Staff Publications

Staff Publications

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

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

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

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

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Glycine plus serine requirement of broilers fed low-protein diets : a dose response study
Harn, J. van; Dijkslag, M.A. ; Krimpen, M.M. van - \ 2018
Wageningen : Wageningen Livestock Research (Wageningen Livestock Research report 1116) - 36
In a study with 910 Ross 308 male broilers, housed in 70 floor pens bedded with wood shavings, the effect of digestible glycine+serine content (5 levels ranging from 12.4 to 15.7 g/kg and 11.4 to 14.9 g/kg in grower and finisher diets, respectively) in low-protein diets was studied from 10 – 35 days of age. In this study, also the glycine-sparing effect of threonine was studied. In total seven different treatments were studied: a control treatment (a normal/high protein diet), five low-protein dietary treatments with increasing levels of digestible glycine+serine and a low-protein dietary treatment in which extra threonine was supplemented to the diet with the lowest glycine+serine level. Growth performance results, slaughter yields, litter quality, litter composition and footpad score were measured. This study showed that the glycine+serine level in low-protein feed did not have a noticeable effect on the production results, slaughter yields, litter quality and foot pad lesion. Based on this study it was concluded that a digestible glycine+serine dose in low-protein diets of 12.4 g/kg and 11.4 g/kg in grower and finisher phase, respectively, is sufficient.
Genetic covariance components within and among linear type traits differ among contrasting beef cattle breeds
Doyle, Jennifer L. ; Berry, Donagh P. ; Walsh, Siobhan W. ; Veerkamp, Roel F. ; Evans, Ross D. ; Carthy, Tara R. - \ 2018
Journal of Animal Science 96 (2018)5. - ISSN 0021-8812 - p. 1628 - 1639.
Beef - Breeds - Cattle - Type traits

Linear type traits describing the skeletal, muscular, and functional characteristics of an animal are routinely scored on live animals in both the dairy and beef cattle industries. Previous studies have demonstrated that genetic parameters for certain performance traits may differ between breeds; no study, however, has attempted to determine if differences exist in genetic parameters of linear type traits among breeds or sexes. Therefore, the objective of the present study was to determine if genetic covariance components for linear type traits differed among five contrasting cattle breeds, and to also investigate if these components differed by sex. A total of 18 linear type traits scored on 3,356 Angus (AA), 31,049 Charolais (CH), 3,004 Hereford (HE), 35,159 Limousin (LM), and 8,632 Simmental (SI) were used in the analysis. Data were analyzed using animal linear mixed models which included the fixed effects of sex of the animal (except in the investigation into the presence of sexual dimorphism), age at scoring, parity of the dam, and contemporary group of herd-date of scoring. Differences (P < 0.05) in heritability estimates, between at least two breeds, existed for 13 out of 18 linear type traits. Differences (P < 0.05) also existed between the pairwise within-breed genetic correlations among the linear type traits. Overall, the linear type traits in the continental breeds (i.e., CH, LM, SI) tended to have similar heritability estimates to each other as well as similar genetic correlations among the same pairwise traits, as did the traits in the British breeds (i.e., AA, HE). The correlation between a linear function of breeding values computed conditional on covariance parameters estimated from the CH breed with a linear function of breeding values computed conditional on covariance parameters estimated from the other breeds was estimated. Replacing the genetic covariance components estimated in the CH breed with those of the LM had least effect but the impact was considerable when the genetic covariance components of the AA were used. Genetic correlations between the same linear type traits in the two sexes were all close to unity (≥0.90) suggesting little advantage in considering these as separate traits for males and females. Results for the present study indicate the potential increase in accuracy of estimated breeding value prediction from considering, at least, the British breed traits separate to continental breed traits.

Effects of dietary protein level and age at photo stimulation on reproduction traits of broiler breeders and progeny performance
Emous, R.A. van; Cruz, C.E. de la; Naranjo, V.D. - \ 2018
Poultry Science 97 (2018)6. - ISSN 0032-5791 - p. 1968 - 1979.
age at photo stimulation - broiler breeder - dietary crude protein - progeny - reproduction

A study with a 2 × 2 factorial arrangement was conducted to determine the effects of 2 dietary crude protein levels, high (CPh) or low (CPl), supplemented with free amino acids (AA), and 2 ages at photo stimulation (PS) - early (21 wk; PSe) or late (23 wk; PSl) - on reproduction traits of broiler breeders and progeny performance. Diets were isocaloric, and calculated CP content of the CPl diets was 15 g/kg lower than the CPh diets during all phases. A total of 480 female and 64 male Ross 308 breeders of 20 wk of age were used. Total egg production was similar between CPl and CPh birds during phase 1 and 2 but was reduced by 2.8 eggs for CPl birds during phase 3. For the overall laying period, CPl birds tended (P = 0.075) to produce 4.7 fewer total eggs. Hatchability of set eggs was similar between CPl and CPh birds during phases 1 and 2 but tended (P = 0.064) to be lower for CPl birds in phase 3. PSe birds showed an advanced age at sexual maturity and age at peak production of 4.6 and 5.3 d, respectively, resulting in 2.5 more total eggs during phase 1. During phase 1, PSe birds showed an almost 5% increased fertility. Chick production in phase 1 was higher for PSe birds resulting in a tendency (P = 0.071) to higher overall chick production of almost 8 chicks. Progeny from early PS breeders showed an overall significant lower feed conversion ratio (FCR). It was concluded that egg and chick production during phases 1 and 2 were not affected by dietary CP level, but egg and chick production was reduced for CPl birds during phase 3. On the other hand, PSe birds showed an increased number of chicks. It is possible to decrease CP level of breeder diets with comparable reproduction from 22 to 46 wk; however, this is questionable for phase 3. For maximal chick production, early PS is recommended.

Consumer-friendly food allergen detection : moving towards smartphone-based immunoassays
Ross, Georgina M.S. ; Bremer, Monique G.E.G. ; Nielen, Michel W.F. - \ 2018
Analytical and Bioanalytical Chemistry (2018). - ISSN 1618-2642 - p. 1 - 19.
Citizen science - Consumer - Food allergen - Immunoassay - Multiplex - Smartphone
In this critical review, we provide a comprehensive overview of immunochemical food allergen assays and detectors in the context of their user-friendliness, through their connection to smartphones. Smartphone-based analysis is centered around citizen science, putting analysis into the hands of the consumer. Food allergies represent a significant worldwide health concern and consumers should be able to analyze their foods, whenever and wherever they are, for allergen presence. Owing to the need for a scientific background, traditional laboratory-based detection methods are generally unsuitable for the consumer. Therefore, it is important to develop simple, safe, and rapid assays that can be linked with smartphones as detectors to improve user accessibility. Smartphones make excellent detection systems because of their cameras, embedded flash functions, portability, connectivity, and affordability. Therefore, this review has summarized traditional laboratory-based methods for food allergen detection such as enzyme-linked-immunosorbent assay, flow cytometry, and surface plasmon resonance, and the potential to modernize these methods by interfacing them with a smartphone readout system, based on the aforementioned smartphone characteristics. This is the first review focusing on smartphone-based food-allergen detection methods designed with the intention of being consumer-friendly. [Figure not available: see fulltext.]
High spatial variation in population size and symbiotic performance of Rhizobium leguminosarum bv. trifolii with white clover in New Zealand pasture soils
Wakelin, Steven ; Tillard, Guyléne ; Ham, Robert van; Ballard, Ross ; Farquharson, Elizabeth ; Gerard, Emily ; Geurts, Rene ; Brown, Matthew ; Ridgway, Hayley ; O’Callaghan, Maureen - \ 2018
PLoS One 13 (2018)2. - ISSN 1932-6203
Biological nitrogen fixation through the legume-rhizobia symbiosis is important for sustainable pastoral production. In New Zealand, the most widespread and valuable symbiosis occurs between white clover (Trifolium repens L.) and Rhizobium leguminosarum bv. trifolii (Rlt). As variation in the population size (determined by most probable number assays; MPN) and effectiveness of N-fixation (symbiotic potential; SP) of Rlt in soils may affect white clover performance, the extent in variation in these properties was examined at three different spatial scales: (1) From 26 sites across New Zealand, (2) at farm-wide scale, and (3) within single fields. Overall, Rlt populations ranged from 95 to >1 x 108 per g soil, with variation similar at the three spatial scales assessed. For almost all samples, there was no relationship between rhizobia population size and ability of the population to fix N during legume symbiosis (SP). When compared with the commercial inoculant strain, the SP of soils ranged between 14 to 143% efficacy. The N-fixing ability of rhizobia populations varied more between samples collected from within a single hill country field (0.8 ha) than between 26 samples collected from diverse locations across New Zealand. Correlations between SP and calcium and aluminium content were found in all sites, except within a dairy farm field. Given the general lack of association between SP and MPN, and high spatial variability of SP at single field scale, provision of advice for treating legume seed with rhizobia based on field-average MPN counts needs to be carefully considered.
Butyrate presence in distinct gastrointestinal tract segments modifies differentially digestive processes and amino acid bioavailability in young broiler chickens
Moquet, P.C.A. ; Salami, S.A. ; Onrust, L. ; Hendriks, W.H. ; Kwakkel, R.P. - \ 2018
Poultry Science 97 (2018)1. - ISSN 0032-5791 - p. 167 - 176.
Butyrate - broiler - digestibility - digesta retention time - location effect
The hypothesis was tested that butyrate presence in the digesta of distinct gastrointestinal tract (GIT) segments of broilers leads to differential effects on digesta retention time, gut morphology, and proteolytic enzymatic activities, ultimately resulting in differences in protein digestibility. A total of 320 male day-old Ross 308 broilers were randomly assigned to 5 dietary treatments: 1) control (no butyrate), 2) unprotected butyrate (main activity in the crop and gastric regions), 3) tributyrin (main activity in the small intestine), 4) fat-coated butyrate (activity in the whole GIT) and 5) unprotected butyrate combined with tributyrin, each replicated 8 times. Rapeseed meal was used in combination with a fine dietary particle size in order to challenge the digestive capacity of young broilers. Birds were dissected at 22, 23, and 24 d of age and samples of digesta at various GIT locations as well as tissues were collected. Butyrate concentration varied significantly across GIT segments depending on treatment, indicating that the dietary contrasts were successful. The apparent ileal digestibility of methionine tended to increase when butyrate and/or propionate was present in colonic and cecal contents, possibly due to modifications of GIT development and digesta transit time. Butyrate presence in the digesta of the crop, proventriculus and gizzard, on the contrary, decreased the apparent ileal digestibility of several amino acids (AA). In addition, butyrate presence beyond the gizzard elicited anorexic effect that might be attributable to changes in intestinal enteroendocrine L-cells secretory activities. The present study demonstrates that, in broilers, effects of butyrate on digestive processes are conditioned by the GIT segment wherein the molecule is present and indicates its influence on digestive function and bioavailability of AA.
Effect of whole wheat inclusion and pellet diameter on pellet quality and performance in broilers
Raaijmakers, M.M.P. ; Loon, Jorik van; Elling-Staats, M.L. ; Poel, A.F.B. van der; Kwakkel, R.P. - \ 2017
- 4 p.
Whole wheat (WW) is mainly fed to broilers along with a pelleted feed, which allows birds to select particles leading to inconsistent results. WW inclusion in a pellet may require larger pellets to maintain coarse structure and pellet quality. The effect of WW vs ground wheat (GW) inclusion and pellet diameter (4 vs 6 mm) on pellet quality and performance was investigated, using a 2x2 factorial design with 6 replicates per treatment (9 Ross 308 males per pen). An additional group was fed a reference diet (RD) containing GW in a 3 mm pellet diameter. From day 0-7, all birds received a crumble starter diet (250 g/kg GW). From day 8-14, one group received the RD and the other 4 groups a 4 mm pelleted diet, which included either GW or WW. From day 15-34, half of these 4 groups received the 6 mm pelleted diets (GW or WW). Formulations of all diets from day 8-34 were similar (350 g/kg wheat). Pellet durability, tested using a Ligno tester, was the highest in the RD (75.5%), tested with sieve size 2.1 mm. When tested with sieve size 3.6 mm, GW 6 mm had the highest durability (59.7%) and the lowest durabilities were found using both sieves in WW 6 mm diets (60.8% and 36.6% for 2.1 and 3.6 mm, respectively). Feed intake (FI) and feed conversion ratio (FCR) was higher for GW vs WW diets from day 8-14 (53.6 vs 51.1 g/d, P=0.032 and 1.314 vs 1.269, P=0.038, respectively). For RD the lowest FCR (1.240, P=0.031) and highest bodyweight gain (BWG) (44.0g, P=0.010) was found. From day 15-34, FI and BWG was also higher for GW vs WW diets (154.9 vs 148.6 g, P<0.001 and 107.8 vs 103.9 g, P<0.001, respectively). Furthermore, FCR was better for the 4 mm pellet compared to the 6 mm pellet (1.408 vs 1.425, P=0.014); RD showed the lowest FI (145.5 g/d, P<0.001) and BWG (102.7 g, P=0.011), FCR remained unaffected. Overall, these results showed that 4 and 6 mm pellets vs 3 mm improve FI and BWG and that WW in pellets (vs GW) reduces FI and BWG, but improves FCR.
Natural variation in Arabidopsis thaliana reveals shoot ionome, biomass, and gene expression changes as biomarkers for zinc deficiency tolerance
Campos, A.C.A.L. ; Kruijer, W.T. ; Alexander, Ross ; Akkers, R.C. ; Danku, J. ; Salt, D.E. ; Aarts, M.G.M. - \ 2017
Journal of Experimental Botany 68 (2017)13. - ISSN 0022-0957 - p. 3643 - 3656.
Zinc (Zn) is an essential nutrient for plants, with a crucial role as a cofactor for many enzymes. Approximately one-third of the global arable land area is Zn deficient, leading to reduced crop yield and quality. To improve crop tolerance to Zn deficiency, it is important to understand the mechanisms plants have adopted to tolerate suboptimal Zn supply. In this study, physiological and molecular aspects of traits related to Zn deficiency tolerance were examined in a panel of 19 Arabidopsis thaliana accessions. Accessions showed a larger variation for shoot biomass than for Zn concentration, indicating that they have different requirements for their minimal Zn concentration required for growth. Accessions with a higher tolerance to Zn deficiency showed an increased expression of the Zn deficiency-responsive genes ZIP4 and IRT3 in comparison with Zn deficiency-sensitive accessions. Changes in the shoot ionome, as a result of the Zn treatment of the plants, were used to build a multinomial logistic regression model able to distinguish plants regarding their Zn nutritional status. This set of biomarkers, reflecting the A. thaliana response to Zn deficiency and Zn deficiency tolerance, can be useful for future studies aiming to improve the performance and Zn status of crop plants grown under suboptimal Zn concentrations.
Effect of iso-energetic exchange of dietary fat and starch on growth performance and body composition of broilers : Experiment 2
Veldkamp, T. ; Dekker, R. ; Smit-Heinsbroek, A. ; Lee, A. van der; Jansman, A.J.M. - \ 2017
Wageningen : Wageningen UR Livestock Research (Livestock Research rapport 1062) - 33
Dietary factors such as the concentrations of protein/amino acids, fat, and starch + sugar and their ratio, may affect the post-absorptive metabolism of energy and protein and energy deposition in the body. In a 2x3 factorial block design, the effects of two dietary crude protein (high protein (HP) vs. low protein (LP) concentrations; 200/190 vs. 170/160 g/kg) in grower and finisher phase and three dietary fat/starch concentrations (high fat (HF); fat and starch 120 and 350 g/kg, respectively, medium fat (MF); fat and starch 80 and 425 g/kg and low fat (LF); fat and starch 40 and 500 g/kg, respectively) on growth performance and body composition of Ross 308 broilers were studied (8 to 38 d). From this experiment it can be concluded that dietary energy source and protein level in isoenergetic diets, balanced for first limiting essential amino acids, influence growth performance and body composition of broilers.
Effect of iso-energetic exchange of dietary fat and starch on growth performance and body composition of broilers : Experiment 1
Veldkamp, T. ; Schamp, T. ; Harn, J. van; Dekker, R. ; Sosef, M. ; Jansman, A.J.M. - \ 2017
Wageningen : Wageningen UR Livestock Research (Livestock Research rapport 1061) - 34
Dietary factors such as the concentrations of protein/amino acids, fat, and starch + sugar and their ratio, may affect the post-absorptive metabolism of energy and protein and energy deposition in the body. In a 2x2 factorial design, the effects of two dietary crude protein (high protein (HP) vs. low protein (LP) concentrations; 200/190 vs. 170/160 g/kg in grower and finisher phase) and two dietary fat/starch concentrations; (high fat (HF); fat and starch 105 and 340 g/kg, respectively) and (low fat (LF); fat and starch 65 and 420 g/kg, respectively) on growth performance and body composition of Ross 308 broilers were studied (9 to 35 d). From this experiment it can be concluded that dietary energy source and protein level in iso-energetic diets, balanced for first limiting essential amino acids, influence growth performance and body composition of broilers.
Contribution of Dairy to Nutrient Intake in the Western Diet
Hettinga, Kasper ; Valenberg, Hein van - \ 2017
In: Nutrients in Dairy and Their Implications for Health and Disease / Watson, Ronald Ross, Collier, Robert J., Preedy, Victor R., Academic Press - ISBN 9780128097625 - p. 251 - 258.
Dairy - Dietary patterns - Minerals - Nutrient density - Omega-3 fatty acids - Protein quality - Vitamins

Milk and dairy products play an important role in providing nutrients in both Western and developing countries. Most research in this area focuses on the intake of individual nutrients from food products, like dairy products. However, nutrients are not consumed, and do not function, in isolation. Looking at nutrient intake from the perspective of whole food products, or even whole dietary patterns, may be a more suitable way to quantify the contribution of dairy to the intake of nutrients. A mathematical approach, the nutrient-rich food score, is explained and discussed in this chapter. Such models could in the future even be extended beyond nutrition (e.g., including sustainability or cost parameters) to even better guide healthy eating habits for consumers.

Comparison of Eimeria Infection Dynamics between Broiler Flocks with a Conventional or On-farm Hatching System.
Velkers, Francisca ; Jong, I.C. de; Ven, Lotte van de; Reep, L. Van de; Stegeman, A. - \ 2017
In: Proceedings of the XXthe Veterinary Poultry Congress, Edinburg. - - p. 197 - 197.
Broiler Chickens, Coddidiosis, Eimeria, Enteric Disease, On-farm hatching
An increasing trend in Europe is placing 18 days incubated eggs on trays in broiler houses for on-farm hatching. Chicks are not transported and have immediate access to food and water, which promotes early intestinal tract and immune system development. It was hypothesized that these physiological effects may affect the response to intestinal infections. Moreover, on-farm hatched chicks may be exposed to environmental Eimeria oocysts earlier than hatchery chicks. Therefore we compared Eimeria infection dynamics for in hatchery (R) and on-farm hatched (F) Ross 308 broilers in two field studies on commercial broiler farms and in one study in an experimental facility.
In field study 1, a poultry house was divided in a part with F and R hatching for two rounds. Ten flocks on four farms were included in field study 2 with on each farm F flocks and R flocks originating from the same parent flock. In study 3, four groups of F and R broilers were placed in experimental pens, each with 1150 birds from the same parent flock. From the second week of life onwards, oocyst excretion in faeces (OPG = oocysts per g), collected in weekly (study 2) or biweekly (studies 1 and 3) intervals, was determined with the McMaster counting technique. In both field studies an Eimeria-species specific OPG was determined with qPCR (GD Deventer, the Netherlands) on weekly pools of colonic and caecal faeces collected three times per week. Lesion scores for E. acervulina, E. maxima and E. tenella were determined during post-mortem examinations of five to six randomly selected birds on one to three occasions per production round from the third week of life onwards. Use of coccidiostats, antibiotics and production performance was recorded.
Results of qPCR showed that E. acervulina, E. tenella (studies 1 and 2) and E. maxima (study 2) were detected, without differences in species distribution between F and R flocks. In study 3, where qPCR results were not available, lesion scores indicated presence of E. acervulina and E. maxima, but not E. tenella in both F and R flocks. In all studies lesion scores were generally mild and not significantly different between F and R flocks. Oocyst excretion patterns throughout the production period were similar for F and R flocks in study 1, but in study 2 F flocks on average showed a later excretion peak (R peaked between day 22-28 and F between days 22-28 or 28-34). In study 3 oocyst output dynamics were comparable in F and R pens. In this study oocyst excretion did not reach a clear peak by the end of the round at day 40, due to a late (day 33) start of excretion. OPG determined by qPCR and the McMaster technique in studies 1 and 2 gave similar results. Production performance could not be compared between F and R flocks in the field studies, due to differences in disease occurrence and antibiotic treatments.
Only small differences in the course of Eimeria infections were detected, but the number of flocks was too small to draw accurate conclusions about effects of hatching system on coccidiosis and how this affects production performance. Small differences in infection dynamics, e.g. time of peak excretion, may affect body weight at slaughter or influence opportunities for secondary infections. Therefore, if more commercial on-farm hatching and comparable reference flocks become available, further research is warranted.
Nitrogen performance indicators for dairy production systems
Klein, Cecile A.M. De; Monaghan, Ross M. ; Alfaro, Marta A. ; Gourley, Cameron J.P. ; Oenema, Oene ; Mark Powell, J. - \ 2017
Soil Research 55 (2017)5-6. - ISSN 1838-675X - p. 479 - 488.
animal NUE - crop NUE - dairy systems - nitrogen use efficiency (NUE) - whole-farm NUE
Nitrogen (N) is invaluable for maintaining agricultural production, but its use, and particularly inefficient use, can lead to environmental losses. This paper reviews N use efficiency (NUE) and N surplus indicators for dairy production systems to assess their utility for optimising N use outcomes and minimising environmental N losses. Using case-study examples, we also assess realistic goals for these indicators and discuss key issues associated with their use. Published whole-farm NUE and whole-farm N surplus values ranged within 10-65% and 40-700kg N ha-1 year-1 respectively. In a study of five catchments across New Zealand, whole-farm NUE was more strongly affected by catchment differences in soil and climatic conditions than by differences in management. In contrast, whole-farm N surplus differed both between-and within-catchments and was a good indicator of N losses to water. Realistic goals for both NUE and N surplus thus depend on the agro-climatic context of the dairy system and on its economic and environmental goals. Crop and animal NUE values can be valuable indicators for optimising fertiliser and feed use and minimising N losses. However, global or national whole-farm NUE values appear of limited value if the ultimate goal for setting targets is to reduce the environmental impact of N use; whole-farm level targets based on N surplus would be a more useful indicator for this purpose. Our review also reinforces the importance of standardising the variables that should be used to estimate NUE and N surplus values, to ensure equitable comparisons between different systems. Finally, NUE and N surplus targets should also be set in the context of other agro-environmental considerations.
Effects of rye inclusion in grower diets on immune competence-related parameters and performance in broilers
Krimpen, M.M. van; Torki, M. ; Schokker, D. - \ 2017
Poultry Science 96 (2017)9. - ISSN 0032-5791 - p. 3324 - 3337.
An experiment was conducted to investigate the effects of dietary inclusion of rye, a model ingredient to increase gut viscosity, between 14 and 28 d of age on immune competence-related parameters and performance of broilers. A total of 960 day-old male Ross 308 chicks were weighed and randomly allocated to 24 pens (40 birds per pen), and the birds in every 8 replicate pens were assigned to 1 of 3 experimental diets including graded levels, 0%, 5%, and 10% of rye. Tested immune competence-related parameters were composition of the intestinal microbiota, genes expression in gut tissue, and gut morphology. The inclusion of 5% or 10% rye in the diet (d 14 to 28) resulted in decreased performance and litter quality, but in increased villus height and crypt depth in the small intestine (jejunum) of the broilers. Relative bursa and spleen weights were not affected by dietary inclusion of rye. In the jejunum, no effects on number and size of goblet cells, and only trends on microbiota composition in the digesta were observed. Dietary inclusion of rye affected expression of genes involved in cell cycle processes of the jejunal enterocyte cells, thereby influencing cell growth, cell differentiation and cell survival, which in turn were consistent with the observed differences in the morphology of the gut wall. In addition, providing rye-rich diets to broilers affected the complement and coagulation pathways, which among others are parts of the innate immune system. These pathways are involved in eradicating invasive pathogens. Overall, it can be concluded that inclusion of 5% or 10% rye to the grower diet of broilers had limited effects on performance. Ileal gut morphology, microbiota composition of jejunal digesta, and gene expression profiles of jejunal tissue, however, were affected by dietary rye inclusion level, indicating that rye supplementation to broiler diets might affect immune competence of the birds.
Large-scale GWAS identifies multiple loci for hand grip strength providing biological insights into muscular fitness
Willems, Sara M. ; Wright, D.J. ; Day, Felix R. ; Trajanoska, Katerina ; Joshi, P.K. ; Morris, John A. ; Matteini, Amy M. ; Garton, Fleur C. ; Grarup, Niels ; Oskolkov, Nikolay ; Thalamuthu, Anbupalam ; Mangino, Massimo ; Liu, Jun ; Demirkan, Ayse ; Lek, Monkol ; Xu, Liwen ; Wang, Guan ; Oldmeadow, Christopher ; Gaulton, Kyle J. ; Lotta, Luca A. ; Miyamoto-Mikami, Eri ; Rivas, Manuel A. ; White, Tom ; Loh, Po Ru ; Aadahl, Mette ; Amin, Najaf ; Attia, John R. ; Austin, Krista ; Benyamin, Beben ; Brage, Søren ; Cheng, Yu Ching ; Ciȩszczyk, Paweł ; Derave, Wim ; Eriksson, Karl Fredrik ; Eynon, Nir ; Linneberg, Allan ; Lucia, Alejandro ; Massidda, Myosotis ; Mitchell, Braxton D. ; Miyachi, Motohiko ; Murakami, Haruka ; Padmanabhan, Sandosh ; Pandey, Ashutosh ; Papadimitriou, Ioannis ; Rajpal, Deepak K. ; Sale, Craig ; Schnurr, Theresia M. ; Sessa, Francesco ; Shrine, Nick ; Tobin, Martin D. ; Varley, Ian ; Wain, Louise V. ; Wray, Naomi R. ; Lindgren, Cecilia M. ; MacArthur, Daniel G. ; Waterworth, Dawn M. ; McCarthy, Mark I. ; Pedersen, Oluf ; Khaw, Kay Tee ; Kiel, Douglas P. ; Pitsiladis, Yannis ; Fuku, Noriyuki ; Franks, Paul W. ; North, Kathryn N. ; Duijn, C.M. Van; Mather, Karen A. ; Hansen, Torben ; Hansson, Ola ; Spector, Tim D. ; Murabito, Joanne M. ; Richards, J.B. ; Rivadeneira, Fernando ; Langenberg, Claudia ; Perry, John R.B. ; Wareham, Nick J. ; Scott, Robert A. ; Oei, Ling ; Zheng, Hou Feng ; Forgetta, Vincenzo ; Leong, Aaron ; Ahmad, Omar S. ; Laurin, Charles ; Mokry, Lauren E. ; Ross, Stephanie ; Elks, Cathy E. ; Bowden, Jack ; Warrington, Nicole M. ; Murray, Anna ; Ruth, Katherine S. ; Tsilidis, Konstantinos K. ; Medina-Gómez, Carolina ; Estrada, Karol ; Bis, Joshua C. ; Chasman, Daniel I. ; Demissie, Serkalem ; Enneman, Anke W. ; Hsu, Yi Hsiang ; Ingvarsson, Thorvaldur ; Kähönen, Mika ; Kammerer, Candace ; Lacroix, Andrea Z. ; Li, Guo ; Liu, Ching Ti ; Liu, Yongmei ; Lorentzon, Mattias ; Mägi, Reedik ; Mihailov, Evelin ; Milani, Lili ; Moayyeri, Alireza ; Nielson, Carrie M. ; Sham, Pack Chung ; Siggeirsdotir, Kristin ; Sigurdsson, Gunnar ; Stefansson, Kari ; Trompet, Stella ; Thorleifsson, Gudmar ; Vandenput, Liesbeth ; Velde, Nathalie Van Der; Viikari, Jorma ; Xiao, Su Mei ; Zhao, Jing Hua ; Evans, Daniel S. ; Cummings, Steven R. ; Cauley, Jane ; Duncan, Emma L. ; Groot, Lisette C.P.G.M. De; Esko, Tonu ; Gudnason, Vilmundar ; Harris, Tamara B. ; Jackson, Rebecca D. ; Jukema, J.W. ; Ikram, Arfan M.A. ; Karasik, David ; Kaptoge, Stephen ; Kung, Annie Wai Chee ; Lehtimäki, Terho ; Lyytikäinen, Leo Pekka ; Lips, Paul ; Luben, Robert ; Metspalu, Andres ; Meurs, Joyce B. van; Minster, Ryan L. ; Orwoll, Erick ; Oei, Edwin ; Psaty, Bruce M. ; Raitakari, Olli T. ; Ralston, Stuart W. ; Ridker, Paul M. ; Robbins, John A. ; Smith, Albert V. ; Styrkarsdottir, Unnur ; Tranah, Gregory J. ; Thorstensdottir, Unnur ; Uitterlinden, Andre G. ; Zmuda, Joseph ; Zillikens, M.C. ; Ntzani, Evangelia E. ; Evangelou, Evangelos ; Ioannidis, John P.A. ; Evans, David M. ; Ohlsson, Claes - \ 2017
Nature Communications 8 (2017). - ISSN 2041-1723
Hand grip strength is a widely used proxy of muscular fitness, a marker of frailty, and predictor of a range of morbidities and all-cause mortality. To investigate the genetic determinants of variation in grip strength, we perform a large-scale genetic discovery analysis in a combined sample of 195,180 individuals and identify 16 loci associated with grip strength (P<5 × 10-8) in combined analyses. A number of these loci contain genes implicated in structure and function of skeletal muscle fibres (ACTG1), neuronal maintenance and signal transduction (PEX14, TGFA, SYT1), or monogenic syndromes with involvement of psychomotor impairment (PEX14, LRPPRC and KANSL1). Mendelian randomization analyses are consistent with a causal effect of higher genetically predicted grip strength on lower fracture risk. In conclusion, our findings provide new biological insight into the mechanistic underpinnings of grip strength and the causal role of muscular strength in age-related morbidities and mortality.
Scaling, similarity, and the fourth paradigm for hydrology
Peters-Lidard, Christa D. ; Clark, Martyn ; Samaniego, Luis ; Verhoest, Niko E.C. ; Emmerik, Tim Van; Uijlenhoet, Remko ; Achieng, Kevin ; Franz, Trenton E. ; Woods, Ross A. - \ 2017
Hydrology and Earth System Sciences 21 (2017)7. - ISSN 1027-5606 - p. 3701 - 3713.
In this synthesis paper addressing hydrologic scaling and similarity, we posit that roadblocks in the search for universal laws of hydrology are hindered by our focus on computational simulation (the third paradigm) and assert that it is time for hydrology to embrace a fourth paradigm of data-intensive science. Advances in information-based hydrologic science, coupled with an explosion of hydrologic data and advances in parameter estimation and modeling, have laid the foundation for a data-driven framework for scrutinizing hydrological scaling and similarity hypotheses. We summarize important scaling and similarity concepts (hypotheses) that require testing; describe a mutual information framework for testing these hypotheses; describe boundary condition, state, flux, and parameter data requirements across scales to support testing these hypotheses; and discuss some challenges to overcome while pursuing the fourth hydrological paradigm. We call upon the hydrologic sciences community to develop a focused effort towards adopting the fourth paradigm and apply this to outstanding challenges in scaling and similarity.
The evolution of process-based hydrologic models : Historical challenges and the collective quest for physical realism
Clark, Martyn P. ; Bierkens, Marc F.P. ; Samaniego, Luis ; Woods, Ross A. ; Uijlenhoet, Remko ; Bennett, Katrina E. ; Pauwels, Valentijn R.N. ; Cai, Xitian ; Wood, Andrew W. ; Peters-Lidard, Christa D. - \ 2017
Hydrology and Earth System Sciences 21 (2017)7. - ISSN 1027-5606 - p. 3427 - 3440.
The diversity in hydrologic models has historically led to great controversy on the "correct" approach to process-based hydrologic modeling, with debates centered on the adequacy of process parameterizations, data limitations and uncertainty, and computational constraints on model analysis. In this paper, we revisit key modeling challenges on requirements to (1) define suitable model equations, (2) define adequate model parameters, and (3) cope with limitations in computing power. We outline the historical modeling challenges, provide examples of modeling advances that address these challenges, and define outstanding research needs. We illustrate how modeling advances have been made by groups using models of different type and complexity, and we argue for the need to more effectively use our diversity of modeling approaches in order to advance our collective quest for physically realistic hydrologic models.
Growth performance and body composition of broilers affected by exchange of dietary fat by starch
Veldkamp, Teun ; Dekker, Ruud ; Harn, Jan van; Smit-Heinsbroek, A. ; Lee, A. Van der; Jansman, Alfons - \ 2017
In: Proceedings of the 21st European Symposium on Poultry Nutrition. - Wageningen : Wageningen Academic Publishers - ISBN 9789086863068 - p. 169 - 169.
Dietary composition such as the concentrations of protein/amino acids, fat, and starch+sugar and their ratio, may affect the post-absorptive metabolism of energy, and protein and energy deposition in the body. In a 2×3 factorial block design, the effects of two dietary crude protein (CP) concentrations (high protein (HP) vs low protein (LP); 200/190 vs 170/160 g/kg in grower and finisher phase, respectively) and three dietary fat/starch concentrations (high fat (HF); fat and starch 120 and 350 g/kg, respectively, medium fat (MF); fat and starch 80 and 425 g/kg, respectively and low fat (LF); fat and starch 40 and 500 g/kg, respectively) in iso-energetic diets on the growth performance and body composition of Ross 308 broilers were studied (8 to 38 d). Overall, body weight gain (BWG) of broilers fed HP diets was significantly higher than BWG of broilers fed LP diets (59.6 vs 58.3 g/d; P<0.001) and feed conversion ratio (FCR) of broilers fed HP diets was significantly lower than FCR of broilers fed LP diets (1.65 vs 1.68; P<0.05). BWG of broilers increased as starch concentration in the diet was increased (HF: 55.3 g/d, MF: 59.5 g/d and LF: 62.1 g/d; P<0.001). FCR of broilers improved significantly as the dietary concentration of starch increased and of fat decreased (HF: 1.74, MF: 1.69, LF: 1.57; P<0.001). CP digestibility (77 vs 64%; P<0.05) and protein depostion as proportion of CP intake (63 vs 56%; P<0.001) in broilers fed LF diets was significantly higher than in broilers fed HF diets. It was concluded that dietary energy source and protein level in iso-energetic diets balanced for first limiting essential amino acids influence growth performance and body composition of broilers.
Growth curve and diet density affect eating motivation, behaviour, and body composition of broiler breeders during rearing
Mozos, J. de los; Garcia Ruiz, A.I. ; Hartog, L.A. den; Villamide, M.J. - \ 2017
Poultry Science 96 (2017)8. - ISSN 0032-5791 - p. 2708 - 2717.
The aim of this work has been to assess the effect of diet density [control (CON) or 15% diluted (DIL)] and growth curve [recommended by the genetic line (RBW) or 15% heavier (HBW)] and their interaction on BW uniformity, feeding motivation, behavior, and body composition of broiler breeder pullets. A total of 3,000 one-day-old female breeders Ross 308, distributed in 20 pens, was randomly assigned to each treatment. Feed allowance was weekly adjusted to reach the desired BW. Feed was provided as pelleted (zero to 3 wk) and crumble (4 to 19 wk). Time eating was measured at 7, 11, and 19 weeks. A feeding rate test was performed after 11 weeks. Behavior was observed at 9 and 15 wk, by visual scan. At 6, 13, and 19 wk of age, one bird/pen was slaughtered for weighing different organs and analyzing the composition of empty whole bodies. Treatments did not affect BW uniformity; relative weights of the ovary, oviduct, or gizzard; or protein content of empty BW. Time eating varied with the growth curve at 19 wk (P < 0.05), HBW pullets spent 19 more min eating than RBW pullets. DIL led to 4 and 8 more min eating at 19 wk for pullets of RBW and HBW (P < 0.05), respectively. Pullets fed DIL consumed 30% (P < 0.05) less during the feeding rate test when kept on a restricted regimen, and they had lower compensatory energy intake after ad libitum feeding than those fed CON, indicating lower feeding motivation. Behavior was affected by the age and by the time of the d measured, but it did not change with the treatments. Birds spent most time pecking objects (50%), feeding (28%), and drinking (17%). Pullets fed DIL had 8% lower breast yield at different ages and higher empty digestive tracts at 6 weeks. Body composition varied with age; fat content increased from 12.7 to 15.9 to 19.8% for 6, 13, and 19 wk, respectively. The lowest body fat was observed for RBW pullets fed DIL (P = 0.003) at 19 weeks. Feeding DIL diets to HBW pullets could be done to increase the time spent eating and reduce their feeling of hunger without negative effects on body composition. However, its influence on behavior and BW uniformity was not proved.
Stadium Coltan : artisanal mining, reforms and social change in eastern Democratic Republic of Congo
Wakenge, Claude Iguma - \ 2017
University. Promotor(en): Thea Hilhorst, co-promotor(en): K. Vlassenroot; Jeroen Cuvelier. - Wageningen : Wageningen University - ISBN 9789463434560 - 210
mining - conflict - economic sociology - cooperatives - reconstruction - poverty - rural sociology - workers - feedstocks - minerals - congo democratic republic - central africa - mijnbouw - economische sociologie - coöperaties - reconstructie - armoede - rurale sociologie - werkers - industriële grondstoffen - mineralen - democratische republiek kongo - centraal-afrika

In the Democratic Republic of Congo (DRC), the mining sector has the potential to play a pivotal role in post-conflict reconstruction (World Bank, 2008), and artisanal mining sustains the livelihoods of millions people in the country (PACT, 2010). However, in the last 15 years, minerals from this artisanal mining have been ill-reputed. Eastern DRC has often been characterised by chronic instability and violent conflicts (Autesserre, 2010; Stearns, 2011) because it is widely believed that minerals in this region have attracted the greed of national and foreign armed groups, who benefit from the mining business.

Although this ‘greed hypothesis’ has been criticised for its inconsistent performance in explaining resource-related conflicts (Le Billon, 2010; Ross, 2006), various national and international reform initiatives have gained momentum (Verbruggen et al., 2011). These initiatives aim to make the Congolese artisanal mining sector more transparent and to prevent ‘conflict minerals’ from entering the international market. In 2014, 13 reform initiatives—10 focusing on 3T (tantalum, tin and tungsten) and three on gold—were operational in eastern DRC (Cuvelier et al. 2014: 5). The implicit assumptions are that mining reforms will fully ‘clean’ artisanal mining of violence and corruption and that this will contribute to sustaining people’s livelihoods (Garrett and Mitchell, 2009: 12).

This study investigated initiatives intended to ‘formalise’ artisanal mining in DRC—in other words, they aimed to bring mining under state control. The study especially focuses on the effects of one among these initiatives—the ITRI Tin Supply Chain Initiative (iTSCi)—on two groups of actors: miners (creuseurs) and middlemen (négociants). This thesis thus presents a fine-grained case study of the iTSCi. Designed by the International Tin Research Institute in 2009, iTSCi provides a means of determining the origin of 3T and documenting the trading chain for these minerals by ‘tagging and bagging’ the loads of 3T near miners’ shafts (at postes d’achat/selling points or buying stations), at counting offices (comptoirs) and in mineral depots, before the minerals are exported through the international market.

This is a qualitative study undertaken at three coltan mining sites of northern Katanga: Kahendwa, Kisengo and Mai-Baridi. Coltan has been extracted at these sites since 2007. From March 2013 to September 2014, data were collected using participant observation of people’s practices (extraction/sale of coltan and various types of interactions between trading houses, cooperatives, mineworkers (creuseurs) and middlemen (négociants), as well as detailed in-depth interviews with creuseurs, négociants and their households. Data were also collected from the staff of mining cooperatives, trading houses, state authorities and civil servants—predominantly of the Service d’Assistance et d’Encadrement du Small-Scale Mining (SAESSCAM) and the Division des Mines. The last group of informants were a group of clandestine coltan négociants (known as hiboux—literally, ‘owls’), who were followed in the study.

The purpose of this research is to study the micro-dynamics of changes after the reforms following the implementation of iTSCi. The study thus provides insights into how iTSCi is concretely implemented and how it has altered the organisation of mining and the trade of coltan. The study also aims to examine how this organisation affected creuseurs and négociants. The main research question of this study is as follows:

How have initiatives to reform artisanal mining (iTSCi in particular) affected institutional change, how does this relate to changes in patterns of coltan production and trade, how were creuseurs and négociants affected by these changes, and how did these groups respond in the coltan mining areas of Kahendwa, Kisengo and Mai Baridi (northern Katanga) from 2009 to 2014?

Analytically, the study adopted three main theoretical perspectives. First, an actor-oriented approach was taken, building on the premise that individual actors have the agency, knowledge and experience to reflect upon their situation and to respond to changes in their surrounding context (Giddens, 1984). Although the examined mining reforms consist predominantly of ‘ready-made’ techniques such as iTSCi’s ‘tagging and bagging’, analysing reforms with an actor orientation helps to highlight people’s reactions and responses. This includes how reform policies are applied in institutions (e.g. mining cooperatives), how they interact, how they are assigned meaning and how they are negotiated by social actors (Christoplos and Hilhorst, 2009).

Second, the study builds on the sociology of economic life, which holds that economic action is a form of social action that is socially ‘embedded’, meaning that it is linked with or dependent on actions and institutions (such as social networks) that are noneconomic in content, goals and processes (Granovetter, 2005). This perspective facilitates the analysis of the livelihoods of négociants, including mechanisms of smuggling minerals into and beyond the mining areas where iTSCi is in force.

Third, this thesis introduced the original concept of ‘enclaves of regulations’. These enclaves refer to the mining areas where iTSCi or other reforms are in force. This thesis has shown that, although these ‘enclaves’ appear to be ‘closed’ and insulated from the environment in terms of the locally applied rules for the mining and trading of minerals (e.g. ‘tagging and bagging’), in reality, such closure is not complete. This thesis has demonstrated that it would therefore be more appropriate to consider these ‘enclaves’ as semi-autonomous fields with porous boundaries.

Apart from the introduction and the concluding chapters, this thesis is composed of five chapters. Chapter 2 explores the evolution of the mineral sector in the Katanga province. It analyses the history of mining, the initiation of artisanal mining and how the ongoing reforms have been informed by this history. In this chapter, it is shown that there is a long history of the organisation of mining in the Katangese province. The reforms therefore did not enter into a stage of anarchy, or an institutional void, but they added a layer to already existing forms of organisation.

Chapter 3 focuses on mining cooperatives as newly introduced institutions aimed at governing the artisanal mining sites. Through a single case study, the chapter analyses how these cooperatives —especially the Coopérative des Artisanaux Miniers du Congo, CDMC—were introduced into the mining areas and how they interacted and blended with pre-existing miners’ organisations. This chapter demonstrates that cooperatives have been an emergent—rather than durable—solution in terms of representing the interests of artisanal miners.

In Chapter 4, I provide a different perspective on ‘conflict minerals’. I thus introduce the notion of ‘reform conflicts’ to emphasise that, although ongoing reforms aim to sever the supposed linkages between the artisanal mining business and violent conflicts, these reforms have become a driving force behind the emergence of new conflicts over property rights and access to minerals.

Chapter 5 is about livelihoods. It analyses how the reforms have influenced the livelihoods and socioeconomic position of négociants. This chapter also explores what kind of opportunities the reforms have offered to this group of mineral brokers often considered powerful in the mineral supply chain and explains what kind of constraints the négociants have confronted and why they have opted to diversify their livelihood portfolios. The chapter has shown that the reforms have affected this group of mineral brokers in different ways. Some négociants were well off, whereas others have been excluded from the mineral commodity chain. These findings contradict the widespread opinion that négociants are always abusive brokers in the mineral production and commodity chain.

Chapter 6 analyses the responses of creuseurs and négociants to iTSCi. Although the mining sites where iTSCi is in force appear to be ‘enclaves of regulations’, I explore the strategies of creuseurs and négociants to bypass iTSCi and the reforms, especially around the coltan trade. This chapter demonstrates that coltan smuggling is a deeply rooted practice. Despite the reforms, smuggling continues in different forms.

All of the elements highlighted above suggest that mining reforms have undergone a major shift, from addressing the initial problems associated with ‘conflict minerals’ to creating or reinforcing various types of problems, such as the influence of ‘big men’ in the mining business, coltan smuggling and the emergence of new conflicts over accessing minerals. This means that reform initiatives such as iTSCi should be based on knowledge about the actual situation. Thus, understanding and addressing these new types of problems calls for a comprehensive approach at both local and broader levels.

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