018
Journal of Applied Ecology 55 (2018)5. - ISSN 0021-8901 - p. 2496 - 2505.
climate change mitigation - crop residue - ecological intensification - leaf nitrogen - meta-analysis - organic farming - resource economics traits - soil carbon stocks

Organic farming (OF) enhances top soil organic carbon (SOC) stocks in croplands compared with conventional farming (CF), which can contribute to sequester C. As farming system differences in the amount of C inputs to soil (e.g. fertilization and crop residues) are not enough to explain such increase, shifts in crop residue traits important for soil C losses such as litter decomposition may also play a role. To assess whether crop residue (leaf and root) traits determined SOC sequestration responses to OF, we coupled a global meta-analysis with field measurements across a European-wide network of sites. In the meta-analysis, we related crop species averages of leaf N, leaf-dry matter content, fine-root C and N, with SOC stocks and sequestration responses in OF vs. CF. Across six European sites, we measured the management-induced changes in SOC stocks and leaf litter traits after long-term ecological intensive (e.g. OF) vs. CF comparisons. Our global meta-analysis showed that the positive OF-effects on soil respiration, SOC stocks, and SOC sequestration rates were significant even in organic farms with low manure application rates. Although fertilization intensity was the main driver of OF-effects on SOC, leaf and root N concentrations also played a significant role. Across the six European sites, changes towards higher leaf litter N in CF also promoted lower SOC stocks. Our results highlight that crop species displaying traits indicative of resource-acquisitive strategies (e.g. high leaf and root N) increase the difference in SOC between OF and CF. Indeed, changes towards higher crop residue decomposability was related with decreased SOC stocks under CF across European sites. Synthesis and applications. Our study emphasizes that, with management, changes in crop residue traits contribute to the positive effects of organic farming (OF) on soil carbon sequestration. These results provide a clear message to land managers: the choice of crop species, and more importantly their functional traits (e.g. leave and root nitrogen), should be considered in addition to management practices and climate, when evaluating the potential of OF for climate change mitigation.

Relative importance of competition and plant–soil feedback, their synergy, context dependency and implications for coexistence
Lekberg, Ylva ; Bever, James D. ; Bunn, Rebecca A. ; Callaway, Ragan M. ; Hart, Miranda M. ; Kivlin, Stephanie N. ; Klironomos, John ; Larkin, Beau G. ; Maron, John L. ; Reinhart, Kurt O. ; Remke, Michael ; Putten, Wim H. van der - \ 2018
Ecology Letters 21 (2018)8. - ISSN 1461-023X - p. 1268 - 1281.
Additive interaction - coexistence - competition - facilitation - meta-analysis - mutualist - pathogen - plant–soil feedback - resource gradient - soil biota

Plants interact simultaneously with each other and with soil biota, yet the relative importance of competition vs. plant–soil feedback (PSF) on plant performance is poorly understood. Using a meta-analysis of 38 published studies and 150 plant species, we show that effects of interspecific competition (either growing plants with a competitor or singly, or comparing inter- vs. intraspecific competition) and PSF (comparing home vs. away soil, live vs. sterile soil, or control vs. fungicide-treated soil) depended on treatments but were predominantly negative, broadly comparable in magnitude, and additive or synergistic. Stronger competitors experienced more negative PSF than weaker competitors when controlling for density (inter- to intraspecific competition), suggesting that PSF could prevent competitive dominance and promote coexistence. When competition was measured against plants growing singly, the strength of competition overwhelmed PSF, indicating that the relative importance of PSF may depend not only on neighbour identity but also density. We evaluate how competition and PSFs might interact across resource gradients; PSF will likely strengthen competitive interactions in high resource environments and enhance facilitative interactions in low-resource environments. Finally, we provide a framework for filling key knowledge gaps and advancing our understanding of how these biotic interactions influence community structure.

Dataset supplementing Lichtenberg et al. (2017) A global synthesis of the effects of diversified farming systems on arthropod diversity within fields and across agricultural landscapes. Global Change Biology
Lichtenberg, Elinor M. ; Kennedy, Christina M. ; Kremen, Claire ; Batáry, Péter ; Berendse, F. ; Bommarco, Riccardo ; Bosque-Pérez, Nilsa A. ; Carvalheiro, Luísa G. ; Snyder, William E. ; Williams, Neal M. - \ 2017
agricultural management schemes - arthropod diversity - functional groups - landscape complexity - meta-analysis - evenness - biodiversity - organic farming - plant diversity
This dataset contains data and scripts that supplement the publication
Association of sleep duration and quality with blood lipids : a systematic review and meta-analysis of prospective studies
Kruisbrink, Marlot ; Robertson, Wendy ; Ji, Chen ; Miller, Michelle A. ; Geleijnse, Johanna M. ; Cappuccio, Francesco P. - \ 2017
BMJ Open 7 (2017)12. - ISSN 2044-6055
blood lipids - cholesterol - meta-analysis - sleep duration - sleep quality - systematic review

OBJECTIVES: To assess the longitudinal evidence of the relationships between sleep disturbances (of quantity and quality) and dyslipidaemia in the general population and to quantify such relationships.

SETTING: Systematic review and meta-analysis following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

METHODS: We performed a systematic search of PubMed and Embase (up to 9 September 2017), complemented with manual searches, of prospective population studies describing the association between sleep duration and quality and the incidence of dyslipidaemias. Relative risks (95% CIs) were extracted and pooled using a random effects model. Subgroup analyses by lipid type were performed. Heterogeneity and publication bias were also assessed. Quality was assessed with Downs and Black score.

PARTICIPANTS: Studies were included if they were prospective, had measured sleep quantity and/or quality at baseline and either incident cases of dyslipidaemia or changes in blood lipid fractions assessed prospectively.

PRIMARY OUTCOME MEASURES: Incidence of dyslipidaemia and changes in lipid fractions. Dyslipidaemia was defined as a high total cholesterol, triglycerides, low-density lipoprotein cholesterol or low high-density lipoprotein cholesterol compared with the reference group.

RESULTS: Thirteen studies were identified (eight using sleep duration, four sleep quality and one both). There was heterogeneity in the sleep quality aspects and types of lipids assessed. Classification of sleep duration (per hour/groups) also varied widely. In the pooled analysis of sleep duration (6 studies, 16 cohort samples; 30 033 participants; follow-up 2.6-10 years), short sleep was associated with a risk of 1.01 (95% CI 0.93 to 1.10) of developing dyslipidaemia, with moderate heterogeneity (I2=56%, P=0.003) and publication bias (P=0.035). Long sleep was associated with a risk of 0.98 (95% CI 0.87 to 1.10) for dyslipidaemia, with heterogeneity (I2=63%, P<0.001) and no significant publication bias (P=0.248).

CONCLUSION: The present analysis was unable to find supportive evidence of a significant relationship between sleep duration and the development of dyslipidaemia. However, heterogeneity and small number of studies limit the interpretation.

PROSPERO REGISTRATION NUMBER: CRD42016045242.

A meta-analysis of effects of post-hatch food and water deprivation on development, performance and welfare of chickens
Jong, I.C. de; Riel, J.W. van; Bracke, M.B.M. ; Brand, H. van den - \ 2017
PLoS ONE 12 (2017)12. - ISSN 1932-6203 - 20 p.
Chicken - Body weight - Yolk Sac - Gastrointestinal tract - animal performance - poultry - jejunum - meta-analysis
A ‘meta-analysis’ was performed to determine effects of post-hatch food and water deprivation (PHFWD) on chicken development, performance and welfare (including health). Two types of meta-analysis were performed on peer-reviewed scientific publications: a quantitative ‘meta-analysis’ (MA) and a qualitative analysis (QA). Previously reported effects of PHFWD were quantified in the MA, for variables related to performance, mortality and relative yolk sac weight. The QA counted the number of studies reporting (non-)significant effects when five or more records were available in the data set (i.e. relative heart, liver and pancreas weight; plasma T3, T4 and glucose concentrations; relative duodenum, jejunum and ileum weight; duodenum, jejunum and ileum length; and villus height and crypt depth in duodenum, jejunum and ileum). MA results indicated that 24 hours of PHFWD (i.e. ≥12–36 hours) or more resulted in significantly lower body weights compared to early-fed chickens up to six weeks of age. Body weights and food intake were more reduced as durations of PHFWD (24, 48, 72, ≥84 hours) increased. Feed conversion rate increased in chickens up to 21 and 42 days of age after ≥84 hours PHFWD in comparison with chickens fed earlier. Total mortality at day 42 was higher in chickens after 48 hours PHFWD compared to early fed chickens or chickens after 24 hours PHFWD. First week mortality was higher in chickens after ≥84 hours PHFWD than in early fed chickens. The MA for relative yolk sac weight was inconclusive for PHFWD. The QA for plasma T3, T4 and glucose concentrations indicated mainly short-term decreases in T3 and glucose in PHFWD chickens compared to early fed chickens, and no effects of PHFWD on T4 concentrations. Relative weights of liver, pancreas and heart were lower after PHFWD, but only in the first week of life. A retarded development of gut segments (duodenum, jejunum and ileum) was found in the first week of life, measured as shorter, lower relative weight, and lower villus height and crypt depth. It is concluded that 48 hours (≥36–60 hours) PHFWD leads to lower body weights and higher total mortality in chickens up to six weeks of age, the latter suggesting compromised chicken welfare, but effects of PHFWD on organ development and physiological status appear to be mainly short-term.
Changes in body composition as a result of chemotherapy : Comparing women with and without breast cancer
Berg, Maaike M.G.A. van den - \ 2017
Wageningen University. Promotor(en): Ellen Kampman; M. Visser, co-promotor(en): Renate Winkels; Jeanne de Vries. - Wageningen : Wageningen University - ISBN 9789463436984 - 140
body composition - neoplasms - cancer - drug therapy - breast cancer - body weight - intake - diet - meta-analysis - toxicity - lichaamssamenstelling - neoplasma's - geneesmiddelenbehandeling - borstkanker - lichaamsgewicht - opname (intake) - dieet - meta-analyse - toxiciteit

Because of the improved survival rate, both short term and long term adverse effects of breast cancer treatment have become increasingly important. Body weight and body composition before, during, and after chemotherapy may influence side effects during treatment and survival. The aims of this thesis were to assess among stage I-IIIB breast cancer patients: 1) the association between pre-treatment body composition and dose-limiting toxicities during chemotherapy, 2) potential changes in body weight and body composition during and after chemotherapy compared to changes in age-matched women without cancer in the same time period, and 3) dietary intake during chemotherapy compared to age-matched women without cancer in the same time period.

Chapter 2 describes the association between pre-treatment body composition and dose-limiting toxicities during chemotherapy. Data from 172 breast cancer patients who participated in the COBRA-study were analysed. Body composition was measured using a total body Dual Energy X-ray Absorption (DEXA) scan. Information regarding dose-limiting toxicities was abstracted from medical records. A higher BMI (kg/m2) and a higher fat mass (kg and percentage) were associated with an increased risk of dose-limiting toxicity, while lean body mass (kg) was not associated with risk of toxicities.

Chapter 3 presents the findings of a meta-analysis on changes in body weight during chemotherapy in breast cancer patients. The meta-analysis showed an overall gain in body weight of 2.7 kg (95% CI: 2.0-3.3) during chemotherapy, with a high degree of heterogeneity (I2= 94.2%). Weight gain in breast cancer patients was more pronounced in papers published before 2000 and studies including cyclophosphamide, methotrexate and 5-fluorouracil as chemotherapy regime.

Chapter 4 describes changes in body weight and body composition during and after chemotherapy. Data from 145 patients and 121 women of an age-matched comparison group, participating in the COBRA-study were analysed. Body composition was measured using DEXA-scan at three time points during the study period. For the patient group, these tie points were: before start of chemotherapy, shortly after chemotherapy, and 6 months after chemotherapy. For the comparison group these measurements were conducted over a similar time frame: baseline, 6 months after baseline, and 12 months after baseline. In addition, we identified determinants of changes in body weight and body composition.

Shortly after chemotherapy, patients had a significantly higher body weight, BMI, and lean body mass than women in the comparison group, while fat mass was similar. Six months after chemotherapy no differences in body weight or body composition were observed between the patient and comparison group. A younger age, better appetite during chemotherapy, and an ER-receptor negative tumour were associated with greater changes in body weight over time. A younger age and better appetite during chemotherapy were associated with greater changes in fat mass over time, while the only determinant associated with greater changes in lean body mass over time was a better appetite during chemotherapy.

Chapter 5 describes the dietary intake and food groups before and during chemotherapy of breast cancer patients compared with women without cancer. In addition we assessed the association between symptoms and energy intake. Data from 117 breast cancer patients and 88 women without breast cancer who participated in the COBRA-study were used. Habitual dietary intake before chemotherapy was assessed using a food frequency questionnaire. Two 24-hr dietary recalls were used to assess actual dietary intake during chemotherapy for patients and within 6 months for the comparison group. Shortly after the 24-hr dietary recall, participants filled out questionnaires about symptoms. Before chemotherapy, dietary intake was similar for both groups. During chemotherapy, breast cancer patients reported significantly lower total energy, total fat, total protein, and alcohol intake than women without cancer, which could be explained by a lower intake of specific food groups.

Overall results from this thesis suggest that pre-treatment fat mass is associated with dose-limiting toxicities during chemotherapy. Weight gain during chemotherapy appeared to be more modest than we expected based on literature and changes in body composition during chemotherapy consist mainly of an increase in lean body mass, which is only temporary and returned to baseline within 6 months after chemotherapy. A higher appetite during chemotherapy was associated with changes in body weight and body composition. A younger age at diagnosis was associated with greater changes in body weight and fat mass, but not with changes in lean body mass. In addition, an ER-receptor negative tumour was associated with greater changes in body weight, but not with changes in fat mass or lean body mass. During chemotherapy women with breast cancer have a lower intake of energy, fat, protein and alcohol compared to age-matched women without cancer, which was expressed in a lower intake of specific food groups. The results of this thesis do not suggest that dietary intake is associated with weight gain during chemotherapy.

On the role of soil organic matter for crop production in European arable farming
Hijbeek, Renske - \ 2017
Wageningen University. Promotor(en): Martin van Ittersum, co-promotor(en): Hein ten Berge. - Wageningen : Wageningen University - ISBN 9789463436632 - 211
soil fertility - soil fertility management - soil management - soil conservation - organic matter - soil organic matter - nitrogen - nitrogen fertilizers - green manures - manures - straw - soil carbon sequestration - cover crops - crop yield - yields - meta-analysis - food security - europe - drivers - barriers - bodemvruchtbaarheid - bodemvruchtbaarheidsbeheer - bodembeheer - bodembescherming - organische stof - organisch bodemmateriaal - stikstof - stikstofmeststoffen - groenbemesters - mest - stro - koolstofvastlegging in de bodem - dekgewassen - gewasopbrengst - opbrengsten - meta-analyse - voedselzekerheid - europa - chauffeurs - barrières

The aim of this thesis was to improve understanding of the role of organic inputs and soil organic matter (SOM) for crop production in contemporary arable farming in Europe. For this purpose, long-term experiments were analysed on the additional yield effect of organic inputs and savings in mineral fertiliser. In addition, a farm survey was conducted to find drivers and barriers for the use of organic inputs and to assess if arable farmers in Europe perceive a deficiency of SOM.

The findings in this thesis suggest that at least on the shorter term, on average, there seems to be no immediate threat from a deficiency of SOM to crop production in arable farming in Europe. The long-term experiments showed that with sufficient use of only mineral fertilisers, on average, similar yields could be attained over multiple years as with the combined use of organic inputs and mineral fertiliser. This was reflected in the farm survey, in which a large majority of farmers indicated not to perceive a deficiency of SOM. Analysis of long-term experiments also showed that more mineral fertiliser N was saved when using farmyard manure at high N rates (with mineral fertiliser application) than at low N rates (without mineral fertiliser application), based on comparisons at equal yield.

Specific crops and environments did benefit from organic inputs and more SOM in terms of crop production. Long-term experiments showed that organic inputs give benefit to crop production in wet climates and on sandy soils. In addition, farmers perceived a higher deficiency of SOM on steep slopes, sandy soils, wet and very dry climates. The additional yield effect of organic inputs was significant for potatoes. More in general, farmers who cultivated larger shares of their land with specialized crops (including potatoes, sugar beets, onions and other vegetables) than cereals perceived a higher deficiency of SOM. It seems that while the functions of SOM can be replaced with technical means to a large extent (e.g. tillage, use of mineral fertilisers), there are limits to this technical potential when environmental conditions are more extreme and crops are more demanding.

The farm survey revealed that farmers perceive a trade-off between improved soil quality on the one hand and increased pressures from weeds, pests and diseases and financial consequences on the other hand when using organic inputs. If policies aim to stimulate the maintenance or increase of SOM, more insight is needed into the conditions that regulate the pressures of weeds, pests and diseases in response to organic inputs. Financial consequences (at least on the short term) should also be accounted for. More importantly however, benefits from SOM for crop production cannot be taken for granted. Only in specific situations such benefits will exist. If European policies on SOM aim to include benefits for crop production, focus should be on areas with more extreme environmental conditions (very dry or wet climates, steep slopes, sandy soils), or cropping systems with more specialized or horticultural crops rather than cereals.

Biochar boosts tropical but not temperate crop yields
Jeffery, Simon ; Abalos Rodriguez, Diego ; Prodana, Marija ; Bastos, Ana Catarina ; Groenigen, Jan Willem van; Hungate, Bruce A. ; Verheijen, Frank - \ 2017
Environmental Research Letters 12 (2017)5. - ISSN 1748-9318
biochar - crop yield - meta-analysis - soil

Applying biochar to soil is thought to have multiple benefits, from helping mitigate climate change [1, 2], to managing waste [3] to conserving soil [4]. Biochar is also widely assumed to boost crop yield [5, 6], but there is controversy regarding the extent and cause of any yield benefit [7]. Here we use a global-scale meta-analysis to show that biochar has, on average, no effect on crop yield in temperate latitudes, yet elicits a 25% average increase in yield in the tropics. In the tropics, biochar increased yield through liming and fertilization, consistent with the low soil pH, low fertility, and low fertilizer inputs typical of arable tropical soils. We also found that, in tropical soils, high-nutrient biochar inputs stimulated yield substantially more than low-nutrient biochar, further supporting the role of nutrient fertilization in the observed yield stimulation. In contrast, arable soils in temperate regions are moderate in pH, higher in fertility, and generally receive higher fertilizer inputs, leaving little room for additional benefits from biochar. Our findings demonstrate that the yield-stimulating effects of biochar are not universal, but may especially benefit agriculture in low-nutrient, acidic soils in the tropics. Biochar management in temperate zones should focus on potential non-yield benefits such as lime and fertilizer cost savings, greenhouse gas emissions control, and other ecosystem services.

Life history of the Harlequin ladybird, Harmonia axyridis; a global meta-analysis
Raak-van den Berg, C.L. ; Hemerik, A. ; Werf, W. van der; Jong, P.W. de; Lenteren, J.C. van - \ 2017
meta-analysis - invasive populations - Harmonia axyridis - life history characteristics - temperature dependence - native area - coccinellid
Data collected en used for a meta analysis on life history data of H. axyridis. And the resulting 20 best models for each life history characteristic. Published in the paper: Life history of the Harlequin ladybird, Harmonia axyridis; a global meta-analysis.
Dietary protein, blood pressure and mortality : the value of repeated measurements
Tielemans, S.M.A.J. - \ 2016
Wageningen University. Promotor(en): Marianne Geleijnse; Daan Kromhout, co-promotor(en): Hendriek Boshuizen. - Wageningen : Wageningen University - ISBN 9789462577916 - 169 p.
cardiovascular diseases - blood pressure - dietary protein - mortality - cardiovascular disorders - hypertension - urea - meta-analysis - antihypertensive agents - plant protein - animal protein - hart- en vaatziekten - bloeddruk - voedingseiwit - mortaliteit - hart- en vaatstoornissen - hypertensie - ureum - meta-analyse - antihypertensiva - plantaardig eiwit - dierlijk eiwit

Cardiovascular diseases (CVD) are the main cause of death worldwide. In 2012, about 17.5 million people died from CVD, accounting for 30% of all deaths. High blood pressure (BP) is a major cardiovascular risk factor, which was responsible for 10.4 million deaths in 2013. Diet and lifestyle play an important role in the etiology of hypertension. Maintenance of a desirable body weight, physical activity, and low intake of alcohol and salt are well-known measures to avoid high BP. Whether dietary protein, or more specifically plant and animal protein, could contribute to maintaining a healthy BP is less clear. The association between BP and CVD mortality has been extensively investigated. BP in prospective studies can be analyzed using different approaches, such as single BP (measured at one moment in time), single BP adjusted for regression dilution, average BP, and trajectories of BP. It is not yet clear which of these approaches is to be preferred for CVD risk prediction.

This thesis is centered on BP as a major cardiovascular risk factor. In the first part (Chapter 2, 3 and 4), the relation of dietary protein intake with BP level and change was examined. In the second part (Chapter 5 and 6), various approaches for analyzing repeated BP measurements were compared in relation to CVD and all‑cause mortality risk. The final chapter discusses the main findings and their implications.

Chapter 2 describes the association of 24-h urinary urea excretion, as a biomarker of total protein intake, with 9-year incidence of hypertension. We analyzed data of ~4000 men and women aged 28–75 years, who participated in the Prevention of Renal and Vascular Endstage Disease (PREVEND) study, a prospective cohort study. BP was measured four times during 1997–2009 and participants were followed for hypertension incidence, defined as BP ≥140/90mmHg or use of antihypertensive medication. Urea excretion was assessed in two consecutive 24-h urine collections at baseline and approximately 4 years later, from which total protein intake was estimated. Protein intake based on 24-h urinary urea excretion was not associated with incident hypertension.

Chapter 3 presents findings for long-term total, animal and plant protein intake in relation to 5‑year BP change. Analyses were based on 702 observations of 272 men who participated in the Zutphen Elderly Study. Participants did not use antihypertensive medication and were initially free of CVD. Physical and dietary examinations were performed in 1985, 1990, 1995, and 2000. BP was measured twice at each examination and protein intake was assessed using the cross-check dietary history method. The upper tertiles of plant protein intake were associated with a mean 5‑year change in systolic BP of ‑2.9 mmHg (95% CI: ‑5.6, ‑0.2), compared with the bottom tertile. Total and animal protein intake was not associated with BP.

Chapter 4 describes a meta‑analysis of 12 observational studies and 17 randomized controlled trials (RCTs) of dietary protein, including animal and plant protein, in relation to BP. Protein intake in prospective cohort studies was not associated with incident hypertension. For RCTs that used carbohydrate as a control treatment, the pooled BP effect was ‑2.1 mmHg systolic (95% CI: ‑2.9, ‑1.4) for a weighted mean contrast in protein intake of 41 grams per day. There was no differential effect of animal and plant protein on BP.

Chapter 5 describes repeated BP measures and their association with CVD and all‑cause mortality and life years lost in two prospective and nearly extinct cohorts of middle-aged men, the Minnesota Business and Professional Men Study (n=261) and the Zutphen Study (n=632). BP was measured annually during 1947–1957 in Minnesota and 1960–1970 in Zutphen. After 10 years of BP measurements, men were followed until death on average 20 years later. Each 25-mmHg increase in average SBP was associated with a 49% to 72% greater CVD mortality risk, 34% to 46% greater all-cause mortality risk and 3 to 4 life years lost. Four systolic BP trajectories were identified, in which mean systolic BP increased by 5 to 49 mmHg in Minnesota and 5 to 20 mmHg in Zutphen between age 50 and 60. In Zutphen, a 2-times greater CVD and all-cause mortality risk and 4 life years lost were observed when comparing trajectories. In Minnesota, associations were twice as strong. BP trajectories were the strongest predictors of CVD mortality and life years lost in Minnesota men, whereas in Zutphen men, the average BP was superior to other measures.

Chapter 6 presents findings for average BP and BP trajectories in relation to CVD and all-cause mortality, taking into account antihypertensive medication. A total of 762 participants aged ≥50 years of the Rancho Bernardo Study were examined five times from 1984 to 2002 and monitored for cause‑specific mortality from 2002 to 2013. Each 20‑mmHg increment in average systolic BP was associated with 35% greater CVD mortality and 25% greater all-cause mortality risk. We identified four trajectories for systolic BP for which BP increases ranged from 5 to 12 mmHg between age 60 and 70. In individuals who belonged to the higher trajectories, 2‑3 times greater CVD mortality and 1.5-times greater all-cause mortality risks were observed, compared to those who belonged to the lowest trajectory. Long-term systolic BP trajectories and average systolic BP were both significant predictors of CVD and all-cause mortality. The associations were not modified by antihypertensive medication.

As described in Chapter 7, various approaches were used to study the relation between protein intake and BP. Findings from individual studies and a meta-analysis suggest that dietary protein per se does not affect BP within the range of intake generally consumed in the Netherlands. Replacing carbohydrates by protein, however, has a beneficial effect on BP.

Moreover, this thesis showed that BP trajectories are not superior to average BP in predicting CVD and all-cause mortality. A few repeated BP measurements, e.g. three or four, are likely to be sufficient for obtaining a reliable average BP and had a similar predictive value for mortality compared to BP trajectories. Therefore, average BP can be considered the most practical tool for estimating mortality risk.

Estimating requirements for apparent faecal and standardised ileal digestible amino acids in laying hens by a metaanalysis approach
Krimpen, M.M. van; Veldkamp, T. ; Riel, J.W. van; Khaksar, V. ; Hashemipour, H. ; Blok, M.C. ; Spek, W. - \ 2015
Wageningen : Wageningen UR Livestock Research (Livestock research report 848) - 71
hennen - aminozuren - voer - meta-analyse - verteerbaarheid - eiwitverteerbaarheid - dunne darm - voedingsstoffengehalte - voedingsstoffenbehoeften - voedingsbehoeften - pluimvee - pluimveevoeding - hens - amino acids - feeds - meta-analysis - digestibility - protein digestibility - small intestine - nutrient content - nutrient requirements - feed requirements - poultry - poultry feeding
The aim of the present study is to update the requirements for the essential amino acids of laying hens, both on a AFD and SID basis, by performing a meta-analysis on dose-response studies used to derive requirement values for essential amino acids (lysine, methionine+cysteine, threonine and tryptophan) in laying hens as presented in the literature. In this meta-analysis, the data are fitted by use of the Wood equation (see paragraph 2.4). The amino acid intake levels for realizing maximal rate of lay, egg mass and feed efficiency are provided. The amino acid requirements for use in practice are based on the amino acid intake levels at which 95% of these maximum responses were reached.
Meta-analysis of the effect of global warming on local species richness
Arets, E.J.M.M. ; Verwer, C.C. ; Alkemade, J.R.M. - \ 2014
Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-paper 34) - 10
klimaatverandering - soortendiversiteit - effectvoorspelling - meta-analyse - climatic change - species diversity - impact prediction - meta-analysis
We carried out a systematic review of global and regional modelling studies in which shifts in species distributions under climate change were modelled. These studies included a large range of species groups and biomes worldwide. Based on the model results we calculated the fraction of species that would remain at a locality in response to projected climate change and related this to the global mean temperature increase (GMTI) that was associated with projected climate change. Out of 207 articles meeting our search terms used in Web of Science, 21 studies met our selection criteria and were included. This resulted in 239 data points of combinations of global mean temperature increase and effect on local species richness across different species groups and biomes. Based on this we carried out a meta-analysis to investi¬gate the relation between changes in global mean tem-perature increase and the fraction of remaining plant and vertebrate species at a geographic location. The results showed that global mean temperature increases of more than 2°C above pre-industrial levels significantly affect local species richness. Both plants and vertebrate species showed a strong decline in the fraction remaining species with increasing temperature. The effect impacts seemed to be strongest in warm biomes and tended to be smaller in cool biomes. The resulting meta-model can be used to calculate the fraction of remaining species under different climate change scenarios.
Variation of milk urea in dairy cattle : a study on factors that affect the relationship between urea concentration in milk and urea excretion in urine
Spek, J.W. - \ 2013
Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): Jan Dijkstra; Andre Bannink. - S.l. : s.n. - ISBN 9789461736642 - 156
melkkoeien - melkvee - ureum - melk - concentratie - urinering - excretie - stikstof - meta-analyse - natriumchloride - opname (intake) - diervoeding - rundveevoeding - voedingsfysiologie - dairy cows - dairy cattle - urea - milk - concentration - urination - excretion - nitrogen - meta-analysis - sodium chloride - intake - animal nutrition - cattle feeding - nutrition physiology

The aim of this thesis was to increase the applicability of milk urea nitrogen concentration (MUN) as a predictor of urinary urea nitrogen excretion (UUN) by identifying and quantifying factors that can explain variation in MUN that is not related to UUN. A literature study was conducted in order to identify these factors that affect the relationship between MUN and UUN. In this literature review a number of factors were established that affect the relationship between MUN and urinary N-excretion (UN) or UUN, such as dietary crude protein content (CP), intake of dietary salt and water, body weight, diurnal variation in plasma urea nitrogen concentration (PUN), exchange of urea between blood and milk, and heritability of MUN. Results of a quantitative meta-analysis where the effect of various physiological and dietary factors on the relationship between MUN and UN or UUN were studied confirmed the fact that CP affects the relationship between MUN and UUN and showed that by using information on MUN and CP more variation in UUN could be explained compared to using information on either MUN or CP alone. One of the factors established in the literature review that can affect the relationship between MUN and UUN is dietary salt content or drink water intake. In order to quantify the effect of dietary salt on MUN and UUN an experiment was carried out that investigated the effect of four dietary levels of sodium chloride (NaCl) on urea levels in blood plasma and milk and on UN and UUN. The results from this trial clearly showed a negative relationship between dietary NaCl content and MUN whereas UUN was not affected by NaCl intake and UN was slightly increased by increasing NaCl intake levels. The question arose whether the effect of dietary salt on MUN would be similar at high and low dietary protein levels as the renal mechanism of excretion and reabsorption of urea is affected by both dietary protein and salt intake. Therefore, the interaction between dietary salt and protein on UUN was tested in an experiment with two CP levels and two dietary NaCl levels. No interaction between dietary NaCl and CP on MUN was observed. However, the relationship between MUN and UUN was altered by the effect of salt intake. The literature review showed that diurnal variation in PUN and MUN can be substantial, and that this variation depends on factors such as time and frequency of feeding and milking. Insight in the dynamics of urea transport between blood of milk is important in order to model and predict variation in MUN over time under various feeding and milking regimes. To obtain quantitative insight in urea fluxes between blood and milk two experiments were conducted in which urea transport from blood to milk and vice versa was investigated by means of pulse dose injections of labeled [15N15N]urea in milk cisterns at various time intervals before milking. The results showed a rapid distribution of injected labeled urea throughout the milk in the mammary gland and substantial urea transport from milk to blood.

It is concluded that various factors that are discussed in this thesis contribute to variation in MUN that is not related to UUN. Taking these factors into account increases the applicability of MUN as a predictor of UUN.

Genetic diversity trends in twentieth century crop cultivars: a meta analysis
Wouw, M.J. van de; Hintum, T.J.L. van; Kik, C. ; Treuren, R. van; Visser, L. - \ 2010
Theoretical and Applied Genetics 120 (2010)6. - ISSN 0040-5752 - p. 1241 - 1252.
veredelde rassen - plantenveredeling - genetische diversiteit - meta-analyse - improved varieties - plant breeding - genetic diversity - meta-analysis - triticum-aestivum l. - assessing temporal-changes - spring wheat germplasm - hordeum-vulgare l. - winter-wheat - microsatellite markers - molecular diversity - ssr markers - breeding programs - gliadin alleles
In recent years, an increasing number of papers has been published on the genetic diversity trends in crop cultivars released in the last century using a variety of molecular techniques. No clear general trends in diversity have emerged from these studies. Meta analytical techniques, using a study weight adapted for use with diversity indices, were applied to analyze these studies. In the meta analysis, 44 published papers were used, addressing diversity trends in released crop varieties in the twentieth century for eight different field crops, wheat being the most represented. The meta analysis demonstrated that overall in the long run no substantial reduction in the regional diversity of crop varieties released by plant breeders has taken place. A significant reduction of 6% in diversity in the 1960s as compared with the diversity in the 1950s was observed. Indications are that after the 1960s and 1970s breeders have been able to again increase the diversity in released varieties. Thus, a gradual narrowing of the genetic base of the varieties released by breeders could not be observed. Separate analyses for wheat and the group of other field crops and separate analyses on the basis of regions all showed similar trends in diversity.
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