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.

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Chains as proper enrichment for intensively-farmed pigs?
Bracke, M.B.M. - \ 2018
In: Advances in Pig Welfare / Špinka, Marek, Woodhead Publishing - ISBN 9780081010129 - p. 167 - 197.
Growing-fattening pigs - weaners - enrichment
This chapter primarily compiles work in which the author (Marc Bracke) has been involved with providing science-based decision support on the question of what is proper enrichment material for intensively-farmed pigs as required by EC Directive 2001/93/EC. Proper manipulable material should primarily provide occupation (i.e. reduce boredom), and preferably reduce tail biting.
The RICHPIG model was built expressing enrichment value as a score on a scale from 0 to 10. Metal objects like short metal chains had the lowest score. Subsequently, the Dutch government banned the use of metal chains and most Dutch pig farmers attached a hard plastic ball or pipe to the prevalent, short metal chain. Unfortunately, our on-farm observations repeatedly suggested that this ‘enrichment’ may have reduced pig welfare, rather than improving it as intended by the Directive. So-called AMI (animal-material interaction) sensors can be used to (semi-)automatically record object manipulation by attaching a motion sensor to hanging objects. AMI-sensors may provide objective, flexible and feasible registration tools of enrichment value, but their application is still rather demanding. Exploratory data are presented to demonstrate the utility
of AMI-sensors. The enrichment value of short metal chains can be improved upon, e.g. by providing branched chains. This entails making chains longer, preferably reaching until the floor, and making them more readily available in a pig pen. To facilitate the process towards proper enrichment the principle of intelligent natural design (IND) is proposed. IND entails organising a repeated
selection process of the (currently) best-available enrichment material so as to gradually reduce pig boredom and enhance the opportunities for the rearing of pigs with intact tails. IND should start with basically all pig farmers implementing promising enrichment like the branched-chain design on their farms as soon as possible, followed by conducting small-scale on-farm experiments to compare and improve enrichment through sharing of available
knowledge. Suggestions are given as to how and why this novel approach can be
implemented to solve persistent animal-welfare problems like providing proper enrichment for intensively-farmed pigs.
Undernutrition management and the role of protein-enriched meals for older adults
Ziylan, Canan - \ 2016
Wageningen University. Promotor(en): Lisette de Groot; Stefanie Kremer; Annemien Haveman-Nies. - Wageningen : Wageningen University - ISBN 9789462579323 - 148
elderly - elderly nutrition - undernutrition - enrichment - protein - eating patterns - feeding behaviour - meals - nursing homes - ouderen - ouderenvoeding - ondervoeding - verrijking - eiwit - eetpatronen - voedingsgedrag - maaltijden - verpleeghuizen

Undernutrition is a major health problem in the growing elderly population. It is estimated that one in ten Dutch community-dwelling older adults is suffering from undernutrition, and one in three Dutch older adults who receive home care. Undernutrition may lead to many negative consequences, ranging from fatigue and falls to impaired immune function and death. This makes undernutrition an obvious target for preventive measures.

Undernutrition can be defined as “a state of nutrition in which a deficiency or excess (or imbalance) of energy, protein, and other nutrients causes measurable adverse effects on tissue/body form (body shape, size and composition) and function, and clinical outcome”. In addition, it is often described as protein energy malnutrition. Adequate protein intake may to some extent prevent and reverse this process. However, throughout ageing, it becomes increasingly difficult to reach adequate protein intake due to higher protein needs and lower protein intakes. Finding solutions to assist older adults in reaching their optimal protein intake is necessary.

In our overall research project, we considered 1.2g protein per kg weight per day (g/kg/d) as adequate protein intake. In Dutch community-dwelling older adults, protein intake is around 1.0 g/kg/d, implying room for improvement. However, it is possible that many of these older adults deal with physiological changes, medical conditions, and physical and mental limitations that impair their appetite and food provision. For these older adults with higher protein needs, merely recommending that they eat more would not be realistic. It would be more realistic to explore strategies that increase protein intake without having to increase food intake. This calls for the exploration of instruments that match the needs and preferences of older adults: protein-enriched regular products.

One particular group that can be identified as a target group for such products, are older adults who receive home care. Undernutrition prevalence is high in this group, which may be explained by their health problems that led to this dependence on home care. Likewise, many of these older adults also depend on meals-on-wheels. These meals-on-wheels recipients, regardless of whether they receive home care or not, often risk undernutrition too. In both these (overlapping) care-dependent groups, difficulties in adhering to energy and protein recommendations can be discerned. For this reason, enriching the readymade meals that these older adults receive may contribute to the prevention of protein undernutrition by increasing protein intake while keeping food intake the same. Here, protein enrichment instruments can be used to prevent undernutrition, but only when implemented in a timely manner. Adequate undernutrition management systems are therefore necessary to facilitate timely intervention, ensuring that the developed protein-enriched meals are actually offered and effective. For this reason, the overall aim of our research project was to gain insight into the current state of undernutrition management in community-dwelling older adults in the Netherlands and explore the role of protein-enriched regular products as a supportive instrument in protein undernutrition management.

In Study 1 (chapter 2) we explored the experiences of 22 Dutch nutrition and care professionals and researchers with undernutrition awareness, monitoring, and treatment among community-dwelling older adults. This qualitative study among, for example, dietitians, general practitioners, nurse practitioners, and home care nurses provided insight into the current bottlenecks within the existing undernutrition management guidelines. In these telephone interviews, these experts also discussed the current dietary behaviour problems of older adults and their impact on undernutrition risk. The experts’ experiences implied that undernutrition awareness is limited, among both older adults and care professionals. In addition, the interviewees were unclear about which professionals are responsible for monitoring and which monitoring procedures are preferred. The dietitians feel that they become involved too late, leading to decreased treatment effectiveness. In general, the interviewees desired more collaboration and a coherent and feasible allocation of responsibilities regarding undernutrition monitoring and treatment. This implied that the available guidelines on undernutrition management require more attention and facilitation.

In the following mixed-methods study (chapter 3), with interviews, we qualitatively explored the dietary behaviour and undernutrition risk of 12 Dutch elderly meals-on-wheels clients, one of the largest at-risk groups. We followed up on this information by quantifying the topics that emerged from the qualitative exploration of experienced bottlenecks in performing adequate dietary behaviour. For this, we used a survey among 333 meals-on-wheels clients. The interviews with elderly meals-on-wheels clients made clear that they have fixed and habitual eating patterns, while at the same time their appetite had decreased throughout the years. This was confirmed by the survey finding that regular portion size meals were perceived as too large by the oldest group aged over 75y. In addition, as the professionals suggested earlier, the interviewed elderly clients indeed showed limited awareness of undernutrition risk. Simultaneously, the survey showed that almost one in four elderly meals-on-wheels clients was undernourished. These findings led to the conclusion that staying close to the identified dietary habits may facilitate small yet effective modifications within these habits to prevent inadequate nutritional intake. Still, the limited awareness of undernutrition risk was expected to play a limiting role in whether clients believe they need dietary modifications. Consequently, informing them about this need could facilitate their motivation to implement modifications.

After learning about the general dietary behaviour of these older adults, we used this information for Study 3 (chapter 4). We developed two kinds of protein-enriched readymade meals that are in line with the needs and preferences of older adults: one of regular size (450g) and one of reduced size (400g). We tested these meals in a lab setting in 120 community-dwelling older adults in a single-blind randomised crossover trial. One day a week at lunchtime, for four weeks, participants had to consume and evaluate a readymade meal. Overall, regardless of portion size, the protein-enriched meals led to higher protein intakes in vital older adults in a lab setting during lunch. In this crossover study, the participants liked the protein-enriched meals and the regular meals equally. However, we did not find the expected lower ratings of satiety after the reduced-size meals, while one reduced-size enriched meal and another regular-size enriched meal led to higher ratings of subsequent satiety. This higher satiety in the enriched meals could lead to compensational behaviour on the remainder of the day.

After establishing that the protein-enriched meals were effective and acceptable in the lab setting, we moved to the homes of older adults to test the meals in a longer-term study in Study 4 (chapter 5). In this double-blind randomised controlled trial of two weeks, we also included protein-enriched bread to assess whether both this bread and the meals could increase daily protein intake to 1.2g/kg/d in 42 community-dwelling older adults to reach optimal protein intake. We found that the enriched products again led to higher protein intakes and a high liking. The mean protein intake per day was 14.6g higher in the intervention group, which amounted to a protein intake of 1.25g/kg/d, compared with 0.99g/kg/d in the control group. In addition, the meals scored 7.7 out of 10, while the bread scored 7.8 out of 10, which both were comparable with their regular counterparts. Lastly, we found no negative effect of compensational behaviour throughout the day. These promising findings indicated that we achieved a good match between older adults’ needs and preferences regarding protein intake.

In the general discussion of this thesis (chapter 6), we combined our learnings from the four studies to reflect on protein undernutrition management in community-dwelling older adults and the possible role of protein-enriched regular products. We have discussed a conceptual framework consisting of three wheels of protein undernutrition management. In the first wheel regarding awareness, we proposed that limited awareness of adequate nutrition and body composition forms the largest bottleneck in undernutrition management. When this awareness is generated among both older adults and professionals, it will benefit the second wheel of monitoring. Here, we argued that a policy and the actual facilitation of that policy are required for this monitoring to succeed. When the monitoring is performed adequately, in the third wheel, the appropriate treatment can be carried out. We discussed that personalisation and evaluation of this treatment are important conditions. All in all, the public health implications that we have discussed on the basis of our findings can be summarised by the three key messages that could help us ace in adequate protein undernutrition management: address awareness in both older adults and professionals, facilitate continuous collaboration between professionals, and offer protein-enriched products expediently.

Standardising the assessment of environmental enrichment and tail-docking legal requirements for finishing pigs in Europe
Hothersall, B. ; Whistance, L.K. ; Zedlacher, H. ; Algers, B. ; Andersson, E. ; Bracke, M.B.M. ; Courboulay, V. ; Ferrari, P. ; Leeb, C. ; Mullan, S. ; Nowicki, J. ; Meunier-Salaün, M.C. ; Schwarz, T. ; Stadig, L. ; Main, D. - \ 2016
Animal Welfare 25 (2016)4. - ISSN 0962-7286 - p. 499 - 515.
animal welfare - enrichment - inspector - legislation - pig - tail-docking - legisation
An online training package providing a concise synthesis of the scientific data underpinning EU legislation on enrichment and tail-docking of pigs was produced in seven languages, with the aim of improving consistency of professional judgements regarding legislation compliance on farms. In total, 158 participants who were official inspectors, certification scheme assessors and advisors from 16 EU countries completed an initial test and an online training package. Control group participants completed a second identical test before, and Training group participants after, viewing the training. In Section 1 of the test participants rated the importance of modifying environmental enrichment defined in nine scenarios from 1 (not important) to 10 (very important). Training significantly increased participants' overall perception of the need for change. Participants then rated nine risk factors for tail-biting from 1 (no risk) to 10 (high risk). After training scores were better correlated with risk rankings already described by scientists. Scenarios relating to tail-docking and management were then described. Training significantly increased the proportion of respondents correctly identifying that a farm without tail lesions should stop tail-docking. Finally, participants rated the importance of modifying enrichment in three further scenarios. Training increased ratings in all three. The pattern of results indicated that participants' roles influenced scores but overall the training improved: i) recognition of enrichments that, by virtue of their type or use by pigs, may be insufficient to achieve legislation compliance; ii) knowledge on risk factors for tail-biting; and iii) recognition of when routine tail-docking was occurring.
Glass transitions of barley starch and protein in the endosperm and isolated form
Donkelaar, L.H.G. van; Martinez, J.T. ; Frijters, H. ; Noordman, T.R. ; Boom, R.M. ; Goot, A.J. van der - \ 2015
Food Research International 72 (2015). - ISSN 0963-9969 - p. 241 - 246.
air classification - temperature - enrichment - fractions - flours
When studying the glass-to-rubber transition inside natural materials, it is important to take into account not only the moisture content but also the moisture distribution over the components in the material. We measured the Tg of protein and starch isolated from barley at different moisture contents using differential scanning calorimetry (DSC) (heating rate 10 °C/min) and by thermo mechanical compression tests (TMCT) (heating rate 2 °C/min). The measurement of the Tg of partially crystalline materials, such as barley starch, is more difficult using TMCT because the mechanical effect of expansion of these materials is smaller. For both measurement sets the glass transition lines were modeled using the Gordon–Taylor equation. The lines were adapted for the differences in moisture content over the endosperm by using the sorption isotherms of isolated barley starch and protein and whole barley endosperm. The glass transition lines measured by TMCT were closer together than the ones measured by DSC
High rates of anaerobic oxidation of methane, ethane and propane coupled to thiosulphate reduction
Suarez Zuluaga, D.A. ; Weijma, J. ; Timmers, P.H.A. ; Buisman, C.J.N. - \ 2015
Environmental Science and Pollution Research 22 (2015)5. - ISSN 0944-1344 - p. 3697 - 3704.
sulfate-reducing bacteria - marine-sediments - electron-donor - sulfur cycle - aarhus bay - consumption - denmark - disproportionation - bioreactor - enrichment
Anaerobic methane oxidation coupled to sulphate reduction and the use of ethane and propane as electron donors by sulphate-reducing bacteria represent new opportunities for the treatment of streams contaminated with sulphur oxyanions. However, growth of microbial sulphate-reducing populations with methane, propane or butane is extremely slow, which hampers research and development of bioprocesses based on these conversions. Thermodynamic calculations indicate that the growth rate with possible alternative terminal electron acceptors such as thiosulphate and elemental sulphur may be higher, which would facilitate future research. Here, we investigate the use of these electron acceptors for oxidation of methane, ethane and propane, with marine sediment as inoculum. Mixed marine sediments originating from Aarhus Bay (Denmark) and Eckernförde Bay (Germany) were cultivated anaerobically at a pH between 7.2 and 7.8 and a temperature of 15 °C in the presence of methane, ethane and propane and various sulphur electron acceptors. The sulphide production rates in the conditions with methane, ethane and propane with sulphate were respectively 2.3, 2.2 and 1.8 µmol S L-1 day-1. For sulphur, no reduction was demonstrated. For thiosulphate, the sulphide production rates were up to 50 times higher compared to those of sulphate, with 86.2, 90.7 and 108.1 µmol S L-1 day-1 for methane, ethane and propane respectively. This sulphide production was partly due to disproportionation, 50 % for ethane but only 7 and 14 % for methane and propane respectively. The oxidation of the alkanes in the presence of thiosulphate was confirmed by carbon dioxide production. This is, to our knowledge, the first report of thiosulphate use as electron acceptor with ethane and propane as electron donors. Additionally, these results indicate that thiosulphate is a promising electron acceptor to increase start-up rates for sulphate-reducing bioprocesses coupled to short-chain alkane oxidation.
Genome-wide survey indicates involvement of loci on canine chromosomes 7 and 31 in patellar luxation in flat-coated retrievers
Lavrijsen, I.C.M. ; Leegwater, P.A.J. ; Wangdee, C. ; Steenbeek, F.G. van; Schwencke, M. ; Breur, G.J. ; Meutstege, F.J. ; Nijman, I.J. ; Cuppen, E. ; Heuven, H.C.M. ; Hazewinkel, H.A.W. - \ 2014
BMC Genetics 15 (2014). - ISSN 1471-2156
dogs - breed - frequency - association - enrichment
Background: Patellar luxation is an orthopedic disorder in which the patella moves out of its normal location within the femoral trochlea of the knee and it can lead to osteoarthritis, lameness, and pain. In dogs it is a heritable trait, with both environmental and genetic factors contributing to the phenotype. The prevalence of patellar luxation in the Dutch Flat-Coated Retriever population is 24%. In this study, we investigated the molecular genetics of the disorder in this population. Results: Genome-wide association analysis of 15,823 single nucleotide polymorphisms (SNPs) in 45 cases and 40 controls revealed that patellar luxation was significantly associated with a region on chromosome CFA07, and possibly with regions on CFA03, CFA31, and CFA36. The exons of the genes in these regions, 0.5 Mb combined, were analyzed further. These exons from 15 cases and a pooled sample from 15 controls were enriched using custom genomic hybridization arrays and analyzed by massive parallel DNA sequencing. In total 7257 variations were detected. Subsequently, a selection of 144 of these SNPs were genotyped in 95 Flat-Coated Retrievers. Nine SNPs, in eight genes on CFA07 and CFA31, were associated with patellar luxation (P <10(-4)). Genotyping of these SNPs in samples from a variety of breeds revealed that the disease-associated allele of one synonymous SNP in a pseudogene of FMO6 was unique to Flat-Coated Retrievers. Conclusion: Genome-wide association analysis followed by targeted DNA sequencing identified loci on chromosomes 7 and 31 as being involved in patellar luxation in the Flat-Coated Retriever breed.
Effect of temperature on denitrifying methanotrophic activity of 'Candidatus Methylomirabilis oxyfera'
Kampman, C. ; Piai, L. ; Hendrickx, T.L.G. ; Temmink, B.G. ; Zeeman, G. ; Buisman, C.J.N. - \ 2014
Water Science and Technology 70 (2014)10. - ISSN 0273-1223 - p. 1683 - 1689.
waterzuivering - denitrificatie - biologische behandeling - water treatment - denitrification - biological treatment - anaerobic methane oxidation - municipal waste-water - nitrogen removal - membrane bioreactor - sewage-treatment - uasb-digester - degrees-c - bacteria - enrichment - nitrite
The activity of denitrifying methanotrophic bacteria at 11-30 degrees C was assessed in short-term experiments. The aim was to determine the feasibility of applying denitrifying methanotrophic bacteria in low-temperature anaerobic wastewater treatment. This study showed that biomass enriched at 21 degrees C had an optimum temperature of 20-25 degrees C and that activity dropped as temperature was increased to 30 degrees C. Biomass enriched at 30 degrees C had an optimum temperature of 25-30 degrees C. These results indicated that biomass from low-temperature inocula adjusted to the enrichment temperature and that low-temperature enrichment is suitable for applications in low-temperature wastewater treatment. Biomass growth at
vanI: a novel d-Ala-d-Lac vancomycin resistance gene cluster found in Desulfitobacterium hafniense
Kruse, T. ; Levisson, M. ; Vos, W.M. de; Smidt, H. - \ 2014
Microbial Biotechnology 7 (2014)5. - ISSN 1751-7907 - p. 456 - 466.
comparative-analysis system - antibiotic-resistance - enterococcus-faecium - genome sequence - streptomyces-coelicolor - bacteria - enrichment - evolution - resistome - alignment
The glycopeptide vancomycin was until recently considered a drug of last resort against Gram-positive bacteria. Increasing numbers of bacteria, however, are found to carry genes that confer resistance to this antibiotic. So far, 10 different vancomycin resistance clusters have been described. A chromosomal vancomycin resistance gene cluster was previously described for the anaerobic Desulfitobacterium hafniense Y51. We demonstrate that this gene cluster, characterized by its d-Ala-d-Lac ligase-encoding vanI gene, is present in all strains of D.¿hafniense, D.¿chlororespirans and some strains of Desulfosporosinus spp. This gene cluster was not found in vancomycin-sensitive Desulfitobacterium or Desulfosporosinus spp., and we show that this antibiotic resistance can be exploited as an intrinsic selection marker for Desulfitobacterium hafniense and D.¿chlororespirans. The gene cluster containing vanI is phylogenetically only distantly related with those described from soil and gut bacteria, but clusters instead with vancomycin resistance genes found within the phylum Actinobacteria that include several vancomycin-producing bacteria. It lacks a vanH homologue, encoding a D-lactate dehydrogenase, previously thought to always be present within vancomycin resistance gene clusters. The location of vanH outside the resistance gene cluster likely hinders horizontal gene transfer. Hence, the vancomycin resistance cluster in D.¿hafniense should be regarded a novel one that we here designated vanI after its unique d-Ala-d-Lac ligase
A Next-Generation Sequencing Method for Genotyping-by-Sequencing of Highly Heterozygous Autotetraploid Potato
Uitdewilligen, J.G.A.M.L. ; Wolters, A.M.A. ; hoop, B.B. D'; Borm, T.J.A. ; Visser, R.G.F. ; Eck, H.J. van - \ 2013
PLoS ONE 8 (2013)5. - ISSN 1932-6203 - 14 p.
single-nucleotide polymorphisms - genome-wide association - chloroplast dna - solanum-tuberosum - agronomic traits - hybrid selection - discovery - enrichment - resistance - diversity
Assessment of genomic DNA sequence variation and genotype calling in autotetraploids implies the ability to distinguish among five possible alternative allele copy number states. This study demonstrates the accuracy of genotyping-by-sequencing (GBS) of a large collection of autotetraploid potato cultivars using next-generation sequencing. It is still costly to reach sufficient read depths on a genome wide scale, across the cultivated gene pool. Therefore, we enriched cultivar-specific DNA sequencing libraries using an in-solution hybridisation method (SureSelect). This complexity reduction allowed to confine our study to 807 target genes distributed across the genomes of 83 tetraploid cultivars and one reference (DM 1–3 511). Indexed sequencing libraries were paired-end sequenced in 7 pools of 12 samples using Illumina HiSeq2000. After filtering and processing the raw sequence data, 12.4 Gigabases of high-quality sequence data was obtained, which mapped to 2.1 Mb of the potato reference genome, with a median average read depth of 63× per cultivar. We detected 129,156 sequence variants and genotyped the allele copy number of each variant for every cultivar. In this cultivar panel a variant density of 1 SNP/24 bp in exons and 1 SNP/15 bp in introns was obtained. The average minor allele frequency (MAF) of a variant was 0.14. Potato germplasm displayed a large number of relatively rare variants and/or haplotypes, with 61% of the variants having a MAF below 0.05. A very high average nucleotide diversity (p = 0.0107) was observed. Nucleotide diversity varied among potato chromosomes. Several genes under selection were identified. Genotyping-by-sequencing results, with allele copy number estimates, were validated with a KASP genotyping assay. This validation showed that read depths of ~60–80× can be used as a lower boundary for reliable assessment of allele copy number of sequence variants in autotetraploids. Genotypic data were associated with traits, and alleles strongly influencing maturity and flesh colour were identified.
Genomic Treasure Troves: Complet Genome Sequencing of Herbarium and Insect Museum Specimens
Staats, M. ; Erkens, R.H.J. ; Vossenberg, B. van de; Wieringa, J.J. ; Kraaijeveld, K. ; Stielow, B. ; Geml, J. ; Richardson, J.E. ; Bakker, F.T. - \ 2013
PLoS ONE 8 (2013)7. - ISSN 1932-6203
ancient dna-sequences - miscoding lesions - extraction - amplification - patterns - fungi - plant - enrichment - evolution - alignment
Unlocking the vast genomic diversity stored in natural history collections would create unprecedented opportunities for genome-scale evolutionary, phylogenetic, domestication and population genomic studies. Many researchers have been discouraged from using historical specimens in molecular studies because of both generally limited success of DNA extraction and the challenges associated with PCR-amplifying highly degraded DNA. In today's next-generation sequencing (NGS) world, opportunities and prospects for historical DNA have changed dramatically, as most NGS methods are actually designed for taking short fragmented DNA molecules as templates. Here we show that using a standard multiplex and paired-end Illumina sequencing approach, genome-scale sequence data can be generated reliably from dry-preserved plant, fungal and insect specimens collected up to 115 years ago, and with minimal destructive sampling. Using a reference-based assembly approach, we were able to produce the entire nuclear genome of a 43-year-old Arabidopsis thaliana (Brassicaceae) herbarium specimen with high and uniform sequence coverage. Nuclear genome sequences of three fungal specimens of 22–82 years of age (Agaricus bisporus, Laccaria bicolor, Pleurotus ostreatus) were generated with 81.4–97.9% exome coverage. Complete organellar genome sequences were assembled for all specimens. Using de novo assembly we retrieved between 16.2–71.0% of coding sequence regions, and hence remain somewhat cautious about prospects for de novo genome assembly from historical specimens. Non-target sequence contaminations were observed in 2 of our insect museum specimens. We anticipate that future museum genomics projects will perhaps not generate entire genome sequences in all cases (our specimens contained relatively small and low-complexity genomes), but at least generating vital comparative genomic data for testing (phylo)genetic, demographic and genetic hypotheses, that become increasingly more horizontal. Furthermore, NGS of historical DNA enables recovering crucial genetic information from old type specimens that to date have remained mostly unutilized and, thus, opens up a new frontier for taxonomic research as well.
Climate Change and Potato Production in Contrasting South African Agro-ecosystems 1. Effects on Land and Water Use Efficiencies
Haverkort, A.J. ; Franke, A.C. ; Engelbrecht, F.A. ; Steyn, J.M. - \ 2013
Potato Research 56 (2013)1. - ISSN 0014-3065 - p. 31 - 50.
elevated carbon-dioxide - solanum-tuberosum l. - co2 concentration - atmospheric co2 - crop yields - model - growth - simulation - enrichment - quality
Explorations of the impact of climate change on potential potato yields were obtained by downscaling the projections of six different coupled climate models to high spatial resolution over southern Africa. The simulations of daily maximum and minimum temperatures, precipitation, wind speed, and solar radiation were used as input to run the crop growth model LINTUL-Potato. Pixels representative for potato growing areas were selected for four globally occurring agro-ecosystems: rainy and dry winter and summer crops. The simulated inter-annual variability is much greater for rainfall than for temperature. Reference evapotranspiration and radiation are projected to hardly decline over the 90-year period, whilst temperatures are projected to rise significantly by about 1.9 °C. From literature, it was found that radiation use efficiency of potato increased with elevated CO2 concentrations by almost 0.002 g¿MJ-1¿ppm-1. This ratio was used to calculate the CO2 effect on yields between 1960 and 2050, when CO2 concentration increases from 315 to 550 ppm. Within this range, evapotranspiration by the potato crop was reduced by about 13% according to literature. Simulated yield increase was strongest in the Mediterranean-type winter crop (+37%) and least under Mediterranean summer (+12%) and relatively warm winter conditions (+14%) closer to the equator. Water use efficiency also increased most in the cool rainy Mediterranean winter (+45%) and least so in the winter crop closer to the equator (+14%). It is concluded from the simulations that for all four agro-ecosystems possible negative effects of rising temperatures and reduced availability of water for potato are more than compensated for by the positive effect of increased CO2 levels on water use efficiency and crop productivity.
Does predator interference cause alternative stable states in multispecies communities?
Feng, J. ; Dakos, V. ; Nes, E.H. van - \ 2012
Theoretical Population Biology 82 (2012)3. - ISSN 0040-5809 - p. 170 - 176.
mutual interference - marine ecosystems - shallow lakes - regime shifts - thresholds - enrichment - paradox - stabilization - resilience - stability
Whereas it is well known that simple ecological mechanisms may promote stability in simple species models, their consequences for stability and resilience in multispecies communities are largely unexplored. Here, we studied the effect of predator interference on the occurrence of alternative attractors and complex dynamics in randomly constructed multispecies predator-prey communities. We studied three types of interference: random interference ("asymmetric"), random interference but symmetrical between pairs of predators ("symmetric"), and interference among only the same species ("conspecific"). In all cases predator interference increased the average number of alternative attractors, whereas at the same time it reduced the emergence of oscillatory or chaotic dynamics. Our findings demonstrate a contrasting effect of predator interference on the stability of a community: on the one hand it reduces cycles and chaos in the dynamics, on the other hand predator interference increases the likelihood that communities may undergo critical transitions between multiple stable states.
Effects of irradiance and light spectrum on growth of the scleractinian coral Galaxea
Wijgerde, T.H.M. ; Henkemans, P. ; Osinga, R. - \ 2012
Aquaculture 344-349 (2012). - ISSN 0044-8486 - p. 188 - 193.
carbonate-ion concentration - stylophora-pistillata - ocean acidification - skeletal growth - climate-change - photosynthesis - calcification - zooxanthellae - temperature - enrichment
Due to global degradation of coral reefs and high demand for scleractinian corals, aquaculture of these marine organisms is gaining importance. To make coral aquaculture economically viable, optimisation of culture protocols is vital. We determined the effects of irradiance and light spectrum on the growth of a model scleractinian coral species, Galaxea fascicularis (Linnaeus 1767). Single polyps (n=10) were cultured under six different treatments; LED (light emitting diode) at a PPFD of 40-60, 125-150 and 275-325 mu mol m(-2) s(-1); and LEP (light emitting plasma) at a PPFD of 40-60, 125-150 and 275-325 mu mol m (2) s (1). Specific growth and survival rates were monitored over a 69-day interval. Mean specific growth rates were 0.031 +/- 0.006 day(-1) for the LED 40-60 treatment, 0.030 +/- 0.007 day(-1) for LED 125-150, 0.022 +/- 0.009 day(-1) for LED 275-325, 0.024 +/- 0.011 day(-1) for LEP 40-60, 0.040 +/- 0.008 day(-1) for LEP 125-150, and 0.031 +/- 0.006 day(-1) for LEP 275-325. Coral survival rate at the end of the growth interval was 95%. A significant main effect of irradiance on coral specific growth rate was found (factorial ANOVA, P=0.018), whereas spectrum did not show a significant main effect (factorial ANOVA, P=0.085). A significant interactive effect between irradiance and spectrum was found (factorial ANOVA, P=0.013), as LEP lighting resulted in higher coral growth rates at the two higher irradiance levels applied. The effect of irradiance and its interaction with spectrum were likely modulated by water flow rates. Our results show that balanced as well as light sources skewed towards the blue part of the spectrum result in high coral growth. Specifically, LEP and LED have shown to be suitable lighting technologies for coral aquaculture, where LEP yields higher G. fascicularis growth rates at higher irradiance levels. (c) 2012 Elsevier B.V. All rights reserved.
Serum protein profiles as potential biomarkers for infectious disease status in pigs
Koene, M.G.J. ; Mulder, H.A. ; Stockhofe, N. ; Kruijt, L. ; Smits, M.A. - \ 2012
BMC Veterinary Research 8 (2012). - ISSN 1746-6148 - 14 p.
low-abundance proteins - acute-phase proteins - clinical proteomics - mass-spectrometry - ovine serum - discovery - classification - technology - enrichment - samples
Background: In veterinary medicine and animal husbandry, there is a need for tools allowing the early warning of diseases. Preferably, tests should be available that warn farmers and veterinarians during the incubation periods of disease and before the onset of clinical signs. The objective of this study was to explore the potential of serum protein profiles as an early biomarker for infectious disease status. Serum samples were obtained from an experimental pig model for porcine circovirus-associated disease (PCVAD), consisting of Porcine Circovirus type 2 (PCV2) infection in combination with either Porcine Parvovirus (PPV) or Porcine Reproductive and Respiratory Syndrome virus (PRRSV). Sera were collected before and after onset of clinical signs at day 0, 5 and 19 post infection. Serum protein profiles were evaluated against sera from non-infected control animals. Results: Protein profiles were generated by SELDI-TOF mass spectrometry in combination with the Proteominer (TM) technology to enrich for low-abundance proteins. Based on these protein profiles, the experimentally infected pigs could be classified according to their infectious disease status. Before the onset of clinical signs 88% of the infected animals could be classified correctly, after the onset of clinical sigs 93%. The sensitivity of the classification appeared to be high. The protein profiles could distinguish between separate infection models, although specificity was moderate to low. Classification of PCV2/PRRSV infected animals was superior compared to PCV2/PPV infected animals. Limiting the number of proteins in the profiles (ranging from 568 to 10) had only minor effects on the classification performance. Conclusions: This study shows that serum protein profiles have potential for detection and identification of viral infections in pigs before clinical signs of the disease become visible.
Kinetics of ferrous iron oxidation by batch and continuous cultures of thermoacidophilic Archaea at extremely low pH of 1.1–1.3
Gonzalez-Contreras, P.A. ; Weijma, J. ; Buisman, C.J.N. - \ 2012
Applied Microbiology and Biotechnology 93 (2012)3. - ISSN 0175-7598 - p. 1295 - 1303.
sulfolobus-metallicus - acidianus-sulfidivorans - metallosphaera-sedula - microorganisms - concentrate - pyrite - chalcopyrite - biooxidation - acidophiles - enrichment
The extreme acid conditions required for scorodite (FeAsO4·2H2O) biomineralization (pH below 1.3) are suboptimal for growth of most thermoacidophilic Archaea. With the objective to develop a continuous process suitable for biomineral production, this research focuses on growth kinetics of thermoacidophilic Archaea at low pH conditions. Ferrous iron oxidation rates were determined in batch-cultures at pH 1.3 and a temperature of 75°C for Acidianus sulfidivorans, Metallosphaera prunea and a mixed Sulfolobus culture. Ferrous iron and CO2 in air were added as sole energy and carbon source. The highest growth rate (0.066 h-1) was found with the mixed Sulfolobus culture. Therefore, this culture was selected for further experiments. Growth was not stimulated by increase of the CO2 concentration or by addition of sulphur as an additional energy source. In a CSTR operated at the suboptimal pH of 1.1, the maximum specific growth rate of the mixed culture was 0.022 h-1, with ferrous iron oxidation rates of 1.5 g L-1 d-1. Compared to pH 1.3, growth rates were strongly reduced but the ferrous iron oxidation rate remained unaffected. Influent ferrous iron concentrations above 6 g L-1 caused instability of Fe2+ oxidation, probably due to product (Fe3+) inhibition. Ferric-containing, nano-sized precipitates of K-jarosite were found on the cell surface. Continuous cultivation stimulated the formation of an exopolysaccharide-like substance. This indicates that biofilm formation may provide a means of biomass retention. Our findings showed that stable continuous cultivation of a mixed iron-oxidizing culture is feasible at the extreme conditions required for continuous biomineral formation.
Two new effective semiselective crystal violet pectate media for isolation of Pectobacterium and Dickeya
Hélias, V. ; Hamon, P. ; Huchet, E. ; Wolf, J.M. van der; Andrivon, D. - \ 2012
Plant Pathology 61 (2012)2. - ISSN 0032-0862 - p. 339 - 345.
soft-rot erwinias - carotovora subsp atroseptica - selective medium - sp-nov. - potato - chrysanthemi - enrichment - soil
Pectolytic bacteria, including Pectobacterium spp. and Dickeya spp., are best isolated on crystal violet pectate (CVP), a semiselective medium containing pectin. The source of pectin is essential, because pectolytic bacteria are not able to degrade all of them. The aims of this study were to identify a new pectin source and to perfect formulations of semiselective CVP media to isolate the pectolytic bacteria Pectobacterium spp. and Dickeya spp. from different environmental compartments (plants, soil and water). The AG366 pectin, selected after screening six different formulations, was incorporated into single-layer (SL-CVPAG366) and double-layer (DL-CVPAG366) CVP media. Both media were compared with those based on Bulmer, Sigma-Aldrich and Slendid-Burger pectins, using 39 Pectobacterium and Dickeya strains. All strains formed deep cavities on AG366-CVPs, whereas nine did not produce cavities on Bulmer or Sigma-Aldrich media. Recovery rates were similar on DL-CVPAG366, Sigma-Aldrich and Bulmer CVPs for a given taxon, and did not differ significantly between SL- and DL-CVPAG366. Pectolytic bacteria were successfully isolated on both media from field samples of diseased potatoes, carrots, tobacco, onions, radishes and ornamentals. AG366 is thus a high-performance pectin source for the elaboration of CVP media suitable to isolate Dickeya and Pectobacterium. It is also efficient for enrichment purposes in liquid medium. The validation of AG366 as an improved source of pectin to recover the polyphagous Pectobacterium and Dickeya in different environmental compartments is essential given the current worldwide emergence and recrudescence of these bacteria.
Chromothripsis is a common mechanism driving genomic rearrangements in primary and metastatic colorectal cancer
Kloosterman, W.P. ; Hoogstraat, M. ; Paling, O. ; Tavakoli-Yaraki, M. ; Renkens, I. ; Vermaat, J.S. ; Roosmalen, M.J. van; Lieshout, S. van; Nijman, I.J. ; Roessingh, W. ; Slot, R. van 't; Belt, J. van de - \ 2011
Genome Biology 12 (2011)10. - ISSN 1474-7596 - 11 p.
human breast - pancreatic-cancer - resolution - evolution - patterns - mutation - progression - landscapes - enrichment - genes
Background - Structural rearrangements form a major class of somatic variation in cancer genomes. Local chromosome shattering, termed chromothripsis, is a mechanism proposed to be the cause of clustered chromosomal rearrangements and was recently described to occur in a small percentage of tumors. The significance of these clusters for tumor development or metastatic spread is largely unclear. Results - We used genome-wide long mate-pair sequencing and SNP array profiling to reveal that chromothripsis is a widespread phenomenon in primary colorectal cancer and metastases. We find large and small chromothripsis events in nearly every colorectal tumor sample and show that several breakpoints of chromothripsis clusters and isolated rearrangements affect cancer genes, including NOTCH2, EXO1 and MLL3. We complemented the structural variation studies by sequencing the coding regions of a cancer exome in all colorectal tumor samples and found somatic mutations in 24 genes, including APC, KRAS, SMAD4 and PIK3CA. A pairwise comparison of somatic variations in primary and metastatic samples indicated that many chromothripsis clusters, isolated rearrangements and point mutations are exclusively present in either the primary tumor or the metastasis and may affect cancer genes in a lesion-specific manner. Conclusions - We conclude that chromothripsis is a prevalent mechanism driving structural rearrangements in colorectal cancer and show that a complex interplay between point mutations, simple copy number changes and chromothripsis events drive colorectal tumor development and metastasis
An intracellular pH gradient in the anammox bacterium Kuenenia stuttgartiensis as evaluated by P-31 NMR
Star, W.R.L. van der; Dijkema, C. ; Waard, P. de; Picioreanu, C. ; Strous, M. ; Loosdrecht, M.C.M. van - \ 2010
Applied Microbiology and Biotechnology 86 (2010)1. - ISSN 0175-7598 - p. 311 - 317.
ammonium-oxidizing bacteria - nuclear-magnetic-resonance - proton gradients - 4 genera - compartmentation - enrichment - oxidation - reactor - cells - identification
The cytoplasm of anaerobic ammonium oxidizing (anammox) bacteria consists of three compartments separated by membranes. It has been suggested that a proton motive force may be generated over the membrane of the innermost compartment, the "anammoxosome". P-31 nuclear magnetic resonance (NMR) spectroscopy was employed to investigate intracellular pH differences in the anammox bacterium Kuenenia stuttgartiensis. With in vivo NMR, spectra were recorded of active, highly concentrated suspensions of K. stuttgartiensis in a wide-bore NMR tube. At different external pH values, two stable and distinct phosphate peaks were apparent in the recorded spectra. These peaks were equivalent with pH values of 7.3 and 6.3 and suggested the presence of a proton motive force over an intracytoplasmic membrane in K. stuttgartiensis. This study provides for the second time-after discovery of acidocalcisome-like compartments in Agrobacterium tumefaciens-evidence for an intracytoplasmic pH gradient in a chemotrophic prokaryotic cell
Hokverrijking om in de knaagbehoefte van konijnen te voorzien: een literatuurstudie = Environmental enrichment to fulfill gnawing requirements in rabbits: a literature study
Rommers, J.M. ; Jong, I.C. de - \ 2010
Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 396) - 16
dierenwelzijn - konijnen - verrijking - hokken - zachthout - ruwvoer (forage) - animal welfare - rabbits - enrichment - pens - softwoods - forage
This report is a literature study to environmental enrichment in rabbits, that possibly fulfills the gnawing requirements
Food Quality in Producer-Grazer Models: A Generalized Analysis
Stiefs, D. ; Voorn, G.A.K. van; Kooi, B.W. ; Feudel, U. ; Gross, T. - \ 2010
American Naturalist 176 (2010)3. - ISSN 0003-0147 - p. 367 - 380.
predator-prey interactions - population-dynamics - functional-response - stability - systems - stoichiometry - enrichment - connectance - coexistence - competition
Stoichiometric constraints play a role in the dynamics of natural populations but are not explicitly considered in most mathematical models. Recent theoretical works suggest that these constraints can have a significant impact and should not be neglected. However, it is not yet resolved how stoichiometry should be integrated in population dynamical models, as different modeling approaches are found to yield qualitatively different results. Here we investigate a unifying framework that reveals the differences and commonalities between previously proposed models for producer-grazer systems. Our analysis reveals that stoichiometric constraints affect the dynamics mainly by increasing the intraspecific competition between producers and by introducing a variable biomass conversion efficiency. The intraspecific competition has a strongly stabilizing effect on the system, whereas the variable conversion efficiency resulting from a variable food quality is the main determinant for the nature of the instability once destabilization occurs. Only if the food quality is high can an oscillatory instability, as in the classical paradox of enrichment, occur. While the generalized model reveals that the generic insights remain valid in a large class of models, we show that other details such as the specific sequence of bifurcations encountered in enrichment scenarios can depend sensitively on assumptions made in modeling stoichiometric constraints.
Boi-energy retains it's mitigration potential under elevated CO2
Liberloo, M. ; Luyssaert, S. ; Hoosbeek, M.R. - \ 2010
PLoS ONE 5 (2010)7. - ISSN 1932-6203 - 11 p.
rotation poplar plantation - carbon sequestration - coniferous forests - biomass production - greenhouse gases - enrichment - biofuels - soil - productivity - increases
Background - If biofuels are to be a viable substitute for fossil fuels, it is essential that they retain their potential to mitigate climate change under future atmospheric conditions. Elevated atmospheric CO2 concentration [CO2] stimulates plant biomass production; however, the beneficial effects of increased production may be offset by higher energy costs in crop management. Methodology/Main Findings - We maintained full size poplar short rotation coppice (SRC) systems under both current ambient and future elevated [CO2] (550 ppm) and estimated their net energy and greenhouse gas balance. We show that a poplar SRC system is energy efficient and produces more energy than required for coppice management. Even more, elevated [CO2] will increase the net energy production and greenhouse gas balance of a SRC system with 18%. Managing the trees in shorter rotation cycles (i.e., 2 year cycles instead of 3 year cycles) will further enhance the benefits from elevated [CO2] on both the net energy and greenhouse gas balance. Conclusions/Significance - Adapting coppice management to the future atmospheric [CO2] is necessary to fully benefit from the climate mitigation potential of bio-energy systems. Further, a future increase in potential biomass production due to elevated [CO2] outweighs the increased production costs resulting in a northward extension of the area where SRC is greenhouse gas neutral. Currently, the main part of the European terrestrial carbon sink is found in forest biomass and attributed to harvesting less than the annual growth in wood. Because SRC is intensively managed, with a higher turnover in wood production than conventional forest, northward expansion of SRC is likely to erode the European terrestrial carbon sink
Rope test may indicate efficacy of tail-biting treatments in growing pigs
Bracke, M.B.M. - \ 2009
Animal Welfare 18 (2009)3. - ISSN 0962-7286 - p. 263 - 266.
attraction - blood - enrichment - models
Tail biting is a most serious welfare problem in pigs raised for slaughter. In instances of an outbreak of tail biting, scientists have recommended that farmers take measures such as removal of affected animals, provision of enrichment materials and application of repellents to the pigs' tails. However, no scientific study has ever confirmed the efficacy of any of these suggestions in counteracting an ongoing outbreak. Here, the efficacy of two repellent ointments, Dippel's oil and Stockholm tar, were examined in a tail-chew test. For this, a novel piece of nylon rope was used as a tail model to measure biting behaviour semi-automatically in 24 single-sex groups of growing pigs (total 264 pigs). Repeated measures analysis showed no effect of time, gender or unit (12 pens per unit), but a highly significant effect of treatment, in that both Stockholm tar and Dippel's oil significantly reduced rope manipulation compared to controls. These results suggest that Stockholm tar and Dippel's oil may be effective in reducing tail biting. The approach taken may be valuable in further testing of strategies to reduce tail biting and improving pig welfare
The impact of long-term elevated CO2 on C and N retention in stable SOM pools
Graaff, M.A. de; Kessel, C. van; Six, J. - \ 2008
Plant and Soil 303 (2008)1-feb. - ISSN 0032-079X - p. 311 - 321.
trifolium-repens l - atmospheric co2 - carbon-dioxide - nitrogen mineralization - soil - grassland - enrichment - responses - ecosystem - dynamics
Elevated atmospheric CO2 frequently increases plant production and concomitant soil C inputs, which may cause additional soil C sequestration. However, whether the increase in plant production and additional soil C sequestration under elevated CO2 can be sustained in the long-term is unclear. One approach to study C-N interactions under elevated CO2 is provided by a theoretical framework that centers on the concept of progressive nitrogen limitation (PNL). The PNL concept hinges on the idea that N becomes less available with time under elevated CO2. One possible mechanism underlying this reduction in N availability is that N is retained in long-lived soil organic matter (SOM), thereby limiting plant production and the potential for soil C sequestration. The long-term nature of the PNL concept necessitates the testing of mechanisms in field experiments exposed to elevated CO2 over long periods of time. The impact of elevated CO2 and N-15 fertilization on L. perenne and T. repens monocultures has been studied in the Swiss FACE experiment for ten consecutive years. We applied a biological fractionation technique using long-term incubations with repetitive leaching to determine how elevated CO2 affects the accumulation of N and C into more stable SOM pools. Elevated CO2 significantly stimulated retention of fertilizer-N in the stable pools of the soils covered with L. perenne receiving low and high N fertilization rates by 18 and 22%, respectively, and by 45% in the soils covered by T. repens receiving the low N fertilization rate. However, elevated CO2 did not significantly increase stable soil C formation. The increase in N retention under elevated CO2 provides direct evidence that elevated CO2 increases stable N formation as proposed by the PNL concept. In the Swiss FACE experiment, however, plant production increased under elevated CO2, indicating that the additional N supply through fertilization prohibited PNL for plant production at this site. Therefore, it remains unresolved why elevated CO2 did not increase labile and stable C accumulation in these systems.
Microbial enrichment of torrefied grass fibers : a novel ingredient of potting soil
Trifonova, R.D. - \ 2008
University of Groningen. Promotor(en): J.D. van Elsas, co-promotor(en): Joeke Postma. - [S.l.] : S.n. - ISBN 9789036736695 - 146
groeimedia - vezels - hooi - grassen - microbiële flora - verrijking - verbeteraars - fytotoxiciteit - growing media - fibres - hay - grasses - microbial flora - enrichment - amendments - phytotoxicity
Transcriptome and proteonome profiling of colon mucosa from quercetin fed F344 rats point to tumor preventive mechanisms, increased mitochondrial fatty acid degradation and decreased glycolysis
Dihal, A.A. ; Hendriksen, P.J.M. ; Charif, H. ; Dekker, L.J. ; IJsselstijn, L. ; Boer, V.C.J. de; Alink, G.M. ; Rietjens, I.M.C.M. ; Woutersen, R.A. ; Stierum, R.H. - \ 2008
Proteomics 8 (2008)1. - ISSN 1615-9853 - p. 45 - 61.
gene-expression - colorectal-cancer - suppresses growth - messenger-rna - cell-line - identification - antioxidant - enrichment - pathway - targets
Quercetin has been shown to act as an anticarcinogen in experimental colorectal cancer (CRC). The aim of the present study was to characterize transcriptome and proteome changes occurring in the distal colon mucosa of rats supplemented with 10 g quercetin/kg diet for 11 wk. Transcriptome data analyzed with Gene Set Enrichment Analysis showed that quercetin significantly downregulated the potentially oncogenic mitogen-activated protein kinase (Mapk) pathway. In addition, quercetin enhanced expression of tumor suppressor genes, including Pten, Tp53, and Msh2, and of cell cycle inhibitors, including Mutyh. Furthermore, dietary quercetin enhanced genes involved in phase I and II metabolism, including Fmo5, Ephx1, Ephx2, and Gpx2. Quercetin increased PPAR target genes, and concomitantly enhanced expression of genes involved in mitochondrial fatty acid (FA) degradation. Proteomics performed in the same samples revealed 33 affected proteins, of which four glycolysis enzymes and three heat shock proteins were decreased. A proteome-transcriptome comparison showed a low correlation, but both pointed out toward altered energy metabolism. In conclusion, transcriptomics combined with proteomics showed that dietary quercetin evoked changes contrary to those found in colorectal carcinogenesis. These tumor-protective mechanisms were associated with a shift in energy production pathways, pointing at decreased cytoplasmic glycolysis and toward increased mitochondrial FA degradation.
Combined carbon and hydrogen isotope fractionation investigations for elucidating benzene biodegradation pathways
Fischer, A. ; Herklotz, I. ; Herrmann, S. ; Thullner, M. ; Weelink, S.A.B. ; Stams, A.J.M. ; Richnow, H.H. ; Vogt, C. - \ 2008
Environmental Science and Technology 42 (2008)12. - ISSN 0013-936X - p. 4356 - 4363.
aromatic hydroxylation - anaerobic biodegradation - toluene 4-monooxygenase - aerobic biodegradation - pseudomonas-putida - stable carbon - degradation - transformation - enrichment - mechanism
Recently, combined carbon and hydrogen isotope fractionation investigations have emerged as a powerful tool for the characterization of reaction mechanisms relevant for the removal of organic pollutants. Here, we applied this approach in order to differentiate benzene biodegradation pathways under oxic and anoxic conditions in laboratory experiments. Carbon and hydrogen isotope fractionation of benzene was studied with four different aerobic strains using a monooxygenase or a dioxygenase for the initial benzene attack, a facultative anaerobic chlorate-reducing strain as well as a sulfate-reducing mixed culture. Carbon and hydrogen enrichment factors (epsilon(C), epsilon(H)) varied for the specific pathways and degradation conditions, respectively, so that from the individual enrichment factors only limited information could be obtained for the identification of benzene biodegradation pathways. However, using the slope derived from hydrogen vs carbon isotope discriminations or the ratio of hydrogen to carbon enrichment factors (lambda = deltaH/ deltaC approximately epsilon(H)/epsilon(C)), benzene degradation mechanisms could be distinguished. Although experimentally determined lambda values partially overlapped, ranges could be determined for different benzene biodegradation pathways. Specific lambda values were <2 for dihydroxylation, between 7 and 9 for monohydroxylation, and > 17 for anaerobic degradation. Moreover, variations in lambda values suggest that more than one reaction mechanism exists for monohydroxylation as well as for anaerobic benzene degradation under nitrate-reducing, sulfate-reducing, or methanogenic conditions. Our results show that the combined carbon and hydrogen isotope fractionation approach has potential to elucidate biodegradation pathways of pollutants in field and laboratory microcosm studies
Interactions between plant growth and soil nutrient cycling under elevated CO2: a meta-analysis
Graaff, M.A. de; Groenigen, K.J. van; Six, J. ; Hungate, B. ; Kessel, C. van - \ 2006
Global Change Biology 12 (2006)11. - ISSN 1354-1013 - p. 2077 - 2091.
atmospheric carbon-dioxide - nitrogen-fixation - organic-matter - microbial biomass - tallgrass prairie - responses - enrichment - dynamics - forest - respiration
free air carbon dioxide enrichment (FACE) and open top chamber (OTC) studies are valuable tools for evaluating the impact of elevated atmospheric CO2 on nutrient cycling in terrestrial ecosystems. Using meta-analytic techniques, we summarized the results of 117 studies on plant biomass production, soil organic matter dynamics and biological N-2 fixation in FACE and OTC experiments. The objective of the analysis was to determine whether elevated CO2 alters nutrient cycling between plants and soil and if so, what the implications are for soil carbon (C) sequestration. Elevated CO2 stimulated gross N immobilization by 22%, whereas gross and net N mineralization rates remained unaffected. In addition, the soil C : N ratio and microbial N contents increased under elevated CO2 by 3.8% and 5.8%, respectively. Microbial C contents and soil respiration increased by 7.1% and 17.7%, respectively. Despite the stimulation of microbial activity, soil C input still caused soil C contents to increase by 1.2% yr(-1). Namely, elevated CO2 stimulated overall above- and belowground plant biomass by 21.5% and 28.3%, respectively, thereby outweighing the increase in CO2 respiration. In addition, when comparing experiments under both low and high N availability, soil C contents (+2.2% yr(-1)) and above- and belowground plant growth (+20.1% and+33.7%) only increased under elevated CO2 in experiments receiving the high N treatments. Under low N availability, above- and belowground plant growth increased by only 8.8% and 14.6%, and soil C contents did not increase. Nitrogen fixation was stimulated by elevated CO2 only when additional nutrients were supplied. These results suggest that the main driver of soil C sequestration is soil C input through plant growth, which is strongly controlled by nutrient availability. In unfertilized ecosystems, microbial N immobilization enhances acclimation of plant growth to elevated CO2 in the long-term. Therefore, increased soil C input and soil C sequestration under elevated CO2 can only be sustained in the long-term when additional nutrients are supplied.
Roles of metal ion complexation and membrane permeability in the metal flux through lipophilic membranes. Labile complexes at permeation liquid membranes
Zhang, Z. ; Buffle, J. ; Leeuwen, H.P. van; Wojciechowski, K. - \ 2006
Analytical Chemistry 78 (2006)16. - ISSN 0003-2700 - p. 5693 - 5703.
copper speciation - natural-waters - trace-metals - fatty-acid - separation - voltammetry - system - enrichment - transport - as(iii)
The various physicochemical factors that influence the flux of carrier-transported metal ions through permeation liquid membranes (PLM) are studied systematically. Understanding PLM behavior is important (i) to optimize the application of PLM as metal speciation sensors in environmental media and (ii) because PLM may serve as bioanalogical devices that help to elucidate the environmental physicochemical processes occurring at the surface of biological membranes. Diffusion of free and complexed metal ions in solution, as well as diffusion of the metal carrier complex in the membrane, is considered. The respective roles of diffusion layer thickness, ligand concentration, complex stability, carrier concentration, and membrane thickness are studied experimentally in detail and compared with theory, using various labile complexes, namely, Pb(II)-diglycolate, Cu(II)-diglycolate, and Cu(II)-N-(2-carboxyphenyl)glycine. Conditions where either membrane diffusion or solution diffusion is rate limiting are clearly discriminated. It is shown in particular, that, by tuning the carrier concentration or membrane thickness, either the free metal ion concentration or the total labile metal species are measured. PLM can thus be used to determine whether models based on the free ion activity in solution (such as BLM or FIAM models) are applicable to metal uptake by microorganisms in a real natural medium
Effects of rearing and housing environment on behaviour and performance of pigs with different coping characteristics
Bolhuis, J.E. ; Schouten, W.G.P. ; Schrama, J.W. ; Wiegant, V.M. - \ 2006
Applied Animal Behaviour Science 101 (2006)1-2. - ISSN 0168-1591 - p. 68 - 85.
growing pigs - disintegration method - agonistic behavior - weaned pigs - pen size - enrichment - welfare - straw - productivity - provision
The availability of a rooting substrate may profoundly affect behaviour and welfare of pigs. Apart from their actual housing environment, also the conditions present in early life and individual characteristics may influence the behaviour of pigs. The present study investigated the relative importance of the housing environment during rearing and the actual housing environment on behaviour during the finishing phase, pathological lesions of the heart and stomach wall and weight gain in pigs with diverging coping characteristics. Pigs were reared either without a rooting substrate (barren, B) or in identical pens enriched with straw bedding (enriched, E). During the suckling period piglets were subjected to the Backtest. The Backtest classification of pigs is, to a certain extent, predictive of their coping style. Each piglet was restrained in supine position for 1 min and its resistance (i.e. the number of escape attempts) was scored. Sixty high-resisting (HR) and 60 low-resisting (LR) pigs were selected. Half of these pigs were from barren and the other half from enriched rearing environments. Pigs were housed in groups of six (three HR and three LR) after weaning. At 10 weeks of age, environmental conditions (B or E) were switched for half of the pens. Behaviour patterns of pigs during the finishing phase were largely determined by the actual presence or absence of straw bedding. Pigs that changed from enriched to barren pens (EB pigs), however, showed an increased inactivity beyond the inactivity levels of pigs with a barren rearing history (BB pigs). The impact of rearing history on chewing, manipulative and play behaviour in later life was larger for LR than for HR pigs. The availability of straw reduced the occurrence of gastric lesions in LR, but not in HR pigs. Feed intake tended to be lower in EB pens than in EE pens, but this was reflected in the growth rate of HR pigs only. HR-EE pigs showed a higher weight gain than HR-EB pigs. In conclusion, behaviour patterns of pigs were largely influenced by the actual (in)availability of straw. The influence of rearing history on behaviour, occurrence of gastric lesions and weight gain was smaller, and depended to some extent on coping characteristics (LR or HR) of the pigs under study
Mycorrhizal hyphal turnover as a dominant process for carbon input into soil organic matter
Godbold, D. ; Hoosbeek, M.R. ; Lukac, M. ; Francesca Cotrufo, M. ; Janssens, I.A. ; Ceulemans, R. ; Polle, A. ; Velthorst, E.J. ; Scarascia-Mugnozza, G. ; Angelis, P. de; Miglietta, F. ; Peressotti, A. - \ 2006
Plant and Soil 281 (2006)1-2. - ISSN 0032-079X - p. 15 - 24.
elevated atmospheric co2 - douglas-fir ecosystem - 1st growing-season - ectomycorrhizal fungi - forest ecosystems - external mycelium - root turnover - enrichment - nitrogen - patterns
The atmospheric concentration of CO2 is predicted to reach double current levels by 2075. Detritus from aboveground and belowground plant parts constitutes the primary source of C for soil organic matter (SOM), and accumulation of SOM in forests may provide a significant mechanism to mitigate increasing atmospheric CO2 concentrations. In a poplar (three species) plantation exposed to ambient (380 ppm) and elevated (580 ppm) atmospheric CO2 concentrations using a Free Air Carbon Dioxide Enrichment (FACE) system, the relative importance of leaf litter decomposition, fine root and fungal turnover for C incorporation into SOM was investigated. A technique using cores of soil in which a C-4 crop has been grown (delta C-13 -18.1 parts per thousand) inserted into the plantation and detritus from C-3 trees (delta C-13 -27 to -30 parts per thousand) was used to distinguish between old (native soil) and new (tree derived) soil C. In-growth cores using a fine mesh (39 mu m) to prevent in-growth of roots, but allow in-growth of fungal hyphae were used to assess contribution of fine roots and the mycorrhizal external mycelium to soil C during a period of three growing seasons (1999-2001). Across all species and treatments, the mycorrhizal external mycelium was the dominant pathway (62%) through which carbon entered the SOM pool, exceeding the input via leaf litter and fine root turnover. The input via the mycorrhizal external mycelium was not influenced by elevated CO2, but elevated atmospheric CO2 enhanced soil C inputs via fine root turnover. The turnover of the mycorrhizal external mycelium may be a fundamental mechanism for the transfer of root-derived C to SOM.
Long-term effects of elevated atmospheric CO2 on species composition and productivity of a southern African C4 dominated grassland in the vicinity of a CO2 exhalation.
Stock, W.D. ; Ludwig, F. ; Morrow, C. ; Midgley, G.F. ; Wand, S.J.E. ; Allsopp, N. ; Bell, T.L. - \ 2005
Plant Ecology 178 (2005)2. - ISSN 1385-0237 - p. 211 - 224.
tallgrass prairie ecosystem - soil carbon - biomass production - plant-communities - water relations - gas-exchange - growth - enrichment - responses - dynamics
We describe the long-term effects of a CO2 exhalation, created more than 70 years ago, on a natural C4 dominated sub-tropical grassland in terms of ecosystem structure and functioning. We tested whether long-term CO2 enrichment changes the competitive balance between plants with C3 and C4 photosynthetic pathways and how CO2 enrichment has affected species composition, plant growth responses, leaf properties and soil nutrient, carbon and water dynamics. Long-term effects of elevated CO2 on plant community composition and system processes in this sub-tropical grassland indicate very subtle changes in ecosystem functioning and no changes in species composition and dominance which could be ascribed to elevated CO2 alone. Species compositional data and soil ¿13C isotopic evidence suggest no detectable effect of CO2 enrichment on C3:C4 plant mixtures and individual species dominance. Contrary to many general predictions C3 grasses did not become more abundant and C3 shrubs and trees did not invade the site. No season length stimulation of plant growth was found even after 5 years of exposure to CO2 concentrations averaging 610 ¿mol mol-1. Leaf properties such as total N decreased in the C 3 but not C4 grass under elevated CO2 while total non-structural carbohydrate accumulation was not affected. Elevated CO2 possibly lead to increased end-of-season soil water contents and this result agrees with earlier studies despite the topographic water gradient being a confounding problem at our research site. Long-term CO2 enrichment also had little effect on soil carbon storage with no detectable changes in soil organic matter found. There were indications that potential soil respiration and N mineralization rates could be higher in soils close to the CO2 source. The conservative response of this grassland suggests that many of the reported effects of elevated CO2 on similar ecosystems could be short duration experimental artefacts that disappear under long-term elevated CO2 conditions
Effecten van brand op bodem en vegetatie in dennenbossen van voedselarme zandgronden bij Kootwijk
Kemmers, R.H. ; Dirkse, G.M. ; Hille, M.G. ; Mekkink, P. - \ 2005
Wageningen : Alterra (Alterra-rapport 1028) - 57
naaldbossen - bossen - verbranden - bodem - vegetatie - zandgronden - bosbranden - stikstof - verrijking - natuurgebieden - veluwe - gelderland - coniferous forests - forests - burning - soil - vegetation - sandy soils - forest fires - nitrogen - enrichment - natural areas
Door atmosferische stikstofdepositie zijn veel bossen van de arme zandgronden vermest en in hun verdere successie verstoord. In een voedselarm dennenbos op zandgrond is onderzocht of door brand de overmaat aan stikstof die in de strooisellaag ligt opgeslagen kan worden teruggedrongen en de bosontwikkeling kan worden teruggezet naar een voedselarme pionierfase. Het onderzoek werd uitgevoerd bij Kootwijk waar in 1995 een bosbrand woedde. De vegetatie- en bodemkundige toestand van voor de brand, één en negen jaar na de brand werd geanalyseerd. Een belangrijke conclusie is dat brand eerder tot een verrijking van de bodem leidt dan tot een verschraling. Door brand vindt een verplaatsing van elementen van ectorganische naar endorganische horizonten plaats. Weliswaar verdwijnt er in zijn totaliteit stikstof, maar direct na de brand is de bodem sterk verrijkt met kalium, ammonium en fosfaat en in zuurgraad gedaald. Bovendien wordt het beschikbaar gekomen ammonium door micro-organismen vastgelegd in organische stof wat daardoor een rijk karakter krijgt. Dit effect is negen jaar na de brand nog steeds aanwezig. Het laten staan van de necromassa na de brand, zoals in Kootwijk plaatsvond, draagt niet bij aan het terugzetten van de vegetatiesuccessie naar een initieel schraal stadium, maar wel aan de diversiteit van bodemeigenschappen
Personalities in pigs: Individual characteristics and coping with environmental challenges
Bolhuis, J.E. - \ 2004
Wageningen University. Promotor(en): V.M. Wiegant, co-promotor(en): W.G.P. Schouten; Johan Schrama. - [S.l.] : S.n. - ISBN 9085040620 - 176
varkens - persoonlijkheid - karakterisering - individuele kenmerken - stress - stressreactie - varkensstallen - adaptatie - diergedrag - dierenwelzijn - milieu - verrijking - immuniteitsreactie - dierfysiologie - pigs - personality - characterization - individual characteristics - stress response - pig housing - adaptation - animal behaviour - animal welfare - environment - enrichment - immune response - animal physiology
There are indications that pigs may have difficulty in adapting to the constraints of intensive housing conditions. Pigs show a wide variation in adaptive responses when exposed to the same stressful situation. Aim of this thesis was to investigate whether the behavioural coping responses of young piglets reflect and predict more general profiles of reactivity to challenges, often referred to as coping styles, under different rearing and housing conditions. For this purpose, pigs were characterized early in life as `high-resisting` (HR) or `low-resisting` (LR) on the basis of their resistance response in a so-called Backtest, in which they were manually restrained in supine position. The major part of the thesis focused on the interaction between these individual coping characteristics of pigs and their housing environment, which was either barren or enriched with straw bedding. The experiments described in this thesis show that HR pigs are more aggressive than LR pigs and less flexible in adapting their behaviour to environmental changes. As the two types of pig differed in response to the dopamine-agonist apomorphine, some initial evidence is provided for a neurochemical background of these behavioural differences. In addition, individual coping or personality characteristics of pigs were reflected in immune reactivity and in their home pen behaviour in barren and enriched environments. HR and LR pigs adapted differently to barren housing conditions. Moreover, individual characteristics modulated the effects of rearing and housing conditions on the behavioural response to novelty, immune reactivity, prevalence of gastric lesions and behavioural development. Remarkably, for almost all of the variables that were affected by housing environment, the impact was much larger for LR than for HR pigs. Thus, individual characteristics of pigs affect their performance in different environments and should be taken into account when studying the impact of housing on their behaviour and welfare. The knowledge of individual coping or personality characteristics could be extended and used for finding the optimal match between pigs and their social and physical environment in pig husbandry.
Nutrient limitation and nutrient-driven shifts in plant species composition in a species-rich fen meadow
Hoek, D. van der; Mierlo, A.J.E.M. van; Groenendael, J.M. van - \ 2004
Journal of Vegetation Science 15 (2004). - ISSN 1100-9233 - p. 389 - 396.
soortendiversiteit - plantenecologie - biomassa - inundatie - eutrofiëring - veengronden - stikstof - natuurreservaten - laagveengebieden - nederland - gelderland - species diversity - plant ecology - biomass - flooding - eutrophication - peat soils - nitrogen - nature reserves - fens - netherlands - mineral-nutrition - wild plants - vegetation - availability - enrichment - phosphorus - community - diversity - tundra
Question: We studied the development and persistence of the effects of nutrient pulses on biomass production and species composition in a fen meadow. Location: Nature reserve, central Netherlands, 5 m a.s.l. Methods: Single pulse fertilization with N and P in a factorial design on an undrained central and a drained margin site in a species-rich fen meadow (Cirsio dissecti-Molinietum). Biomass production and species composition were monitored during four years. Results: At the central site, N addition boosted biomass production, but only during one year. The species composition was not changed. P fertilization increased the biomass production and changed the species composition from a vegetation dominated by Carex panicea to a grassland community with abundant Holcus lanatus, but not before the second year. At the margin site, P fertilization changed the species composition in a similar way, but biomass production was not increased. N fertilization had no effect. At both sites the P induced shift in species composition persisted for four years although the P effect declined during the experiment. Conclusions: The biomass responses show that N was limiting in the central site. Another nutrient, besides N and P (probably K) must have been limiting in the marginal site. The fast decline of the N effect on biomass is ascribed to increased denitrification and biomass removal. The delay in the P effect on biomass and species composition and the persistence of the P effect on species composition are ascribed to fast immobilisation and subsequent slow release of fertilizer P in the peat soil. Recurrence of the P pulses is expected to cause permanent changes in species composition
Colony formation in Scenedesmus: a literature overview and further steps towards the chemical characterisation of the Daphnia kairomone
Holthoon, F.L. van; Beek, T.A. van; Lürling, M.F.L.L.W. ; Donk, E. van; Groot, Æ. de - \ 2003
Hydrobiologia 491 (2003)1-3. - ISSN 0018-8158 - p. 241 - 254.
diel vertical migration - morphological-changes - ecological role - fish - zooplankton - trimethylamine - induction - growth - enrichment - pheromone
Semiochemicals play an important role in interactions between living organisms in aquatic environments. Although the presence of chemical cues is confirmed in more and more systems, the chemical structures remain predominantly elusive. To create more accurate prey¿predator interaction models and to advance the research on chemical communication, it is essential to identify these compounds. A literature overview of cues involving Daphnia (either as producer or receiver) is given and the progress towards their isolation and structure elucidation is described. Most of the research so far has concentrated on the elucidation of kairomones produced by predators of Daphnia (especially Chaoborus and several species of fish). Although some progress has been made, these cues have not been isolated and identified yet. Additionally new results on the isolation and identification of the kairomone responsible for the colony formation in Scenedesmus using differential diagnosis and bioassay-directed fractionation of Daphnia exudates are presented. The importance of suitable and well performing bioassays herein cannot be underestimated. Some preliminary results with solid-phase extraction with C18 proved to be reproducible for extracting the active compound from Daphnia water, although it was not possible to get the biological activity into a single fraction. The cue was not extractable with an anion exchanger (SAX). Subjecting the extract to HPLC led to one active fraction
Verrijkte kooien voor leghennen in al zijn onderdelen
Fiks, T.G.C.M. ; Reuvekamp, B.F.J. ; Emous, R.A. van - \ 2003
Lelystad : Praktijkonderzoek Veehouderij (Praktijkboek / Animal Sciences Group 31) - 62
hennen - pluimveehouderij - pluimveehokken - kooien - verrijking - dierenwelzijn - hens - poultry farming - poultry housing - cages - enrichment - animal welfare
Het merendeel van de leghennen in de wereld wordt gehouden in batterijhuisvesting. Dit systeem heeft zich ontwikkeld vanuit een aantal wensen die aan de houderij van leghennen gesteld werd. Deze eisen lagen vooral op het gebied van economie, management, milieu, diergezondheid en productkwaliteit. Op deze punten scoort de legbatterij dan ook ruim voldoende. In de periode van de opkomst van de legbatterij als houderijsysteem was welzijn van dieren nog geen issue. Inmiddels wordt het welzijn van landbouwhuisdieren echter door diverse wetten en regels gewaarborgd. : :De in de EU-richtlijn van 1999 (EU, 1999a) genoemde verrijkte kooi werd ontwikkeld met het idee het goede van de batterij te behouden en de slechte kanten te verbeteren. In deze kooi zijn verschillende elementen ingebouwd, die het dier in staat stelt tot het vertonen van soortspecifiek gedrag. Hoewel de kostprijs van een ei uit de verrijkte kooi hoger is dan uit de batterij, biedt het systeem goede perspectieven met betrekking tot milieu, management, diergezondheid en productveiligheid. Voor het welzijn van het dier is het systeem een compromis tussen wat het dier verlangt en wat de pluimveehouder nodig heeft. In deze uitgave belichten we alle aspecten van verrijkte kooien, zowel vanuit de dierkant als vanuit de pluimveehouder. Het doel van deze uitgave is meerledig: : :1) Het geven van een samenvatting over al het verrichte onderzoek heen. : :2) Het op een toegankelijke wijze presenteren van alle aspecten, die van belang zijn bij verrijkte kooien. : :3) Het geven van tips waarop men moet letten bij de aanschaf en voor het management van verrijkte kooien.
Verrijkte kooien
Emous, R.A. van; Fiks, T.G.C.M. ; Reuvekamp, B.F.J. - \ 2003
Lelystad : Praktijkonderzoek Veehouderij (PraktijkRapport / Animal Sciences Group, Praktijkonderzoek : Pluimvee ) - 77
hennen - pluimveehokken - kooien - verrijking - snavelkappen - zitstokken (vogels) - legresultaten - verenpikken - kannibalisme - belichting - dierenwelzijn - hens - poultry housing - cages - enrichment - debeaking - perches - laying performance - feather pecking - cannibalism - illumination - animal welfare
Ruim 75 % van de leghennen in Nederland wordt in batterijkooien gehouden. Deze kooi werd vele jaren gezien als het ideale houderijsysteem voor leghennen. Vanuit ethologisch gezichtspunt is het houden van legkippen in batterijsystemen echter een flinke beperking voor de dieren. Om deze reden is de batterij in een kwaad daglicht komen te staan en is vanuit de maatschappij de roep om welzijnsvriendelijkere huisvestingssystemen steeds sterker geworden. Men houdt steeds meer leghennen in alternatieve systemen als scharrel en volière, waar de dieren de beschikking hebben over een ruime hoeveelheid strooisel. Verder zijn er legnesten en zitstokken in de systemen ingebouwd. Volière en scharrel zijn voor de kleinere bedrijven goede alternatieven. Voor grote bedrijven zijn ze minder aantrekkelijk, omdat ze minder voorspelbaar in arbeid zijn, storingsgevoeliger in productie, hogere milieubelasting (NH3 en stof) hebben en een hogere kostprijs van de eieren. Tot eind jaren 90 verliep de omschakeling naar dit soort systemen erg langzaam, maar nadat de EU-richtlijn voor het houden van leghennen in 1999 van kracht werd, is in Nederland veel geïnvesteerd in alternatieve systemen. De ontwikkelingen naar welzijnsvriendelijke houderij van leghennen is geen Nederlandse aangelegenheid. Dit bleek uit de wijziging in de Europese regelgeving, die in 1999 is doorgevoerd. Deze legt de huisvesting van leghennen in kooien aan banden en verbiedt het huidige batterijsysteem per 1 januari 2012. Vanaf die datum is alleen de huisvesting in alternatieven (scharrel/volière) of in verrijkte kooisystemen toegestaan. Het Nederlandse bedrijfsleven heeft de roep naar welzijnsvriendelijkere huisvestingssystemen voor leghennen onder anderen vertaald naar een opdracht voor het Praktijkonderzoek om de verrijkte kooisystemen te onderzoeken en te ontwikkelen. Als uitgangspunt voor de systemen gold dat ze gebaseerd moesten zijn op het kooiprincipe en minimaal moesten voldoen aan de eisen zoals die in de EU-richtlijn van juli 1999 zijn geformuleerd. Dit onderzoek heeft vorm gekregen in het Project Verrijkte kooien voor leghennen, ook wel kortweg bekend onder de naam Project 1030 (het aanvankelijke interne projectnummer). Gezien de korte termijn waarop bedrijfsleven en politiek informatie moesten hebben over verrijkte kooisystemen, is gekozen voor een proefopzet, waarbij veel verschillende systemen zijn getest. Het Ingrepenbesluit bepaalt dat in nieuwe houderijsystemen die men na 1 september 2001 in gebruik neemt geen dieren mogen worden opgezet die een snavelbehandeling hebben ondergaan. Voor alternatieve houderijsystemen is echter een uitstel van 5 jaar verleend. Dit geldt niet voor kooisystemen (dus ook verrijkte kooien), omdat de kleinere groepsgrootte verenpikkerij en kannibalisme daar beter beheersbaar maakt. Hoewel de groepen dieren in kooien kleiner zijn dan in alternatieve houderijsystemen moet men echter wel rekening houden met dit potentiële pikkerijprobleem. Dit gegeven was aanleiding om extra aandacht te besteden aan het houden van ongekapte hennen en het voorkómen van verenpikkerij en kannibalisme. Het toepassen van verschillende verlichtingssystemen is daarom onderwerp van onderzoek geweest. Het eerste en belangrijkste doel van het onderzoek aan verrijkte kooisystemen was het testen ervan en het opdoen van ervaringen met verschillende ontwerpen. Ook binnen elk kooisysteem zijn diverse varianten getest om te zien welke het beste functioneert. Daarbij is ervaring opgedaan die breder gaat dan alleen dat bewuste systeem, zodat ook algemenere conclusies mogelijk zijn. De hoofdvraag van het onderzoek was telkens: hoe functioneert een systeem. De punten waarnaar we keken zijn: Wat zijn de productieresultaten? Hoe is de eikwaliteit? Wat is de uitval en in het bijzonder de uitval door pikkerij? Hoe functioneren het legnest, de strooiselruimte, de zitstokken en het nagelgarnituur? Hoe gedragen de dieren zich: gebruiken ze het strooisel, het legnest en d
Effect van verrijking omgeving en beperking weidegang op wroetschade door zeugen
Mheen, H. van der; Spoolder, H.A.M. - \ 2003
Lelystad : Praktijkonderzoek Veehouderij (PraktijkRapport / Praktijkonderzoek Veehouderij : Varkens ) - 21
zeugen - varkenshouderij - rantsoenbeweiding - weiden - schade - verrijking - mineralen - stikstof - diergedrag - biologische landbouw - sows - pig farming - controlled grazing - pastures - damage - enrichment - minerals - nitrogen - animal behaviour - organic farming
Veel biologische varkenshouders weiden hun drachtige en guste zeugen. Het in stand houden van de graszode is door het wroeten van varkens echter niet vanzelfsprekend, maar wel gewenst. Zonder gras valt er weinig meer te grazen en valt het voordeel vanextra voeropname weg. Daarnaast is de uitspoeling van mineralen op kale grond veel groter dan op grasland.
Model simulation of effects of changes in climate and atmospheric CO2 and O3 on tuber yield potential of potato (cv Bintje) in the European Union
Wolf, J. ; Oijen, M. van - \ 2003
Agriculture, Ecosystems and Environment 94 (2003). - ISSN 0167-8809 - p. 141 - 157.
triticum-aestivum l - open-top chambers - elevated co2 - spring wheat - photosynthetic apparatus - ozone - growth - acclimation - enrichment - responses
A simple simulation model for potato growth was improved on the basis of the experimental results from the EU-project CHIP. To test if the model works well for the different CO2 and O3 treatments under a range of environmental conditions in the EU, the experimental results from all treatments at the sites within this project were compared with the simulated results. A detailed analysis was done first for Rapolano, Italy and Tervuren, Belgium. This showed that in general the time courses of the observed CO2 and O3 effects on tuber yields at Tervuren and of the CO2 effect at Rapolano were simulated well. Next, crop variables as observed at the final harvest in all experiments within this project were compared with the simulated results. This showed that the total radiation interception was simulated well. Radiation use efficiency (RUE), however, was simulated well for only half of the sites. As a consequence, total biomass and tuber yields could only be simulated well for all sites, if photosynthetic parameters in the model were calibrated separately for half of the sites. These and other difficulties in the development and testing of the potato model on the basis of the CHIP experimental data set were discussed.
Huisvesting en verzorging van vleeskuikenouderdieren zonder ingrepen
Haar, J.W. van der; Voorst, A. van; Middelkoop, J.H. van; Lourens, A. - \ 2002
Lelystad : Praktijkonderzoek Veehouderij (PraktijkRapport. Pluimvee 3) - 23
vleeskuikens - pluimveehokken - dierenwelzijn - milieu - verrijking - vleeskuikenouderdieren - broilers - poultry housing - animal welfare - environment - enrichment - broiler breeders
Door het Ingrepenbesluit zijn ingrepen bij vleeskuikenouderdieren op termijn verboden. Praktijkonderzoek Veehouderij (voorheen Praktijkonderzoek Pluimveehouderij) onderzoekt daarom sinds 1998 het effect van het achterwege laten van ingrepen bij vleeskuikenouderdieren in relatie tot huisvesting en verzorging. Dit rapport beschrijft de resultaten van de laatste (derde) proef. Al eerder verschenen de bevindingen over de effecten van weglaten van ingrepen bij vleeskuikenouderdieren op gedrag, veer- en huidbeschadigingen, uitval en technische resultaten.
Strooiselverstrekking in verrijkte kooien
Fiks-van Niekerk, Th. ; Reuvekamp, B. ; Emous, R. van - \ 2001
Praktijkonderzoek. Pluimvee 15 (2001)1. - ISSN 1570-2537 - p. 7 - 9.
hennen - vrouwelijke dieren - huisvesting, dieren - strooisel - organisch bodemmateriaal - kooien - verrijking - eu regelingen - richtlijnen (guidelines) - stof - bedrijfshygiëne - hens - female animals - animal housing - litter (plant) - soil organic matter - cages - enrichment - eu regulations - guidelines - dust - industrial hygiene
De nieuwe EU-richtlijn voor het houden van leghennen stelt strooisel in verrijkte kooien op termijn verplicht. Hoewel er voldoende technieken zijn om dit te kunnen realiseren, blijkt de keuze van de juiste technieken en materialen van groot belang. Indit artikel de laatste stand van zaken.
Restoration of species-rich grasslands on reconstructed river dikes
Liebrand, C.I.J.M. - \ 1999
Agricultural University. Promotor(en): K.V. Sýkora. - S.l. : Liebrand - ISBN 9789058080318 - 217
graslanden - vegetatiebeheer - botanische samenstelling - soortendiversiteit - plantensuccessie - rivieren - herstel - verrijking - dijken - nederland - grasslands - vegetation management - botanical composition - species diversity - plant succession - rivers - rehabilitation - enrichment - dykes - netherlands
<p>Up until 30 years ago an extensive, flower-rich grassland vegetation containing many species rare in the Netherlands used to be common on Dutch river dikes. However, the deterioration of the flora on dikes was already being reported at the end of the 1960s. At that time too, ecologists warned that the planned reinforcement of the dikes along the Rhine, Waal, Lek and IJssel would adversely affect the flora. Their gloomy forecasts have proved to be correct. Between 1968 and 1992 as much as 89% of the locations with a dry floodplain grassland vegetation in the Netherlands disappeared.</p><p>In 1992 the vegetation of over 90% of the river dikes consisted of species-poor grassland on which sheep graze, and rough vegetation mown for hay. Only about 7% of the surface area of the river dikes was covered by relatively species-rich grasslands belonging to the phyto-sociological syntaxa <em>Arrhena-theretum elatioris</em> and <em>Lolio-Cynosuretum</em> , both belonging to the <em>Arrhenatherion elatioris</em> . Only 1% was covered by the typical species-rich dry grassland <em>Medicagini-Avenetum</em> . The last remnants of these grasslands are in imminent danger of disappearing.</p><p>The deterioration in the semi-natural vegetation has mainly been caused by the fact that the slopes of the dikes are increasingly being used agriculturally (fertilization, overgrazing, use of herbi-cides) but also because ecological features were insufficiently taken into account while reinforcing the dikes. In 1984 a research project was started to ascertain the optimum structure and growing con-ditions for the grass cover on river dikes (Sýkora & Liebrand, 1987; van der Zee, 1992). The next step was to test the feasibility of the ecological engineering measures proposed in the above mentioned projects empirically.</p><p>In the research project described in this thesis the core questions were therefore whether the valuable, species-rich vegetation on the dikes can return after reinforcement works, and, if so, what are the pre-conditions for this during and after the reinforcement. The research was carried out on the basis of data of 209 permanent quadrats divided over 125 trial fields. Each permanent quadrat has its own specific method of reconstruction, sowing and management.</p><p>Ninety-eight percent of the plant species found before reconstruction, reappeared after recon-struction. Most species reappeared on the replaced former top layer. Only a few (rare) species did not reappear but were still present in the unmodified zone. Most relatively rare species occur only in low numbers and consequently they are still at risk of disappearing, especially if no proper management is applied. Because of this, a spared zone seems to be the best guarantee for the conservation of the plant species after the reconstruction.</p><p>In the period 1987-1994 9 plant communities were distinguished within the vegetation of the experimental river dike. They can be classified as follows on the basis of method of reconstruction, management and successional stage: the <em>Arrhenatheretum</em> with <em>Peucedanum carvifolia</em> and <em>Rumex thyrsiflorus</em> (I) is typical for the spared zone, the species-poor <em>Arrhenatheretum</em> with <em>Urtica dioica</em> and <em>Valeriana officinalis</em> (II) is a rough vegetation resulting from bad management, the <em>Arrhenatheretum</em> with <em>Leucanthemum vulgare</em> and <em>Lysimachia nummularia</em> (III) is a species-rich grassland occurring under good and moderate management practices on replaced sods and replaced topsoil, the <em>Arrhenatheretum</em> with dominance of <em>Alopecurus pratensis</em> (V) is an intermediate vegetation which will develop further, either into a hayfield vegetation or into a pasture vegetation, depending on the management applied, the <em>Lolio-Cynosuretum</em> with <em>Crepis capillaris</em> and <em>Ranunculus repens</em> (VI) is a grassland vegetation strongly influenced by grazing and the <em>Arrhenatheretum</em> with <em>Leucanthemum vulgare</em> and <em>Trifolium pratense</em> (IV), the association fragment of the <em>Arrhenatheretum</em> with <em>Phleum pratense</em> and <em>Ranunculus repens</em> (VII), the fragmentary community with <em>Matricaria maritima</em> and <em>Plantago major</em> [ <em>Arrhenatherion/Chenopodion</em> ] (VIII) and the fragmentary community with <em>Capsella bursa-pastoris</em> and <em>Poa annua</em> [ <em>Eu-Polygono-Chenopodion</em> ] (IX) are pioneer stages, which had wholly or almost disappeared in 1994.</p><p>The best way to assure maintenance of species-rich grassland vegetation on reconstructed river dikes is to spare a strip or zone of this vegetation during the reconstruction. Species disperse from here to other parts of the dike and the redevelopment of the vegetation is stimulated. To ensure opti-mal results, the soil composition of those new parts should resemble the soil composition of the spared zone as much as possible. If it is not possible to save part of the original vegetation, the upper soil layer can be set aside in the form of turves or as topsoil and can be replaced as the new topsoil after the reconstruction. Replacing the original topsoil after the reinforcement provides a topsoil of similar composition to that before the reinforcement. Besides, the redevelopment of species-rich grasslands is promoted by previously occurring species re-establishing from the propagules present in the replaced topsoil. The application of the under layer as the new top layer and the use of imported clay as the new top layer both prevent a quick restoration of botanically valuable, semi-natural, species-rich grasslands. Propagules are very rare or even absent.</p><p>The seed mixtures applied influence the development of succession. Application of seed mixtures gathered locally accelerates succession. Seed mixtures containing a considerable proportion of <em>Lolium perenne</em> seeds are unsuitable, as the redevelopment is retarded, especially when applied in the high densities (such as 70 kg.ha <sup>-1</SUP>) which used to be common. Sowing an annual grass species like <em>Lolium multiflorum</em> or the standard seed mixture D1 in a low density of 20 to 25 kg.ha <sup>-1</SUP>seemed not to retard the development of a species-rich vegetation.</p><p>In the first years after reconstruction the influence of the methods of reconstruction and the seed mixtures applied appears to be preponderant. In the first years the structure of the vegetation is quite open and the competition between species is low. When the vegetation closes, competition increases. Subsequently, management of the vegetation can be used as an important means to regulate competition and, consequently, species composition. A species-rich vegetation only develops when managed properly.</p><p>On the basis of erosion resistance features like openness of the sward, ground cover, root density and shear resistance, the best management practices appear to be grazing in June in combination with hay-making in September, hay-making in June in combination with grazing in September and hay-making twice a year. In this respect, grazing twice a year, grazing during the whole season, hay-making in September and hay-making in June in combination with mulching in September are moderately effective. Hay-making in June, mulching twice a year, hay-making once every two year, burning and no management are bad management practices.</p><p>On the basis of ecological features such as species-richness and number and proportion of rare species, the best management is hay-making twice a year. In this respect, hay-making in June in combination with mulching in September, hay-making in June, hay-making in September and hay-making in June in combination with grazing in September are moderately effective. The other grazing practices, mulching twice a year, hay-making once every two year, burning and no management are bad management practices.</p>
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