Staff Publications

Staff Publications

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

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

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

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    Combining food-based dietary recommendations using Optifood with zinc-fortified water potentially improves nutrient adequacy among 4- to 6-year-old children in Kisumu West district, Kenya
    Kujinga, Prosper ; Borgonjen-van den Berg, Karin J. ; Superchi, Cecilia ; Hove, Hermine J. ten; Onyango, Elizabeth Opiyo ; Andang'o, Pauline ; Galetti, Valeria ; Zimmerman, Michael B. ; Moretti, Diego ; Brouwer, Inge D. - \ 2018
    Maternal and Child Nutrition 14 (2018)2. - ISSN 1740-8695
    children - diets - Optifood - water - zinc
    Children in developing countries often face multiple micronutrient deficiencies. Introduction of zinc-fortified water can increase zinc intake, but additional recommendations are required to address overall diet nutrient adequacy. We developed and tested food-based recommendations (FBRs) that included zinc-fortified water for children aged between 4 and 6 years from rural Kenya to achieve the best possible nutrient adequacy. Dietary intakes of 60 children aged 4–6 years, from Kisumu West district, Kenya, were assessed using a quantitative multipass 24-hr recall. Linear programming model parameters were derived, including a list of foods consumed, median serving sizes, and distribution of frequency of consumption. By using the Optifood linear programming tool, we developed FBRs for diets including zinc-fortified water. FBRs with nutrient levels achieving ≥70% recommended nutrient intake (RNI) of the World Health Organization/Food and Agriculture Organization of the United Nations RNI for most of the 12 considered nutrients were selected as the final recommendations for the children. With no FBRs and no zinc-fortified water, percent RNI coverage range was between 40% and 76% for zinc, improving to 66–101% after introduction of zinc-fortified water. The final set of FBRs achieved nutrient adequacy for all nutrients except for vitamin A (25% RNI) and folate (68% RNI). Introduction of zinc-fortified water combined with FBRs will likely improve the nutrient adequacy of diets consumed by children in Kenya but needs to be complemented with alternative interventions to ensure dietary adequacy.
    Smaakmissie vlees, vis en vervangers : Handleiding groep 5-6
    Vernooij, Annelou ; Top, R. van den - \ 2016
    Steunpunt Smaaklessen
    nutrition - children - health - feeding habits - diets - teaching materials
    Mitchel is een danser en hij organiseert een dansbootcamp voor kinderen. Nou krijgt hij ineens allerlei vragen van ouders over het eten tijdens de bootcamp. Vooral over vlees, vis, vega.. de eiwitten dus. Mitchel is erg druk met het bedenken van zijn moves en heeft dus helemaal geen tijd om dit uit te zoeken. Kunnen de leerlingen hem helpen om de juiste keuzes te maken en zorgen dat er informerende bordjes bij het buffet komen te staan? Ga op Smaakmissie! In deze Smaakmissie ontdekken leerlingen van alles over vlees, vis, peulvruchten ei en noten door zelf op onderzoek uit te gaan, zowel binnen als buiten de klas. De Smaakmissie bestaat uit 6 interactieve lessen met aanvullend een digibordmodule. Lees hier hoe de Smaakmissie werkt en ga aan de slag!
    Wat moet je doen en laten als je gezonder wilt
    Witkamp, R.F. - \ 2015
    Universiteit van Nederland
    diëten - voeding en gezondheid - voedselwetenschappen - fysiologie - voedselproducten - gezondheidsvoedsel - gezondheidsbevordering - voedingsonderzoek - diets - nutrition and health - food sciences - physiology - food products - health foods - health promotion - nutrition research
    Slik jij de praatjes van afslankguru's als zoete koek? Ken jij alle diëten uit je hoofd? Renger Witkamp, hoogleraar Voeding en Farmacologie (Wageningen UR) bekijkt al deze hypes met een nuchtere en wetenschappelijke blik. Na dit praatje kun je alles wat je voorgeschoteld krijgt in de media over je gezondheid beter in perspectief plaatsen.
    Microalgae diets for landbased aquaculture of the cockle Cerastoderma edule: impacts of dietary fatty acids on growth
    Reis Batista, I.C. dos - \ 2015
    Wageningen University. Promotor(en): Aad Smaal, co-promotor(en): Johan Kamermans; R.H. Wijffels. - Wageningen : Wageningen University - ISBN 9789462575875 - 132
    schaaldieren - schaal- en schelpdierenteelt - algen - voedering - voersamenstelling - diëten - vetzuren - groei - tanks - plassen - aquacultuur - shellfish - shellfish culture - algae - feeding - feed formulation - diets - fatty acids - growth - tanks - ponds - aquaculture

    Land-based shellfish culture as a part of a multi-trophic aquaculture systems has yet to be implemented in Europe. Recently the pilot project Zeeuwse Tong (The Netherlands) evaluated the feasibility of a system of fish (Dover sole), ragworms, phytoplankton and bivalves. This thesis focused on the dietary fatty acids impact on growth, survival and fatty acid composition of juveniles (shell length >5mm) of the common cockle Cerastoderma edule, for land-based culture.

    Dietary fatty acids were chosen as the main nutritional research subject given the existing literature indicating their importance for reproduction, and growth and survival of larvae, post-larvae, spat and seed of most bivalves. However, since grow-out of juvenile cockles in land-based aquaculture is not common, no information is available on the dietary fatty acid requirements of juveniles. To determine if the presence of specific fatty acids is more important for growth and survival of juvenile cockles than the total amount of dietary fatty acids supplied, least cost linear programming was used to design live microalgae diets. Monocultures of indigenous algae were grown under controlled conditions and sampled to determine their quality in terms of dry weight, organic matter, lipid and fatty acids composition. These differences in biochemical composition of the microalgae were used in a least-cost programming software, and allowed the formulation of three diets with different fatty acid contents, but similar dry weight, organic matter, lipid and total fatty acid content. The formulated diets were then used to determine the importance of dietary fatty acids for growth, survival and fatty acid composition of juvenile cockles (Cerastoderma edule). Juvenile cockles (6.24±0.04 mm) were constantly fed live microalgal diets with similar lipid, organic matter and total fatty acid contents but different individual fatty acid concentrations: high-EPA, no-DHA and low-ARA diets. Growth was positively affected by high-EPA and low-ARA diets, whereas no significant growth was observed for the no-DHA diet. However, high mortality of cockles fed no-DHA diet and the low absorption efficiency and clearance rate of this diet indicate that this diet is unsuitable for juvenile cockles. In balanced diets with EPA and DHA, lower concentrations of ARA did not limit growth. The combination of EPA and DHA in a live microalgae diet was beneficial for the growth and survival of juvenile cockles, but no conclusion on the importance of supplying only EPA could be made. To address this, an additional growth experiment was designed. Growth and fatty acid profiles of juveniles cockles were determined after 28 days of feeding diets:1) with EPA 2) with DHA; 3) with EPA and DHA from a mixture of a diatom with a green algae; 4) with EPA and DHA from a mixture of the two green algae and 5) without long-chain (>C20) fatty acids. Significantly higher growth rate was observed with the treatment rich in EPA, while the lowest growth rates were found in without EPA. These results indicate that EPA is necessary for the short-term growth of cockles. Moreover, the fatty acid profile of the polar lipids confirmed that, like most marine invertebrates, juvenile C. edule are not able to biosynthesize EPA and DHA from 18:3n-3 but are capable of biosynthesizing diene and triene NMI fatty acids. The occurrence of the NMI fatty acids was diet related, thus refuting the possibility of production of NMI as replacement for EPA and DHA.

    Furthermore, in order to develop land-based culture of cockles it is crucial to have a supply of high quality live microalgal diets produced with minimum effort. Therefore, the use of simplified microalgae media, with different nitrogen sources (nitrate or ammonium) and molar N:P ratio, phosphorus, silica, iron, manganese and vitamins were also investigated. Chaetoceros muelleri, a marine diatom that was chosen given its robustness and quality as food for juvenile cockles, reacted positively to all simplified media. At the exponential phase, all cultures had reached similar cellular concentrations and dry weight productions. Cultures grown on ammonium media had a longer cultivation period, 20 days. Considering dry-weight production, culture duration, nutrient efficiency and lipid composition, the simplified media containing ammonium, phosphorus, silica, iron, manganese and vitamins proved to be a viable choice for batch culture of C. muelleri. The choice between these two media depends on the final purpose of the microalgae cultures and whether lipid contents (NH49:1), dry weight biomass (NH425:1) or nitrogen input and output (NH49:1) are more important.

    In this thesis it was demonstrated that mono-algal diets with high EPA, as well as mixed live microalgae diets with high EPA and DHA contents proved to be suitable diets for C. edule juveniles. In addition, a positive relation between growth and the amount fed was found. The growth rates of the cultured cockles in this thesis are in accordance with the rates observed under natural conditions. The use of the simplified microalgae culture medium tested represents a significant decrease in the cost and preparation of the medium, as well as longer production and harvest periods, while maintaining microalgae quality. These results indicate that land-based aquaculture of cockles and microalgae is therefore a promising venture, with potential for expansion.

    Improving the feeding value of straws with Pleurotus ostreatus
    Khan, N.A. ; Hussain, S. ; Ahmad, N. ; Alam, S. ; Bezabhi, M. ; Hendriks, W.H. ; Yu, P. ; Cone, J.W. - \ 2015
    Animal Production Science 55 (2015)2. - ISSN 1836-0939 - p. 241 - 245.
    chemical-composition - wheat-straw - digestibility - fermentation - diets - fiber
    The high content of lignin in cell walls is the major limiting factor in the digestion and utilisation of cereal crop residues by ruminants. The aim of this study was to evaluate the effectiveness of the white rot fungus, Pleurotus ostreatus (P. ostreatus), to degrade lignin and to enhance the rumen degradability of maize stover, rice straw, wheat straw and their mixture in equal proportion on a dry-matter (DM) basis. Four samples of each substrate were incubated aerobically in triplicate with P. ostreatus for 0 (Control), 21, 28 and 35 days under solid-state conditions (temperature, 24°C; humidity, 70 ± 5%). The changes in chemical composition, DM and nutrient losses, and rumen fermentation characteristics using in vitro DM digestibility (DMD) and the in vitro gas-production (GP) technique were measured. The results showed that incubation with P. ostreatus decreased (P <0.001) the contents of neutral detergent fibre and lignin with a concomitant increase (P <0.001) in the contents of ash and crude protein. The losses of nutrients differed (P <0.001) among the straw types, with rice straw and maize stover showing the largest (P <0.05) lignin degradation compared to wheat and mixed straws. The DMD and 72-h cumulative GP increased (P <0.001) consistently with increasing fungal incubation period and for all substrates the highest values of DMD and GP were measured after 35 days of incubation with P. ostreatus. The lignin degradation was strongly associated with hemicellulose degradation (r = 0.71) across the various straws. Results of the present study demonstrated that incubation of low-quality crop residues with P. ostreatus under solid-state conditions upgrades their feeding value by reducing the content of lignin and increasing the content of crude protein and ruminal degradation.
    Economic values of growth and feed efficiency for fish farming in recirculating aquaculture system with density and nitrogen output limitations: a case study with African catfish (Clarias gariepinus)
    Besson, M. ; Komen, H. ; Aubin, J. ; Boer, I.J.M. de; Poelman, M. ; Quillet, E. ; Vancoillie, C. ; Vandeputte, M. ; Arendonk, J.A.M. van - \ 2014
    Journal of Animal Science 92 (2014)12. - ISSN 0021-8812 - p. 5394 - 5405.
    salmon salmo-salar - rainbow-trout - oncorhynchus-mykiss - selection - diets - weights
    In fish farming, economic values (EV) of breeding goal traits are lacking, even though they are key parameters when defining selection objectives. The aim of this study was to develop a bioeconomic model to estimate EV of 2 traits representing production performances in fish farming: the thermal growth coefficient (TGC) and the feed conversion ratio (FCR). This approach was applied to a farm producing African catfish (Clarias gariepinus) in a recirculating aquaculture system (RAS). In the RAS, 2 factors could limit production level: the nitrogen treatment capacity of the biofilter or the fish density in rearing tanks at harvest. Profit calculation includes revenue from fish sales, cost of juveniles, cost of feed, cost of waste water treatment, and fixed costs. In the reference scenario, profit was modeled to zero. EV were calculated as the difference in profit per kilogram of fish between the current population mean for both traits (µt) and the next generation of selective breeding (µt + ¿t) for either TGC or FCR. EV of TGC and FCR were calculated for three generations of hypothetical selection on either TGC or FCR (respectively 6.8% and 7.6% improvement per generation). The results show that changes in TGC and FCR can affect both the number of fish that can be stocked (number of batches per year and number of fish per batch) and the factor limiting production. The EV of TGC and FCR vary and depend on the limiting factors. When dissolved NH3-N is the limiting factor for both µt and µt + ¿t, increasing TGC decreases the number of fish that can be stocked but increases the number of batches that can be grown. As a result, profit remains constant and EVTGC is zero. Increasing FCR, however, increases the number of fish stocked and the ratio of fish produced per kilogram of feed consumed (“economic efficiency”). The EVFCR is 0.14 €/kg of fish, and profit per kilogram of fish increases by about 10%. When density is the limiting factor for both µt and µt + ¿t, the number of fish stocked per batch is fixed; therefore, extra profit is obtained by increasing either TGC, which increases the annual number of batches, or by decreasing FCR, which decreases annual feed consumption. EVTGC is 0.03 €/kg of fish and EVFCR is 0.05–0.06 €/kg of fish. These results emphasize the importance of calculating economic values in the right context to develop efficient future breeding programs in aquaculture.
    Evaluation of free water and water activity measurements as functional alternatives to total moisture content in broiler excreta and litter samples
    Hoeven-Hangoor, E. van der; Rademaker, C. ; Paton, N.D. ; Verstegen, M.W.A. ; Hendriks, W.H. - \ 2014
    Poultry Science 93 (2014)7. - ISSN 0032-5791 - p. 1782 - 1792.
    sugar-beet pulp - gastrointestinal-tract - oat hulls - nonstarch polysaccharides - growth-performance - poultry houses - low-viscosity - chickens - ammonia - diets
    Litter moisture contents vary greatly between and within practical poultry barns. The current experiment was designed to measure the effects of 8 different dietary characteristics on litter and excreta moisture content. Additionally, free water content and water activity of the excreta and litter were evaluated as additional quality measures. The dietary treatments consisted of nonstarch polysaccharide content (NSP; corn vs. wheat), particle size of insoluble fiber (coarse vs. finely ground oat hulls), viscosity of a nonfermentable fiber (low- and high-viscosity carboxymethyl cellulose), inclusion of a clay mineral (sepiolite), and inclusion of a laxative electrolyte (MgSO4). The 8 treatments were randomly assigned to cages within blocks, resulting in 12 replicates per treatment with 6 birds per replicate. Limited effects of the dietary treatments were noted on excreta and litter water activity, and indications were observed that this measurement is limited in high-moisture samples. Increasing dietary NSP content by feeding a corn-based diet (low NSP) compared with a wheat-based diet (high NSP) increased water intake, excreta moisture and free water, and litter moisture content. Adding insoluble fibers to the wheat-based diet reduced excreta and litter moisture content, as well as litter water activity. Fine grinding of the oat hulls diminished the effect on litter moisture and water activity. However, excreta moisture and free water content were similar when fed finely or coarsely ground oat hulls. The effects of changing viscosity and adding a clay mineral or laxative deviated from results observed in previous studies. Findings of the current experiment indicate a potential for excreta free water measurement as an additional parameter to assess excreta quality besides total moisture. The exact implication of this parameter warrants further investigation.
    Characterization of Phosphorus in Animal Manures Collected from Three (Dairy, Swine, and Broiler) Farms in China
    Li, G. ; Li, H. ; Leffelaar, P.A. ; Shen, J. ; Zhang, F. - \ 2014
    PLoS ONE 9 (2014)7. - ISSN 1932-6203
    magnetic-resonance-spectroscopy - enzymatic-hydrolysis - organic phosphorus - northwest germany - poultry litter - forms - soil - diets - speciation - fractions
    In order to identify the phosphorus species and concentration in animal manure, we comparatively characterized phosphorus in dairy manure, swine manure, and broiler litter, using a sequential procedure, a simplified two-step procedure (NaHCO3/NaOH+EDTA), and a solution Phosphorus-31 Nuclear Magnetic Resonance (31P-NMR) spectroscopy procedure. In the sequential procedure, deionized water extracted 39, 22, and 32%; NaHCO3 extracted 48, 26, and 37%; NaOH extracted 8, 9, and 13.8%; and HCl extracted 3, 42.8, and 17% of the total phosphorus in dairy manure, swine manure and broiler litter, respectively. Total phosphorus extracted by the NaHCO3/NaOH+EDTA procedure was 7.5, 32.4, and 15.8 g P kg-1 for dairy manure, swine manure, and broiler litter, respectively. The solution 31P-NMR procedure detected that 9, 34, and 29% of total phosphorus was phytic acid in dairy manure, swine manure, and broiler litter, respectively. These results show that phosphorus forms, availability, and quantities differ between animal manures, which provides valuable information for P characterization of animal manures in China.
    Effects of polysaccharide from fruiting bodies of Agaricus bisporus, Agaricus brasiliensis, and Phenllinus linteus on alcoholic liver injury
    Uyanoglu, M. ; Canbek, M. ; Griensven, L.J.L.D. van; Yamac, M. ; Senturk, H. ; Kartkaya, K. ; Oglakci, A. ; Turgak, O. ; Kanbak, G. - \ 2014
    International Journal of Food Sciences and Nutrition 65 (2014)4. - ISSN 0963-7486 - p. 482 - 488.
    permeability transition pore - ethanol-induced apoptosis - rats - disease - mushrooms - diets
    In the present study, the curative effects of crude polysaccharides (PSs) from mushrooms on the symptoms of alcoholic liver injury were investigated. PSs from Agaricus bisporus, Agaricus brasiliensis, and Phellinus linteus fruiting bodies were administered by gavage at levels of 100¿mg per kg body weight per day for 7¿d after the onset of the disease. The caspase-3 activity, mitochondrial membrane potential, mitochondrial outer membrane integrity of the liver tissues of sacrificed rats, and the serum alanine aminotransferase (ALT) levels were determined. In addition, light and transmission electron microscope (TEM) studies were performed for histopathological and cytological evaluations on liver sections. PSs from A. brasiliensis decreased ALT level and mitochondrial membrane potential and increased the outer membrane integrity; microscopic examinations also revealed normal hepatocytes and tissue. On the basis of our data, it can be argued that crude PSs from Agaricus brasiliensis have therapeutic potential for alcoholic liver injury.
    Effect of a prebiotic on performance of partridge
    Khaksar, V. ; Veldkamp, T. ; Hashemipour, H. - \ 2014
    Journal of Animal Physiology and Animal Nutrition 98 (2014)3. - ISSN 0931-2439 - p. 511 - 516.
    blood parameters - young turkeys - diets - supplementation - fermacto-500 - methionine - carcass - quail
    An experiment was conducted to investigate the effect of a prebiotic on performance of partridge. The experiment was carried out with a total of eighty-day-old male Chukar partridge (Alectoris chukar chukar) chicks in a completely randomized design. The dietary treatments consisted of a control and an experimental treatment, and each treatment was replicated four times with 10 chicks per replicate. The experimental period lasted 16 weeks with a starter period (0–8 weeks) and a grower period (9–16 weeks). The control group was fed the basal diet, while the experimental group was fed the basal diet supplemented with 0.18% prebiotic Aspergillus meal in each period. Performance parameters included body weight gain, cumulative feed consumption and cumulative FCR and were recorded at biweekly intervals. Carcass characteristics and blood parameters were measured at the end of the experiment (week 16). Although the results showed that prebiotic had no significant effect on body weight gain and cumulative feed conversion ratio; however, the supplementation of Aspergillus meal significantly (p <0.05) decreased cumulative feed consumption. Also prebiotic significantly increased percentages of breast and gastrointestinal tract, decreased percentage of back-neck, decreased blood triglyceride and total cholesterol content and increased blood calcium content. From this study, it was concluded that dietary supplementation of 0.18% Aspergillus meal might offer beneficial effects on partridge feed consumption, carcass quality and blood cholesterol.
    Comparison of ileal and total tract nutrient digestibility of dry dog foods
    Hendriks, W.H. ; Thomas, G. ; Bosch, G. ; Fahey, G.C. - \ 2013
    Journal of Animal Science 91 (2013)8. - ISSN 0021-8812 - p. 3807 - 3814.
    amino-acid-composition - endogenous nitrogen - reactive lysine - protein - pigs - diets - bioavailability - ingredients - absorption - intestine
    The apparent total tract and ileal digestibility assays to measure AA absorption in commercial canine diets were compared in the present study. Five ileal cannulated dogs were fed 5 commercial dry canine foods selected to contain 19 to 30% CP in a 5 × 5 Latin square design. Ileal and total tract digestibility (apparent and standardized) of DM, OM, CP, crude fat (CF), carbohydrate, and AA (including reactive Lys) were calculated using Cr2O3 as an indigestible marker. Greater apparent total tract digestibility values were found for DM, OM, and CP (P = 0.034) compared with ileal digestibility values; however, CF (P = 0.058) had a greater ileal apparent digestibility. Apparent and standardized CP digestibility values were, respectively, 5.7 and 7.4 percentage units greater when measured over the total digestive tract compared with measurement at the ileum (P = 0.034 and 0.011, respectively). Ileal apparent digestibility for N of AA (P = 0.009) and most AA (P <0.05), except for Met, Ile, Lys, Phe, and Ala, was decreased if measured at the ileum. However, correction for endogenous losses showed only Met digestibility did not differ between measurement sites. Differences between sites in excess of 15 percentage units were recorded for AA. Apparent and standardized ileal reactive Lys digestibility was 3.1 to 15.3 percentage units greater than corresponding total tract digestibility values. For several indispensable AA, the bioavailability estimates currently used by the 2006 NRC and the 2011 Association of American Feed Control Officials to derive allowance estimates for canine adult maintenance were greater than the digestibility values of these AA in the commercial dog foods evaluated. Although the canine large intestine is relatively short, the total tract digestibility assay in dogs can overestimate the digestibility of dietary AA and CP and may not be an accurate method for the measurement of absorption. In this study, bioavailability estimates of AA appeared to be less than those used to derive allowance estimates for commercial dog foods. Further work is required if current recommendations warrant adjustment.
    Anti-methanogenic effects of monensin in dairy and beef cattle: A meta-analysis
    Appuhamy, J.A.D.R.N. ; Strathe, A.B. ; Jayasundara, S. ; Wagner-Riddle, C. ; Dijkstra, J. ; France, J. ; Kebreab, E. - \ 2013
    Journal of Dairy Science 96 (2013)8. - ISSN 0022-0302 - p. 5161 - 5173.
    controlled-release capsules - reduce methane emissions - enteric methane - nitrogen-utilization - milk-production - cows - steers - diets - performance - mitigation
    Monensin is a widely used feed additive with the potential to minimize methane (CH4) emissions from cattle. Several studies have investigated the effects of monensin on CH4, but findings have been inconsistent. The objective of the present study was to conduct meta-analyses to quantitatively summarize the effect of monensin on CH4 production (g/d) and the percentage of dietary gross energy lost as CH4 (Ym) in dairy cows and beef steers. Data from 22 controlled studies were used. Heterogeneity of the monensin effects were estimated using random effect models. Due to significant heterogeneity (>68%) in both dairy and beef studies, the random effect models were then extended to mixed effect models by including fixed effects of DMI, dietary nutrient contents, monensin dose, and length of monensin treatment period. Monensin reduced Ym from 5.97 to 5.43% and diets with greater neutral detergent fiber contents (g/kg of dry matter) tended to enhance the monensin effect on CH4 in beef steers. When adjusted for the neutral detergent fiber effect, monensin supplementation [average 32 mg/kg of dry matter intake (DMI)] reduced CH4 emissions from beef steers by 19 ± 4 g/d. Dietary ether extract content and DMI had a positive and a negative effect on monensin in dairy cows, respectively. When adjusted for these 2 effects in the final mixed-effect model, monensin feeding (average 21 mg/kg of DMI) was associated with a 6 ± 3 g/d reduction in CH4 emissions in dairy cows. When analyzed across dairy and beef cattle studies, DMI or monensin dose (mg/kg of DMI) tended to decrease or increase the effect of monensin in reducing methane emissions, respectively. Methane mitigation effects of monensin in dairy cows (–12 ± 6 g/d) and beef steers (–14 ± 6 g/d) became similar when adjusted for the monensin dose differences between dairy cow and beef steer studies. When adjusted for DMI differences, monensin reduced Ym in dairy cows (–0.23 ± 0.14) and beef steers (–0.33 ± 0.16). Monensin treatment period length did not significantly modify the monensin effects in dairy cow or beef steer studies. Overall, monensin had stronger antimethanogenic effects in beef steers than dairy cows, but the effects in dairy cows could potentially be improved by dietary composition modifications and increasing the monensin dose.
    Fishing for food : feeding ecology of harbour porpoises Phocoena phocoena and white-beaked dolphins Lagenorhynchus albirostris in Dutch waters
    Jansen, O.E. - \ 2013
    Wageningen University. Promotor(en): Peter Reijnders, co-promotor(en): Marten Scheffer. - S.l. : s.n. - ISBN 9789461734228 - 173
    phocoena - lagenorhynchus - dolfijnen - voedingsecologie - diëten - kustwateren - noordzee - oosterschelde - nederland - phocoena - lagenorhynchus - dolphins - feeding ecology - diets - coastal water - north sea - eastern scheldt - netherlands

    Harbour porpoises and white-beaked dolphins are the most common small cetaceans in the North Sea and Dutch coastal waters. The distribution and relative abundance of harbour porpoises and white-beaked dolphins from the Dutch coastal waters has changed significantly over the past decades. This thesis describes the past and present feeding ecology of these two species in Dutch coastal waters and investigates whether changes in abundance and relative distribution of porpoises reflect changes in their foodbase. For porpoises, three techniques for dietary analyses were combined, including stomach contents-, stable isotope- and fatty acid analysis, providing the most detailed description of their diet in time and space, elucidating differences between their short- and longer term diet.

    Stable isotope analysis (δ13C and δ15N) were carried out in bone and muscle samples collected from porpoises stranded along the Dutch coast. Muscle δ15N values revealed that neonatal enrichment occurred and that larger porpoises, in particular males, seem to feed on lower trophic level species, compared to smaller individuals. Also bone δ15N values show that larger animals had fed on lower trophic levels in distant times. Seasonal variation in bone δ15N and δ13C values revealed two distinct groups of porpoises along the Dutch coast, a winter group (mainly males) that migrated from neighbouring regions and a Dutch subpopulation in summer (Chapter 2).

    To assess the contribution of prey species to the porpoises’ diet, stable isotope analysis in both porpoise muscle and prey were carried out. With the use of a mixing model (Stable Isotope Analysis in R, SIAR), we revealed that 70-83% of the diet of porpoises consisted mainly of poor cod, mackerel, greater sandeel lesser sandeel, sprat and gobies. This highlights a higher importance of pelagic, schooling species in the porpoises’ diet compared to stomach contents, where 90.5% of the diet consisted of gobies, whiting, lesser sandeel, herring, cod and sprat. Porpoises thus also feed offshore on pelagic, schooling species, while they feed closer to shore on more benthic and demersal species shortly before they strand. This could be due to the distribution of prey species as well as differences in behaviour of porpoises and their prey between the coastal zone and offshore waters (Chapter 3).

    The use of Quantitative Fatty Acid Analysis (QFASA) showed that the diet of porpoises consisted mainly of gobies, mackerel, smelt, herring and dragonet, pointing towards profound differences between the diet as estimated by QFASA and as deduced from stomach contents. This study revealed that the longer term diet of porpoises in Dutch coastal waters consists both of coastal species (e.g. gobies, smelt and dragonet) and also pelagic, schooling species (e.g. mackerel and herring). The results also brought to dawn possible methodological problems in using QFASA for porpoise diet estimation, emphasizing the importance of applying different dietary analysis techniques when studying marine mammal diets and the need for controlled feeding experiments in order to improve the interpretation of dietary analysis results (Chapter 5).

    Besides new insights in the feeding ecology of porpoises, stable isotope analysis also elicited a non-food related conservation ecology issue. Distinct δ13C values in muscle of porpoises stranded in the Eastern Scheldt revealed that these porpoises foraged there for a longer period. This distinct δ13C signature of animals from the Eastern Scheldt was not observed in bone tissue, which suggests a relatively recent shift in habitat use rather than life-long residency of porpoises within the Eastern Scheldt. The high number of strandings within the Eastern Scheldt revealed a higher mortality rate compared to the Dutch coastal zone, indicating that along with other changes in the physical environment, the building of the storm surge barrier may play an important role in determining the residency of porpoises in the Eastern Scheldt, and that the area might act as an ecological trap for porpoises entering it. This is an example of the impact on marine species due to protection structures that emerge and respectively increase worldwide in response to the effects of global warming and climate change. It highlights that even semi-open structures, which are meant to ameliorate habitat loss, degradation and fragmentation, may still affect the abundance and distribution of migratory marine mammal species (Chapter 4).

    The analysis of stomach contents of white-beaked dolphins showed that their diet was dominated by Gadidae. All other prey species combined contributed little to the diet by weight. The two most important prey species based in weight were whiting and cod. In numbers, gobies were most common, but these contributed little to the diet by weight. The overall diet showed a lasting predominance of whiting and cod, without clear changes over time (35 years) or differences between sexes or size-classes of dolphins and revealed that white-beaked dolphins in the south-eastern North Sea are specialist feeders, with a strong preference for whiting and cod (Chapter 6).

    Stomach contents of juvenile white-beaked dolphins in our study revealed that at the age of about 1.5 years old, they had started feeding on solid food by taking a variety of small fish and invertebrate prey, mostly shrimp and squid. Immatures in our study, estimated to be 2-4 years old, still take small prey, including small gadoids, but also take larger gadoids. Calves apparently gradually learn to eat big fish by taking prey that is much smaller than those normally taken by their mothers. This study illustrates novel techniques for diet estimation to reconstruct sizes of shrimp and whiting from tail flaps and eye lenses, respectively (Chapter 7).

    Most dietary studies on porpoises and white-beaked dolphins are deduced from stomach contents. This thesis has demonstrated that using indirect methods for studying the feeding ecology of marine mammals is a valuable addition to the more direct approach using stomach contents. It supports the need for multi-method approaches because by using only one technique, key prey species in the predator-prey relation may be missed or underestimated. Future ecological and fishery impact assessment studies and management decisions for the conservation of porpoises and white-beaked dolphins should acknowledge a difference between their long- and short-term diet. Large improvement in the interpretation of the results from diet analyses can be established either by controlled feeding experiments with animals in captivity or by studies that help to understand the common principals in dietary analyses (e.g. digestion rates, turnover rates of tissues, tissue-dependent isotopic fractionation between predator and prey and lipid metabolism within the animal) and variation of these between species.

    d13C as a marker to study digesta passage kinetics in ruminants: a combined in vivo and in vitro study
    Pellikaan, W.F. ; Verstegen, M.W.A. ; Tamminga, S. ; Dijkstra, J. ; Hendriks, W.H. - \ 2013
    Animal 7 (2013)5. - ISSN 1751-7311 - p. 754 - 767.
    neutral detergent fiber - dairy-cows - internal markers - grass silages - particle-size - rumen - cattle - diets - digestibility - concentrate
    The aim of the current study was to explore the use of the tracer 13C as an internal marker to assess feed fraction-specific digesta passage kinetics through the digestive tract of dairy cows. Knowledge on feed-specific fractional passage rates is essential to improve estimations on the extent of rumen degradation and microbial protein efficiency; however, this information is largely lacking. An in vivo and in vitro experiment was conducted with grass silages (Lolium perenne L.) that were enriched with 13C by growing the grass under elevated 13CO2 conditions. In a crossover design, two dairy cows received pulse doses of two 13C-enriched grass silages and chromium-mordanted neutral detergent fibre (Cr-NDF) into the rumen. The two 13C-enriched grass silages used differed in digestibility and were grown under identical field conditions as the bulk silages fed to the animals. Faecal excretion patterns of 13C-enriched dry matter (13C-DM), neutral detergent fibre (13C-NDF) and Cr-NDF were established, and a nonlinear multicompartmental model was used to determine their rumen passage kinetics. In addition, the 13C-enriched silages were incubated in rumen liquid in an in vitro batch culture system at different time intervals to determine the effect of fermentation on 13C-enrichment in the residue. The in vitro study showed that the 13C : 12C ratios in DM and NDF residues remained stable from 24 h of incubation onwards. In addition, in vitro fractional degradation rates for 12C in the DM and NDF did not differ from those of 13C, indicating that fermentative degradation does not affect the 13C : 12C ratio in the DM nor in the NDF fraction of the residue. Model fits to the faecal excretion curves showed a significant difference in fractional rumen passage rates between Cr-NDF, 13C-DM and 13C-NDF (P = 0.025). Silage type had no clear effect on rumen passage kinetics (P = 0.081). Moreover, it showed that peak enrichments for 13C-DM and 13C-NDF in faeces were reached at 30.7 and 41.7 h post dosing, respectively. This is well after the time (24 h) when the 13C : 12C ratios of the in vitro unfermented residues have reached stable enrichment level. Fractional rate constants for particle passage from the rumen are estimated from the descending slope of faecal excretion curves. The present study shows that the decline in 13C : 12C ratio after peak enrichment is not affected by fermentative degradation and therefore can be used to assess feed component-specific fractional passage rates.
    The good, the bad and the plenty: interactive effects of food quality and quantity on the growth of different Daphnia species
    Bukovinszky, T. ; Verschoor, A.M. ; Helmsing, N.R. ; Bezemer, T.M. ; Bakker, E.S. ; Vos, M. ; Domis, L.N.D. - \ 2012
    PLoS ONE 7 (2012)9. - ISSN 1932-6203 - 8 p.
    life-history - fresh-water - aquatic herbivores - body size - stoichiometry - zooplankton - limitation - performance - diets - cladocerans
    Effects of food quality and quantity on consumers are neither independent nor interchangeable. Although consumer growth and reproduction show strong variation in relation to both food quality and quantity, the effects of food quality or food quantity have usually been studied in isolation. In two experiments, we studied the growth and reproduction in three filter-feeding freshwater zooplankton species, i.e. Daphnia galeata x hyalina, D. pulicaria and D. magna, on their algal food (Scenedesmus obliquus), varying in carbon to phosphorus (C:P) ratios and quantities (concentrations). In the first experiment, we found a strong positive effect of the phosphorus content of food on growth of Daphnia, both in their early and late juvenile development. Variation in the relationship between the P-content of animals and their growth rate reflected interspecific differences in nutrient requirements. Although growth rates typically decreased as development neared maturation, this did not affect these species-specific couplings between growth rate and Daphnia P-content. In the second experiment, we examined the effects of food quality on Daphnia growth at different levels of food quantity. With the same decrease in P-content of food, species with higher estimated P-content at zero growth showed a larger increase in threshold food concentrations (i.e. food concentration sufficient to meet metabolic requirements but not growth). These results suggest that physiological processes such as maintenance and growth may in combination explain effects of food quality and quantity on consumers. Our study shows that differences in response to variation in food quality and quantity exist between species. As a consequence, species-specific effects of food quality on consumer growth will also determine how species deal with varying food levels, which has implications for resource-consumer interactions
    Beam trawlermen take feet off gas in response to oil price hikes
    Beare, D.J. ; Machiels, M.A.M. - \ 2012
    ICES Journal of Marine Science 69 (2012)6. - ISSN 1054-3139 - p. 1064 - 1068.
    north-sea plaice - fishing effort - fisheries - diets
    Average towing speed by Dutch beam trawlermen has fallen substantially between 2002 and 2009. Changes in towing speed are related to changes in oil price. The price of their valuable main target species (sole, Solea vulgaris) did not influence towing speed.
    Evaluation of local protein resources for growing pigs in Central Vietnam
    Nguyen Thi Hoa Ly, Ly - \ 2012
    Wageningen University. Promotor(en): Martin Verstegen; W.H. Hendriks, co-promotor(en): L.D. Ngoan. - S.l. : s.n. - ISBN 9789461732835 - 145
    diervoeding - varkens - eiwitten - groei - cassave - diëten - zoete aardappelen - vietnam - animal nutrition - pigs - proteins - growth - cassava - diets - sweet potatoes - vietnam

     The general objectives of the work presented here were to evaluate processing methods for the preservations of cassava leaves (CL) and sweet potato vines (SPV) for later feeding during feed shortages in Vietnam. In addition, the nutritional value (including hydrogen cyanide (HCN) contents) of stored and processed CL and SPV as ingredients in diets for pigs were studied to determine their optimal use.

    The impact of different levels of various carbohydrates added to CL on ensiling and chemical properties was investigated (study 1). Inclusion of rice bran or cassava root meal at 5 or 10% (fresh basis),produced good quality silage that can be stored for up to three months. Ensiling reduced the HCN content up to 80% compared to the content in fresh CL. Using ensiled or dry CL and SPV to replace 70%of the crude protein in a practical fish meal based diet commonly used in Vietnam, gave similar performance results and carcass traits of Large White×Mong Caipigs (study 2). However, increasing ensiled CL from variety KM94 from 0 to 20% (in DM) in diets caused a significant decrease in the average daily gain of pigs but resulted in a 9-18% reduction in feed cost (study 3). Studies into the ileal and total tract apparent digestibility of amino acids and crude protein of ensiled and dried CL and SPV showed that these feed ingredients have the potential to improve the supply of amino acids and protein to growing pigs when fed practical diets (study 4). The chemical analyses indicated CL to have a higher crude protein content than SPV and that ensiling slightly decreases the crude protein as well as the amino acids content. Ensiling however, resulted in a higher digestibility of dietary nutrients compared to drying. Thefirst and second limiting amino acids for ensiled and dried CL and SPV for growing pigs were methionine+cysteine and lysine. Mixing ensiled CL and SPV vines may provide additional benefits in terms of amino acid digestibility over feeding these ingredients alone to pigs. Supplementation of diets containing ensiled CL with methionine and lysine showed that the performance of growing pigs can be increased, as well as the economic benefits for farmers (study 5).

    The work presented shows that CL and SPV are economical alternatives for more traditionally protein source (e.g. fish meal, soybean meal) for pigs in Vietnam. Ensiling appears to be a practical solution to conserve sweet potato vines and cassava leaves and provide a solution for the rainy season when preservation by sun-drying is difficult.

     

    Effects of dietary changes on heat stress in broiler and Kampung chickens
    Syafwan, W. - \ 2012
    Wageningen University. Promotor(en): Martin Verstegen; Wouter Hendriks, co-promotor(en): Rene Kwakkel. - S.l. : s.n. - ISBN 9789461731326 - 199
    vleeskuikens - kippen - gevogeltevoeding - diervoeding - diëten - voer - warmtestress - voedingsgedrag - vleeskuikenresultaten - voedingsfysiologie - broilers - fowls - fowl feeding - animal nutrition - diets - feeds - heat stress - feeding behaviour - broiler performance - nutrition physiology

    Poultry meat production has increased drastically over the last 35 years. Most developing countries are in the tropics and often have high ambient temperatures. At high ambient temperatures, chickens exhibit a slower growth rate due to a reduced feed intake. In order to limit the reduction in feed intake, a feeding strategy should be applied which decreases the level of heat production and/or increases the possibilities for heat dissipation. Such a feeding strategy can be based on feed that gives less heat because of lower energy costs of digestion or provides fewer nutrients that lead to a high heat production. This thesis studied how birds subjected to chronic heat stress change feed intake of especially crude protein and total energy. In addition, a wet feeding strategy that might alleviate the adverse effects of heat stress on performance was applied. Chickens exposed to choice feeding responded similarly at normal and at high ambient temperatures. They composed from a choice of a control diet, an energy rich diet and a protein rich diet a diet with a higher energy (HE) content and a lower protein content compared to the standard control diet. At high temperatures, chickens will reduce feed intake because they want to avoid or reduce a high body temperature. When the chickens were fed a wet-HE diet, feed intake and BW gain were higher in broiler chickens compared with feeding a dry-HE diet. The most beneficial effects of a wet diet occurred with a high energy diet. The indigenous Kampung chickens have been acclimatized to a high ambient temperature and did not benefit from a wet diet.

    In the present study, temperature had a major effect on relative lengths and empty weights of gastrointestinal tract segments in broiler chickens on day 42. Relative lengths of most gastrointestinal tract segments were affected by diet formulation at day 21 and 42, but not relative empty weight. Control-fed birds had shorter relative lengths than HE-fed birds, suggesting that the higher BW gain of control-fed birds were not accompanied by a similar increase in length of the gastrointestinal tract. Wetting the diet did not increase empty weights of intestines both at days 21 and 42. In Kampung chickens, effects of diet formulation on gastrointestinal tract development disappeared when the birds grew older, suggesting that this type of bird adapts easily to changes in dietary nutrient content. A positive effect of the relative weight of the intestine of birds fed a wet diet was observed in Kampung chickens. In general, it seems that the Kampung chickens grow proportionally but broiler carcass is growing faster than its gastrointestinal tract in control- and wet-fed birds.

    Key words: Self-selection, temperature, wet diet, broiler, indigenous chicken


    Ileal and total tract apparent crude protein and amino acid digestibility of ensiled and dried cassava leaves and sweet potato vines in growing pigs
    Nguyen, T.H.L. ; Ngoan, L.D. ; Bosch, G. ; Verstegen, M.W.A. ; Hendriks, W.H. - \ 2012
    Animal Feed Science and Technology 172 (2012)3-4. - ISSN 0377-8401 - p. 171 - 179.
    groundnut foliage - leucaena leaves - diets - meal - inclusion - retention - products - roots - fiber - stems
    The present study was conducted to determine the ileal and total tract apparent digestibility of crude protein (CP) and amino acids (AA) in ensiled and dried cassava (Manihot esculenta) leaves (CL) and sweet potato (Ipomoea batatas) vines (SPV) as a single ingredient or in a 50:50 mixture of CL + SPV in growing (>60 kg BW) pigs. Coefficients of ileal (CIAD) and total tract (CTTAD) apparent digestibilities of organic matter (OM), CP, AA, crude fibre (CF) and neutral detergent fibre (aNDFom) were determined in growing pigs fed practical diets. The CP in the diets originated mainly from ensiled and dried CL, SPV or CL + SPV with the main energy source originating from ensiled cassava root which provided less than 9% of the dietary CP. The six diets were formulated to contain 120 g CP/kg DM, 13 MJ ME/kg DM and were fed to 60 kg growing pigs in a 6 × 6 Latin square design. Daily intake of OM, CF, aNDFom and ME differed (P
    A Bayesian approach to analyze energy balance data from lactating dairy cows
    Strathe, A.B. ; Dijkstra, J. ; France, J. ; Lopez, S. ; Yan, T. ; Kebreab, E. - \ 2011
    Journal of Dairy Science 94 (2011)5. - ISSN 0022-0302 - p. 2520 - 2531.
    growing pigs - metaanalysis - maintenance - winbugs - impact - diets
    The objective of the present investigation was to develop a Bayesian framework for updating and integrating covariate information into key parameters of metabolizable energy (ME) systems for dairy cows. The study addressed specifically the effects of genetic improvements and feed quality on key parameters in current ME systems. These are net and metabolizable energy for maintenance (NE(M) and ME(M), respectively), efficiency of utilization of ME for milk production (k(L)) and growth (k(G)), and efficiency of utilization of body stores for milk production (k(T)). Data were collated from 38 studies, yielding 701 individual cow observations on milk energy, ME intake, and tissue gain and loss. A function based on a linear relationship between milk energy and ME intake and correcting for tissue energy loss or gain served as the basis of a full Bayesian hierarchical model. The within-study variability was modeled by a Student t-distribution and the between-study variability in the structural parameters was modeled by a multivariate normal distribution. A meaningful relationship between genetic improvements in milk production and the key parameters could not be established. The parameter k(L) was linearly related to feed metabolizability, and the slope predicted a 0.010 (-0.0004; 0.0210) change per 0.1-unit change in metabolizability. The effect of metabolizability on k(L) was smaller than assumed in present feed evaluation systems and its significance was dependent on collection of studies included in the analysis. Three sets of population estimates (with 95% credible interval in parentheses) were generated, reflecting different degrees of prior belief: (1) Noninformative priors yielded 0.28 (0.23; 0.33) MJ/(kg(0.75)d), 0.55 (0.51; 0.58), 0.86 (0.81; 0.93) and 0.66 (0.58; 0.75), for NE(M), k(L), k(G), and k(T), respectively; (2) Introducing an informative prior that was derived from a fasting metabolism study served to combine the most recent information on energy metabolism in modern dairy cows. The new estimates of NE(M), k(L), k(G) and k(T) were 0.34 (0.28; 0.39) MJ/(kg(0.75)d), 0.58 (0.54; 0.62), 0.89 (0.85; 0.95), and 0.69 (0.60; 0.79), respectively; (3) finally, all informative priors were used that were established from literature, yielding estimates for NE(M), k(L), k(G), and k(T) of 0.29 (0.11; 0.46) MJ/(kg(0.75)d), 0.60 (0.54; 0.70), 0.70 (0.50; 0.88), and 0.80 (0.67; 0.97), respectively. Bayesian methods are especially applicable in meta-analytical studies as information can enter at various stages in the hierarchical model.
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