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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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    Biological mechanisms discriminating growth rate and adult body weight phenotypes in two Chinese indigenous chicken breeds
    Dou, Tengfei ; Zhao, Sumei ; Rong, Hua ; Gu, Dahai ; Li, Qihua ; Huang, Ying ; Xu, Zhiqiang ; Chu, Xiaohui ; Tao, Linli ; Liu, Lixian ; Ge, Changrong ; Pas, M.F.W. te; Jia, Junjing - \ 2017
    growth rate - chicken breeds - Gallus gallus - breast muscle - liver - microarray - metabolic differences - biological mechanisms
    Background Intensive selection has resulted in increased growth rates and muscularity in broiler chickens, in addition to adverse effects, including delayed organ development, sudden death syndrome, and altered metabolic rates. The biological mechanisms underlying selection responses remain largely unknown. Non-artificially-selected indigenous Chinese chicken breeds display a wide variety of phenotypes, including differential growth rate, body weight, and muscularity. The Wuding chicken breed is a fast growing large chicken breed, and the Daweishan mini chicken breed is a slow growing small chicken breed. Together they form an ideal model system to study the biological mechanisms underlying broiler chicken selection responses in a natural system. The objective of this study was to study the biological mechanisms underlying differential phenotypes between the two breeds in muscle and liver tissues, and relate these to the growth rate and body development phenotypes of the two breeds. Results The muscle tissue in the Wuding breed showed higher expression of muscle development genes than muscle tissue in the Daweishan chicken breed. This expression was accompanied by higher expression of acute inflammatory response genes in Wuding chicken than in Daweishan chicken. The muscle tissue of the Daweishan mini chicken breed showed higher expression of genes involved in several metabolic mechanisms including endoplasmic reticulum, protein and lipid metabolism, energy metabolism, as well as specific immune traits than in the Wuding chicken. The liver tissue showed fewer differences between the two breeds. Genes displaying higher expression in the Wuding breed than in the Daweishan breed were not associated with a specific gene network or biological mechanism. Genes highly expressed in the Daweishan mini chicken breed compared to the Wuding breed were enriched for protein metabolism, ABC receptors, signal transduction, and IL6-related mechanisms. Conclusions We conclude that faster growth rates and larger body size are related to increased expression of genes involved in muscle development and immune response in muscle, while slower growth rates and smaller body size are related to increased general cellular metabolism. The liver of the Daweishan breed displayed increased expression of metabolic genes.
    Matching breeding goals with farming systems to enhance the sustainability of fish farming
    Besson, Mathieu - \ 2017
    Wageningen University. Promotor(en): Imke de Boer; Hans Komen, co-promotor(en): M. Vandeputte. - Wageningen : Wageningen University - ISBN 9789463430067 - 201
    fish culture - sustainability - animal production - farming systems - models - feed conversion - breeding - growth rate - feed conversion efficiency - animal welfare - visteelt - duurzaamheid (sustainability) - dierlijke productie - bedrijfssystemen - modellen - voederconversie - veredelen - groeitempo - voederconversievermogen - dierenwelzijn

    Fish farming is growing but is also facing challenges regarding economic viability and environmental sustainability. Selective breeding could enhance the sustainability of fish farming by changing animal performances. Thus, our aim was to develop sustainable breeding goals by using economic (EV) or environmental values (ENV) to weigh the traits to improve. EV and ENV represent the economic and environmental impacts of improving a trait. They were calculated using a bioeconomic model combined with a life cycle assessment. We showed that the EV and ENV of traits change with the factor constraining the production of the farm. It suggests that breeding goals should be finely tuned according to the limiting factor to maximize economic or environmental responses. In addition, we showed that improving feed conversion ratio is a major trait to improve because it always increases profit and decreases environmental impacts. We conclude that it is possible to develop breeding programs enhancing the sustainability of fish farming by improving the right trait in the right production system.

    Data from: Direct and indirect genetic effects in life history traits of flour beetles (Tribolium castaneum)
    Ellen, E.D. ; Peeters, K.L.M. ; Verhoeven, M.T.W. ; Gols, R. ; Harvey, J.A. ; Wade, M.J. ; Dicke, M. ; Bijma, P. - \ 2015
    pupal boidy mass - development time - growth rate - IGE - social interactions - Tribolium castaneum
    Indirect genetic effects (IGEs) are the basis of social interactions among conspecifics, and can affect genetic variation of non-social as well as social traits. We used flour beetles (Tribolium castaneum) of two phenotypically distinguishable populations to estimate genetic (co)variances and the effect of IGEs on three life-history traits: development time (DT), growth rate (GR), and pupal body mass (BM). We found that GR was strongly affected by social environment with IGEs accounting for 18% of the heritable variation. We also discovered a sex-specific social effect: male ratio in a group significantly affected both GR and BM. That is, beetles grew larger and faster in male-biased social environments. Such sex-specific IGEs have not previously been demonstrated in a non-social insect. Our results show that beetles that achieve a higher BM do so via a slower GR in response to social environment. Existing models of evolution in age-structured or stage-structured populations do not account for IGEs of social cohorts. It is likely that such IGEs have played a key role in the evolution of developmental plasticity shown by Tenebrionid larvae in response to density. Our results document an important source of genetic variation for GR, often overlooked in life-history theory.
    Genetic and phenotypic parameter estimates for growth traits of Hainan Black goat in southern China
    Zhou, Han Lin ; Gu, Li Hong ; Sun, Yanyan ; Xu, Tie Shan ; Rong, Guang - \ 2015
    Animal Production Science 55 (2015)4. - ISSN 1836-0939 - p. 447 - 453.
    bodyweight - genetic correlation - growth rate - heritability

    Genetic improvement of the growth of Hainan Black goats is a major concern as the breed is an important meat-type goat raised in southern China. To estimate genetic and phenotypic parameters for growth traits for this breed, a population of 1354 Hainan Black goats born and maintained at the Hainan Black Goat Breeding Farm from 2007 to 2011 was used. Heritabilities and phenotypic and genetic correlations for bodyweights (BWs) at birth and at 2, 4, 6, 8, 10 and 12 months of age (denoted as BW0, BW2, BW4, BW6, BW8, BW10 and BW12, respectively) and average daily weight gains (ADGs) from birth to 2 months, from 2 to 6 months, and from 6 to 12 months (denoted as ADG0-2, ADG2-6 and ADG6-12, respectively) were estimated using an animal model, with and without a permanent maternal environmental effect fitted as a random effect. Litter size, kidding year, birth season and sex, as well as their interactions, were investigated as fixed effects. Likelihood ratio testing indicated that the model with a permanent maternal environmental effect was better than that without a permanent maternal environmental effect for all traits. The direct additive heritability for BW and ADG ranged from 0.17 (ADG6-12) to 0.45 (BW0), indicating that growth traits of Hainan Black goats can be improved by phenotypic selection. Maternal permanent environmental variance was also estimated and varied from 0.08 (BW6) to 0.27 (BW10). The genetic and phenotypic correlations among ADG traits were positive and relatively low. However, the positive and relatively high genetic and phenotypic correlations among BW traits indicated that breeding programs are able to use selection at early ages to improve BW traits.

    Establishing the link between habitat-selection and animal population dynamics
    Matthiopoulos, J. ; Fieberg, J. ; Aarts, G.M. ; Beyer, H.L. ; Morales, J.M. ; Haydon, D.T. - \ 2015
    Ecological Monographs 85 (2015)3. - ISSN 0012-9615 - p. 413 - 436.
    species distribution models - point process models - resource selection - functional-responses - growth rate - large herbivores - climate-change - niche breadth - fitness - ecology
    Although classical ecological theory (e.g., on ideal free consumers) recognizes the potential effect of population density on the spatial distribution of animals, empirical species distribution models assume that species–habitat relationships remain unchanged across a range of population sizes. Conversely, even though ecological models and experiments have demonstrated the importance of spatial heterogeneity for the rate of population change, we still have no practical method for making the connection between the makeup of real environments, the expected distribution and fitness of their occupants, and the long-term implications of fitness for population growth. Here, we synthesize several conceptual advances into a mathematical framework using a measure of fitness to link habitat availability/selection to (density-dependent) population growth in mobile animal species. A key feature of this approach is that it distinguishes between apparent habitat suitability and the true, underlying contribution of a habitat to fitness, allowing the statistical coefficients of both to be estimated from multiple observation instances of the species in different environments and stages of numerical growth. Hence, it leverages data from both historical population time series and snapshots of species distribution to predict population performance under environmental change. We propose this framework as a foundation for building more realistic connections between a population's use of space and its subsequent dynamics (and hence a contribution to the ongoing efforts to estimate a species' critical habitat and fundamental niche). We therefore detail its associated definitions and simplifying assumptions, because they point to the framework's future extensions. We show how the model can be fit to data on species distributions and population dynamics, using standard statistical methods, and we illustrate its application with an individual-based simulation. When contrasted with nonspatial population models, our approach is better at fitting and predicting population growth rates and carrying capacities. Our approach can be generalized to include a diverse range of biological considerations. We discuss these possible extensions and applications to real data.
    A tale too long for a tail too short? : identification of characteristics in pigs related to tail biting and other oral manipulations directed at conspecifics
    Ursinus, W.W. - \ 2014
    Wageningen University. Promotor(en): Bas Kemp, co-promotor(en): Liesbeth Bolhuis; Kees van Reenen. - Wageningen : Wageningen University - ISBN 9789462570023 - 248
    varkens - staartbijten - gedragsstoornissen - karakteristieken - bangheid - dierenwelzijn - genetische effecten - groeitempo - omgevingsverrijking - diergedrag - dierfysiologie - pigs - tail biting - behaviour disorders - characteristics - fearfulness - animal welfare - genetic effects - growth rate - environmental enrichment - animal behaviour - animal physiology

    Ursinus, W.W. (2014). A tale too long for a tail too short? Identification of

    characteristics in pigs related to tail biting and other oral manipulations directed

    at conspecifics. PhD thesis, Wageningen University, The Netherlands.

    Tail biting in pigs, i.e. the chewing on and biting in tails of conspecifics, is a

    multifactorial problem leading to impaired pig welfare and health and economic

    losses in pig farming. In many countries tail docking is used as a preventive

    measure, but there is increased societal concern about this practice. Therefore,

    there is an urgent need to understand, prevent, and reduce tail biting and other

    damaging behaviours directed at pen mates. The main aim of this thesis was to

    identify biological characteristics of barren and enriched housed pigs that relate

    to their tendency to develop these damaging oral manipulative behaviours. Tail

    biting started already early in life and pigs that displayed tail biting post-weaning

    seemed to stem from litters in which tail biting behaviour was already present. The

    onset of tail biting behaviour was different for individual pigs, and many pigs were

    not consistently tail biters throughout different phases of life. It was difficult to

    predict which pigs would develop tail biting based on their individual behaviour.

    Groups of pigs with tail biting problems were, however, more easy to identify by

    increased activity, and increased levels of pig and pen-directed oral manipulative

    behaviours. Subjecting pigs to an individual behavioural test showed that tail

    biters may be more fearful. Fearfulness in pigs appeared related to measures

    of the brain and blood serotonergic system. Moreover, measures of the blood

    serotonergic system seemed temporarily altered in tail biting pigs mainly during

    the phase of life in which they displayed this behaviour. Additionally, (tail) biting

    behaviour may be associated with higher (phenotypic and genotypic) production,

    such as higher growth. Growth of individual pigs can be affected by the other

    pigs in a pen. The heritable effect of one pig on the growth of another group

    member is referred to as an indirect genetic effect. Pigs with a relatively negative

    indirect genetic effect for growth displayed more biting behaviours, caused more

    tail damage and destroyed more of the available jute sacks. The presence of strawbedding

    or jute sacks as enrichment materials for rooting and chewing largely

    reduced damaging biting behaviours and, consequently, tail damage. Pigs that

    still develop tail biting behaviour in an enriched environment likely do so due to

    a (temporary) physiological problem, whereas in barren housed pigs the lack of

    suitable rooting and chewing material plays a large role. Tail biting behaviour

    in pigs thus seems to be caused by a variety of temporary states and more

    stable traits that influence their motivation to display foraging and exploratory

    behaviours. Therefore, the tale of (tail) biting behaviours in pigs needs a better

    understanding of underlying physiological processes. Preventing and reducing

    damaging biting behaviours in pigs requires a joint effort of science, industry

    and society to optimize housing conditions, feeding, management and breeding

    of pigs.

    Physiological and molecular adaptations of Lactococcus lactis to near-zero growth conditions
    Ercan, O. - \ 2014
    Wageningen University. Promotor(en): Michiel Kleerebezem, co-promotor(en): Eddy Smid. - Wageningen : Wageningen University - ISBN 9789462570719 - 206
    lactococcus lactis - adaptatiefysiologie - voedselmicrobiologie - groeitempo - groeispanning - transcriptomica - metabolomica - lactococcus lactis - adaptation physiology - food microbiology - growth rate - growth stress - transcriptomics - metabolomics

    Lactococcus lactis is an important lactic acid bacteria (LAB) species that is used for the manufacture of dairy products, such as cheese, buttermilk, and other fermented products. The predominant function of this bacterium in dairy fermentation is the production of lactic acid, as its major fermentation end-product that contributes to preservation and microbial safety of the product. Moreover, L. lactis is frequently encountered in natural ecosystems such as in (rotting) plant material.

    Due to restricted energy source availability, natural microbial communities commonly live in a situation that can be characterized as ‘hunger’, which is different from strict nutrient-starvation. As a consequence, environmental microbes commonly grow at very low-growth rates as compared to laboratory cultures. Analogously, microorganisms can experience such nutrient-poor conditions in diverse industrial fermentation applications. For example, LAB encounter extreme low or no energy source availability during the extended ripening process of cheeses or dry sausages, which can take months. Despite these harsh environmental conditions, many LAB are able to remain viable in these processes for months and sustain a low-level metabolic activity, which plays an important role in their contribution to flavor and aroma formation in the product matrix.

    In this thesis, the quantitative physiology of L. lactis at near-zero specific growth rates was studies, employing both metabolic and genome-wide transcriptome studies in an experimental set-up of carbon-limited retentostat cultivation. Chapter 2 describes how retentostat cultivation enables uncoupling of growth and non-growth related processes in L. lactis, allowing the quantitative analysis of the physiological adaptations of this bacterium to near-zero growth rates. In chapter 3, transcriptome and metabolome analyses were integrated to understand the molecular adaptation of L. lactis to near-zero specific growth rate, and expand the studies in chapter 2 towards gene regulations patterns that play a profound role in zero-growth adaptation. Chapter 4 describes the enhanced robustness to several stress conditions of L. lactis after its adaptation to extremely low-specific growth rate by carbon-limited retentostat cultivation. In this chapter correlations were modelled that quantitatively and accurately describe the relationships between growth-rate, stress-robustness, and stress-gene expression levels, revealing correlation coefficients for each of the varieties involved. Chapter 5 evaluates the distinction between the transcriptome responses to extended carbon-limited growth and severe starvation conditions, where the latter condition was elicited by switching off the medium supply of the retentostat cultures described in chapter 1. Chapter 6 highlights the comparison of the physiological and molecular adaptations of industrially important microorganisms towards carbon-limited retentostat conditions. In conclusion, this thesis describes the quantitative physiological, metabolic, and genome-wide transcriptional adaptations of L. lactis at near-zero specific growth rates induced by carbon source limited retentostat cultivation, and compares these molecular adaptations to those elicited by strict carbon-starvation conditions.

    Sociable swine : indirect genetic effects on growth rate and their effect on behaviour and production of pigs in different environments
    Camerlink, I. - \ 2014
    Wageningen University. Promotor(en): Johan van Arendonk; Bas Kemp, co-promotor(en): Liesbeth Bolhuis; Piter Bijma. - Wageningen : Wageningen University - ISBN 9789461739551 - 231
    varkens - sociaal gedrag - genetische effecten - groeitempo - diergedrag - agressief gedrag - sociaal milieu - dierlijke productie - selectief fokken - varkenshouderij - pigs - social behaviour - genetic effects - growth rate - animal behaviour - aggressive behaviour - social environment - animal production - selective breeding - pig farming

    Social interactions between pigs can influence their health, welfare, and productivity. The effects of social interactions on individuals are partly genetic, and this genetic effect is known as an Indirect Genetic Effect. IGEs are thus the heritable effects of an individual on the trait values of its social partners, e.g. group mates. Previous research has identified IGE for production traits, which suggests that selection for IGE may contribute to selection response. However, validation through selection experiments is required.

    The objectives of this thesis were a) to determine the consequences of selection for ‘IGE on growth rate’ (IGEg) for production traits and behaviour of pigs, and b) to study possible mechanisms underlying IGEg in pigs. First, the relationship between pig behaviour and growth rate was studied in several trials. This showed that oral manipulative behaviours directed at pen mates, such as tail- and ear biting and chewing, can reduce growth rate of the victims, whereas receiving social nosing may enhance growth rate. Second, a one-generation selection experiment was conducted in pigs. Sires (n= 24) and dams (n= 64) were selected to create a high vs. low contrast for IGEg in the offspring (n= 480). The contrast was 14 g average daily gain (ADG). Offspring were studied in a 2×2 arrangement with IGEg (high vs. low) and housing conditions (conventional vs. enriched with straw bedding) to examine genotype × environment (GxE) interactions. Selection did not alter production traits, including ADG. Behaviour showed consistent changes, whereby high IGEg pigs showed less biting behaviour towards group mates and objects. High and low IGEg pigs did not differ in aggression or body lesions during 24-h regrouping with unfamiliar pigs. They did, however, differ in aggression towards their own group members when they were reunited after the temporary regrouping test. In combination with other tests and observations, this might indicate that high IGEg pigs are less fearful or less stress sensitive than low IGEg pigs. There were no G×E interactions, but enrichment had a positive effect on behaviour which was additive to that of selection. Despite the lack of response in ADG, genetic selection for IGEg and enriched housing conditions improved the behaviour and welfare of pigs.

    Effects of available phosphorus (aP), calcium/aP ratio, and growth rate on P deposition, P digestibility, performance and leg quality in broilers
    Krimpen, M.M. van; Diepen, J.T.M. van; Wikselaar, P.G. van; Bikker, P. ; Jongbloed, A.W. - \ 2013
    Lelystad : Wageningen UR Livestock Research (Report / Wageningen UR Livestock Research 670) - 29
    vleeskuikens - scheenbeen - verteerbaarheid - fosfor - groeitempo - vleeskuikenresultaten - broilers - tibia - digestibility - phosphorus - growth rate - broiler performance
    The standard Ca/aP ratio (2.2) can be recommended for application in practical diets. Based on the results of this experiment, no proof was found for our hypothesis that the development of the skeleton in fast growing broilers could not keep pace with the gain of the soft tissues. This experiment showed that the P requirement was not fulfilled with the low aP level in the diet. For determination of the optimal dietary aP level, however, a dose – response experiment should be performed.
    Optimisation of selective breeding program for Nile tilapia (Oreochromis niloticus)
    Trong, T.Q. - \ 2013
    Wageningen University. Promotor(en): Johan van Arendonk, co-promotor(en): Hans Komen. - S.l. : s.n. - ISBN 9789461735447 - 176
    oreochromis niloticus - selectief fokken - veredelingsprogramma's - genetische parameters - voortplantingskenmerken - kuitschieten - voortplantingspotentieel - vruchtbaarheid - heritability - genotype-milieu interactie - groeitempo - dierveredeling - visteelt - aquacultuur - oreochromis niloticus - selective breeding - breeding programmes - genetic parameters - reproductive traits - spawning - fecundity - fertility - heritability - genotype environment interaction - growth rate - animal breeding - fish culture - aquaculture

    The aim of this thesis was to optimise the selective breeding program for Nile tilapia in the Mekong Delta region of Vietnam. Two breeding schemes, the “classic” BLUP scheme following the GIFT method (with pair mating) and a rotational mating scheme with own performance selection and natural group spawning, were investigated. In the latter scheme, the aim was to mimic natural spawning conditions of Nile tilapia to reduce the time for family production; however reconstruction of pedigrees using DNA markers to monitor inbreeding is required. Parental assignment using microsatellites and SNPs showed that exclusion- and likelihood-based methods are equally good for parental assignment, provided that good marker sets with high exclusion power, such as SNPs, are available and that all parents are sampled. Prolonged family production is problematic in BLUP breeding value estimation and could be a consequence of selection for harvest weight in Nile tilapia. Using a natural mating design with single males mated to multiple females in groups, 85% of the successful spawns were collected within 20 days. Genetic correlations between harvest weight and spawning success ranged from 0.48 to 0.52, provided that the mating period is limited to 20-32 days. We conclude that Nile tilapia favour mating in groups, and that selection for harvest weight in GIFT should improve spawning success of Nile tilapia. Moreover, harvest weight and body weight at spawning have favourable genetic correlations with number of eggs, relative fecundity, and number of swim-up fry, which are the desired characteristics for Nile tilapia seed production. High-input cages and low-input ponds are the dominant production systems for tilapia in the Mekong Delta. We show that selection in nucleus ponds will produce desired correlated responses in Nile tilapia grown in river-cages. Moreover, they are expected to develop a more rotund and thicker body shape at the same length compared to fish grown in ponds. In conclusion, we recommend the use of the ‘single male, multiple females’ mating as this will reduce the generation interval by 2 months, thereby increasing genetic gain by about 20%. A rotational mating scheme, with at least 4 cohorts, can be incorporated into the GIFT selection scheme to further reduce inbreeding, to estimate pond effects and to secure the breeding material. Finally, a reliable multiplier system is important to sustain the current Nile tilapia breeding program, which can provide sufficient improved fry (>50 million per year) for the whole Mekong Delta Nile tilapia production.

    Associations between osteochondrosis and conformation and locomotive characteristics in pigs
    Koning, D.B. de; Grevenhof, E.M. van; Laurenssen, B.F.A. ; Ducro, B.J. ; Heuven, H.C.M. ; Groot, P.N. de; Hazeleger, W. ; Kemp, B. - \ 2012
    Journal of Animal Science 90 (2012)3. - ISSN 0021-8812 - p. 4752 - 4763.
    swine breeding herds - linear type traits - leg weakness - genetic-parameters - exterior traits - danish-landrace - housing systems - finishing pigs - growth rate - sows
    Conformation and locomotive characteristics (CLC), i.e., leg conformation and gait movement patterns, may be associated with osteochondrosis (OC) in pigs. Osteochondrosis and CLC increase the risk of premature culling. This study investigated whether CLC have an explanatory value, over the previously modelled effects of sex, feeding, and housing conditions, on the occurrence and severity of OC in several joints and at the animal level. At 154 to 156 d of age, 267 pigs were subjectively scored on 9 conformation and 2 locomotive characteristics. Scoring was performed on a 9-point linear grading scale. For conformation characteristics, score 5 indicated normal conformation and scores 1 and 9 indicated severe deviations from normal. For the locomotive characteristics, score 1 indicated normal locomotion and score 9 indicated severe deviation from normal. At 161 to 176 d of age, pigs were slaughtered and joints were dissected for macroscopic evaluation of OC status. Results showed that swaying hindquarters and a stiffer gait were associated with higher scores for OC in, respectively, the femoropatellar (P = 0.018) and tarsocrural joint (P = 0.005); smaller inner claws as compared to the outer claws of the front legs was associated with lower scores for OC than equally sized claws in the femoropatellar joint (P = 0.021) and on animal level (P = 0.010); steep and weak pasterns of the front legs were associated with higher scores for OC in the elbow joint (P = 0.004) and on animal level (P = 0.018); X-shaped hind legs was associated with higher scores for OC on animal level (P = 0.037); and steep and weak pasterns of the hind legs were associated with lower scores for OC than normal conformation in the tarsocrural joint (P = 0.05). This study found several CLC that were associated with OC in several joints and at an animal level. This study showed that certain CLC might be used as indicators of OC and included in the criteria for selection of replacement animals for the breeding herd.
    Effect of variations in concentration of algae and silt on filtration and growth of the razor clam (Ensis directus, Conrad)
    Kamermans, P. ; Dedert, M. - \ 2012
    Yerseke : IMARES (Report / IMARES Wageningen UR C017/11) - 69
    ensis - voedselopname - algen - silt - groeitempo - filtratie - kustwateren - noordzee - food intake - algae - growth rate - filtration - coastal water - north sea
    As part of a collaboration between the research programme Knowledge for Primary Processes Silt of Rijkswaterstaat Waterdienst NWOB (department of Infrastructure and Environment, MinIenM, RWS) and the Monitoring programme Sand extraction RWS and the LaMER Foundation, RWS-WD NWOB requested further research into the relation between food availability and Ensis production. The aim is to better understand the effect of different algae and silt concentrations on filtration and growth rates and improve prediction of effects. Laboratory experiments were carried out with Ensis directus to estimate food intake rate and growth rate as a function of food density and clam size. Growth experiments carried out in 2010 showed that the species seems to be very fragile as shown by the low growth rates and high mortality rates. Improvements designed to optimize the experimental conditions, survival rates and experimental set-up were implemented in 2011. These were: experimental animals were collected with a box corer instead of a suction dredge; animals were kept in cylinders without sediment, but their shells were closed with elastic bands during the filtration experiments; circular tanks were used with increased water movement; the diet during the growth experiment consisted of two species of algae. Two food levels were tested: low food availability (6.5 μg Chla/l) and high food availability (16.5 μg Chla/l) at four silt concentrations (0, 50, 150 and 300 mg/l). Only the highest silt concentration induced a reduction in filtration rate. Food level did not influence filtration rate of Ensis, but intake rate is higher at the high food concentration, because more algal cells are present in a certain volume of water. Longterm (10 weeks) exposure to silt concentrations of 300 mg/l showed significantly higher growth than the 150 mg/l treatment indicating that exposure to a high silt concentration did not induce a reduction in growth. Long-term (10 weeks) exposure to a food level of 6.5 ug chla per liter reduced shell growth of Ensis compared to growth at 16.5 ug chla per liter. The filtration and growth rate results are used in a modelling study on growth and condition of Ensis during sand extraction 2013-2017 (Schellekens, in prep). The conclusions of this study give more notion of the effects of sand extraction in the coastal zone of the North Sea on the viability of the razor clam Ensis directus. Sand extraction always goes together with an increase of silt concentration in the water column. This reduces the light conditions for algal growth which reduces the food availability for Ensis. The laboratory experiments suggest that Ensis is more sensitive to a reduction in algal concentration than to an increase in silt concentration. Some discussion is given on the implications of the results for the management of sand extraction.
    First pioneering laboratory experiments on filtration, respiration and growth of the razor clam (Ensis directus, Conrad)
    Kamermans, P. ; Brummelhuis, E.B.M. ; Wijsman, J.W.M. - \ 2011
    Yerseke : IMARES (Report / IMARES Wageningen UR C115/11) - 48
    ensis - voedsel - ademhaling - filtratie - groeitempo - mariene ecologie - noordzee - food - respiration - filtration - growth rate - marine ecology - north sea
    In Dutch marine circumstances, sand extraction releases silt into the water column. The extra silt can reduce light penetration into the water and consequently algal growth. To predict potential effects of an expansion of sand extraction activities it is necessary to know possible impacts on the environment. Ensis directus, a dominant species web of the North Sea coastal zone, has a key position in the food web. Therefore, it was selected as model species in this study to predict the effects of the reduced food conditions due to sand extraction on the growth of E. directus. A DEB (Dynamic Energy Budget) model is in development. This study describes the basic experiments that have been done to determine empirical relations between clam size or food concentration and filtration, respiration and growth rates necessary for the DEB modelling. Also, the basic values on physiology itself have their value because little is known on this species. Filtration and respiration rates were measured at four food levels (2, 5, 20 and 40 μg chlorophyll a/l). Clam shell length varied from 42 to 135 mm. Filtration rate decreased with an increase in clam size from maximally 3.3 lh-1 g-1 ash-free dry weight (ADW) to 0. lh-1 g-1 ADW. There was no relation between food concentration on filtration rate. Respiration rates showed a similar decrease with clam size from maximally 5000 mg O2 lh-1 g-1 ADW to 1500 mg O2 lh-1 g-1 ADW. In addition, an increase in respiration rate was found with an increase in food concentration. In the growth experiment five food levels were tested (0, 2, 5, 20 and 40 μg chlorophyll a/l).Clams smaller than 75 mm shell length showed more growth (up to 1% increase in wet weight (WW) per day or 0.3% shell length per day) than larger clams (maximally 0.16% increase in WW per day or 0.01% shell length per day). Growth rates showed an increase with increased food concentration.
    Dynamic Energy Budget (DEB) parameters for ensis directus
    Wijsman, J.W.M. - \ 2011
    Yerseke : IMARES (Report / IMARES Wageningen UR C116/11) - 39
    ensis - energie - voedselopname - groeitempo - milieu - mariene ecologie - energy - food intake - growth rate - environment - marine ecology
    In this report a Dynamic Energy Budget (DEB) model for razor clams (Ensis directus) is presented. A DEB model is a generic model describing growth and development of individual organisms as a function of environmental conditions. The DEB model for Ensis directus is based on the standard DEB model. The species specific primary DEB parameters are estimated with the Add_my_pet procedure, using literature data and the results of laboratory experiments with Ensis directus. The performance of the model is demonstrated by theoretical model experiments with varying environmental conditions. In following projects, the model will be used to predict and quantify the effects of sand mining on the shellfish community in the Dutch coastal zone. For this purpose the functional response of the model should be adapted so that the combined effect of changing phytoplankton and suspended sediment concentration on the uptake rate can be simulated.
    Brief of requirements of the broiler = Programma van eisen van het vleeskuiken
    Hoeks, C. ; Bokkers, E.A.M. ; Bos, A.P. ; Jong, I.C. de; Janssen, A.P.H.M. ; Groot Koerkamp, P.W.G. - \ 2011
    Lelystad : Wageningen UR Livestock Research (Report / Wageningen UR Livestock Research 517) - 46
    pluimveehouderij - kuikenproductie - vleesproductie - groeitempo - dierenwelzijn - poultry farming - chick production - meat production - growth rate - animal welfare
    This report lists the brief of requirements of the broiler, based on her needs (also listed). The BoR indicates the actor’s needs with regards to the animal husbandry system. BoR of the main actors are incorporated in the redesign of a broiler husbandry system in the project Tasteful Broilers.
    Extra stuurmogelijkheden met leds en spaarlampen: Anjerteelt kan zonder gloeilamp (interview met o.a. Frank van der Helm)
    Kamminga, H. ; Helm, F.P.M. van der - \ 2011
    Vakblad voor de Bloemisterij 66 (2011)25. - ISSN 0042-2223 - p. 30 - 31.
    anjers - belichting - kunstlicht - groeitempo - groeikromme - kwekers - agrarische bedrijfsplanning - carnations - illumination - artificial light - growth rate - growth curve - growers - farm planning
    De wegval van gloeilampen is voor anjerstelers lastig, maar niet onoverkomelijk. Onderzoek van WUR Glastuinbouw wijst erop dat led- en spaarlampen goede vervangers zijn. Welke het beste voldoet hangt af van het doel van de tuinder: kwaliteit, snelheid of productie.
    Extrapolating toxic effects on individuals to the population level: the role of dynamic energy budgets
    Jager, T. ; Klok, T.C. - \ 2010
    Philosophical Transactions of the Royal Society B. Biological sciences 365 (2010)12. - ISSN 0962-8436 - p. 3531 - 3540.
    earthworm dendrobaena-octaedra - multiple end-points - lumbricus-rubellus - intrinsic rate - growth rate - life-cycle - models - reproduction - copper - tests
    The interest of environmental management is in the long-term health of populations and ecosystems. However, toxicity is usually assessed in short-term experiments with individuals. Modelling based on dynamic energy budget (DEB) theory aids the extraction of mechanistic information from the data, which in turn supports educated extrapolation to the population level. To illustrate the use of DEB models in this extrapolation, we analyse a dataset for life cycle toxicity of copper in the earthworm Dendrobaena octaedra. We compare four approaches for the analysis of the toxicity data: no model, a simple DEB model without reserves and maturation (the Kooijman–Metz formulation), a more complex one with static reserves and simplified maturation (as used in the DEBtox software) and a full-scale DEB model (DEB3) with explicit calculation of reserves and maturation. For the population prediction, we compare two simple demographic approaches (discrete time matrix model and continuous time Euler–Lotka equation). In our case, the difference between DEB approaches and population models turned out to be small. However, differences between DEB models increased when extrapolating to more field-relevant conditions. The DEB3 model allows for a completely consistent assessment of toxic effects and therefore greater confidence in extrapolating, but poses greater demands on the available data.
    Growth and metabolism of sponges
    Koopmans, M. - \ 2009
    Wageningen University. Promotor(en): Rene Wijffels, co-promotor(en): Dirk Martens. - [S.l. : S.n. - ISBN 9789085854418 - 192
    sponsen - seizoengroei - biologische productie - metabolisme - groeitempo - in vitro kweek - geneesmiddelen - bioactieve verbindingen - sponges - seasonal growth - biological production - metabolism - growth rate - in vitro culture - drugs - bioactive compounds
    Sponges (phylum Porifera) are multi cellular filter-feeding invertebrate animals living attached to a substratum in mostly marine but also in freshwater habitats. The interest in sponges has increased rapidly since the discovery of potential new pharmaceutical compounds produced by many sponges. An enormous amount of different chemical structures have been found. Thus far no sustainable production technique has been developed for these marine natural products, because not sufficient knowledge is present about the needs of sponges for both growth and bioactive compound production. The aim of this thesis was to get a better understanding of the growth and metabolism of sponges and of their nutritional needs. Aquaculture is thus far the best method to produce these compounds, although also this technique is not fully developed.
    To gain more insight in the nutritional needs for growth, we studied the growth rate of Haliclona oculata in its natural environment, Oosterschelde, the Netherlands, and monitored environmental parameters in parallel (Chapter 2). A stereo photogrammetry approach was used for measuring growth rates. Stereo pictures were taken and used to measure volumetric changes monthly during 1 year. The volumetric growth rate of Haliclona oculata showed a seasonal trend with the highest average specific growth rate measured in May: 0.012±0.004 day−1. In our study a strong positive correlation (p<0.01) was found for growth rate with temperature, algal biomass (measured as chlorophyll a), and carbon and nitrogen content in suspended particulate matter. Thus growth rate seems to be dependent on these factors. No correlation was found with dissolved organic carbon, suggesting that Haliclona oculata is more dependent on particulate organic carbon. To obtain more knowledge about the carbon requirements for growth by sponges, respiration rate and clearance rate were measured in situ in Haliclona oculata and compared to the earlier measured growth rate (Chapter 3). The net growth efficiency, being the ratio of carbon incorporated in biomass and the total carbon used by the sponge for respiration and growth, was found to be 0.10 ± 0.013. Thus, about 10% of the total used carbon was fixed in biomass and over 90% was used for generating energy for growth, maintenance, reproduction and pumping. H. oculata had 2.5 μmol C available for every μmol O2 consumed. A value of 0.75 for the respiratory quotient (RQ in μmol CO2 μmol O2 -1) is the average value reported in literature for different marine invertebrates. Thus, carbon was available in excess to meet the respiratory demand. We found that only 34% of the particulate carbon pumped through the sponge was used for both respiration and growth. Oxygen was not the limiting factor for growth, since only 3.3% of the oxygen pumped through the sponge body was used. Our results indicate that both oxygen and carbon availability are not limiting. The low growth efficiency agrees with the low growth rates found for many sponges.
    In order to produce drugs by culturing sponges their growth must be improved. To improve growth, basic knowledge about how food sources are used by the sponge is needed. To find the exact relation between food retained and food converted to sponge biomass we need to be able to distinguish between feed components and sponge biomass, which means we need biomarkers for the feed and for the sponge. The fatty acid (FA) composition of organisms is specific and can therefore be used as biomarkers. We identified and compared fatty acid profiles of five different sponges in three habitats with those in the suspended particulate matter (SPM) in the surrounding water (Chapter 4). Haliclona oculata and Haliclona xena from the Oosterschelde, Haliclona xena and Halichondria panicea from Lake Veere, both in The Netherlands and Dysidea avara and Aplysina aerophoba from the Mediterranean were studied. In the SPM we found comparable FAs to the FAs of sponges up to chain lengths of 28 C-atoms. Different species of sponges showed similarities, but also very different FA profiles, while they were collected from the same habitat at the same moment. The biomarkers for diatoms and dinoflagellates were abundantly found in all sponges except A. aerophoba as this sponge relies mostly on bacterial food sources based on the many bacterial FAs found in this sponge. In all species, except A. aerophoba, C26:3(5,9,19) and C26:2(5,9) were very abundantly present. These FAs were also abundant in the SPM, while it was stated in literature that these compounds are very typical for sponges. Several FA biomarkers were found for the different sponges.
    Fatty acid composition is dependent on different factors like food availability and temperature and thus the composition will change in the different seasons. We have studied fatty acid composition and stable isotope 13C natural abundance of suspended particulate matter (SPM) from seawater and sponges in different seasons in the same locations as in chapter 4 (Chapter 5). 13C natural abundance can be used to find the origin of compounds, as the 13C values of compounds are similar to the values from their original producers. The FA concentration variation in sponges was related to changes in fatty acid concentration in SPM. 13C natural abundance in sponge specific FAs showed very limited seasonal variation at all sites. Algal FAs in sponges were mainly acquired from the SPM through active filtration in all seasons. Sponge specific FAs had similar 13C ratios as algal FAs in May at the two Dutch sites, suggesting that sponges were mainly growing during spring and probably summer. During autumn and winter, they were still actively filtering, but the food collected during this period had little effect on sponge 13C values suggesting limited growth. The bacterial sponge A. aerophoba relies mostly on the symbiotic bacteria. In all sponges we found that the ω7 longer chain FAs, C24:1(17) and C26:3(5,9,19) could be traced back to be of bacterial origin. Using a 13C pulse-chase approach metabolic rate can be studied inside organisms. The carbon metabolism of two marine sponges, Haliclona oculata from the Oosterschelde (The Netherlands) and Dysidea avara from the Mediterranean (Spain), has been studied (Chapter 6). The sponges were fed 13C labelled diatom (Skeletonema costatum) for 8 hours in a closed system during which they took up between 75 and 85 % of the diatoms added. At different times whole sponges were sampled for total 13C enrichment, fatty acid composition and 13C enrichment in these fatty acids. During the first day the level of 13C label inside the sponges stayed the same after which the 13C label was metabolized and excreted. Algal biomarkers present in the sponges were highly labeled after feeding and their labeling levels decreased from the second day until no label was left 10 days after enrichment. The sponge specific long chain C26 fatty acids incorporated 13C label already during the first day and the amount of 13C label inside these FAs kept increasing until 3 weeks after labeling. Thus, the algae fed to the sponges were taken up by the sponges within 8 hrs and first conversion started during the first day. Conversion of label occurred at least until at least 3 weeks after feeding.
    In different studies it was shown that sponges grow slow, but are able to regenerate damaged tissue fast. Moreover, it has been found that damaged tissue coincides with higher secondary metabolite production. Therefore, we were interested in carbon metabolic rate changes after damaging sponge tissue. We have examined the change of carbon metabolic rate of fatty acid synthesis due to mechanical damage of sponge tissue in Haliclona oculata and Dysidea avara (Chapter 7). Metabolic studies were performed by feeding sponges with 13C labeled biomass of diatom, Pheaodactylum tricornutum, either after or before damaging and tracing back the 13C content in the damaged and healthy tissue. Filtration and respiration rate in both sponges responded quickly to damage. For the finger-sponge H. oculata the rate of respiration was reduced immediately after damage. 6 Hours after damage the filtration rate increased to a level that was higher than the starting value, while the respiration rate returned to the initial value before damage. For the encrusting sponge D. avara the filtration rate also decreased directly after damage, but in this case it did not return to the value before damage after one day. Respiration was not measured for D. avara. The 13C data revealed that H. oculata has a higher metabolic rate in the tips where growth occurs compared to the rest of the tissue and that the metabolic rate is increased after damage of the tissue. For D. avara no differences were found between damaged and non damaged tissue. Thus far it is still not fully understood why, when, where and how bioactive metabolites are produced in sponges. For the near future sea-based sponge culture seems to be the best production method. However, for controlled production in a defined system it is better to develop in vitro production methods. This could be in vitro sponge culture or sponge cell culture, culture methods for symbionts or transfer production routes into another host. We still have insufficient information about the background of metabolite production in sponges. Before culture methods are developed we should focus on factors that induce metabolite production, which could be done in the natural habitat by studying the relation between stress factors (such as predation) and the production of bioactive metabolites. Next, the biosynthetic pathway of metabolite production should be unraveled, as well as the genes involved. The location of production within the sponge should be identified in order to choose between sponge cell culture and symbiont culture. Alternatively the biosynthetic pathways could be introduced into hosts that can be easily cultured in bioreactors. Chapter 8 discusses the current state of sponge metabolite production and the steps that need to be taken to develop commercial production techniques. The different possible production techniques are also discussed.
    Comparing feed intake, utilization of protein and energy for growth and body composition in S. solea fed natural and commercial diets
    Ende, S.S.W. ; Kroeckel, S. ; Schrama, J.W. ; Schneider, O. ; Verreth, J.A.J. - \ 2009
    Yerseke : IMARES (Report / Wageningen IMARES nr. C045/09) - 23
    vissen - tong (vis) - voeropname - groeitempo - voedingsfysiologie - polychaeta - voederconversievermogen - fishes - dover soles - feed intake - growth rate - nutrition physiology - polychaeta - feed conversion efficiency
    The present work was carried out to study the effect of polychaete Nereis virens on feed intake, utilization of protein and energy for growth and body composition in sole (S. solea). It is hypothesized that intake, efficiencies of protein utilization and growth rates obtained for sole fed ragworm are comparable to those previously reported for S. solea. The mussel M. edulis was used as a reference diet to allow comparisons of present results with those obtained previously, which until today serve as reference for optimum growth in sole. Intake, efficiencies of utilization for protein and energy for growth and growth rates obtained for sole fed ragworm are expected to be higher compared to commercial feed. A commercial feed, commonly used for turbot but also in sole culture served as a second reference diet to discuss differences between natural and commercial feeds.
    Diagnosing declining grassland wader populations using simple matrix models
    Klok, C. ; Roodbergen, M. ; Hemerik, L. - \ 2009
    Animal Biology 59 (2009)1. - ISSN 1570-7555 - p. 127 - 144.
    redshank tringa-totanus - godwits limosa-limosa - survival rates - conservation biology - breeding success - growth rate - management - netherlands - farmland - schemes
    Many populations of wader species have shown a strong decline in number in Western-Europe in recent years. The use of simple population models such as matrix models can contribute to conserve these populations by identifying the most profitable management measures. Parameterization of such models is often hampered by the availability of demographic data (survival and reproduction). In particular, data on survival in the pre-adult (immature) stage of wader species that remain in wintering areas outside Europe are notoriously difficult to obtain, and are therefore virtually absent in the literature. To diagnose population decline in the wader species; Black-tailed Godwit, Curlew, Lapwing, Oystercatcher, and Redshank, we extended an existing modelling framework in which incomplete demographic data can be analysed, developed for species with a pre-adult stage of one year. The framework is based on a Leslie matrix model with three parameters: yearly reproduction (number of fledglings per pair), yearly pre-adult (immature) and yearly adult (mature) survival. The yearly population growth rate of these populations and the relative sensitivity of this rate to changes in survival and reproduction parameters (the elasticity) were calculated numerically and, if possible, analytically. The results showed a decrease in dependence on reproduction and an increase in pre-adult survival of the population growth rate with an increase in the duration of the pre-adult stage. In general, adult survival had the highest elasticity, but elasticity of pre-adult survival increased with time to first reproduction, a result not reported earlier. Model results showed that adult survival and reproduction estimates reported for populations of Redshank and Curlew were too low to maintain viable populations. Based on the elasticity patterns and the scope for increase in actual demographic parameters we inferred that conservation of the Redshank and both Curlew populations should focus on reproduction. For one Oystercatcher and the Black-tailed Godwit populations we suggested a focus on both reproduction and pre-adult survival. For the second Oystercatcher population pre-adult survival seemed the most promising target for conservation. And for the Lapwing populations all demographic parameters should be considered.
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