Staff Publications

Staff Publications

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    '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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Farm-level risk factors for bovine mastitis in Dutch automatic milking dairy herds
Deng, Z. ; Koop, G. ; Lam, T.J.G.M. ; Lans, I.A. van der; Vernooij, J.C.M. ; Hogeveen, H. - \ 2019
Journal of Dairy Science 102 (2019)5. - ISSN 0022-0302 - p. 4522 - 4535.
automatic milking system - mastitis - nonlinear principal component analysis - principal component regression - risk factor

Automatic milking systems (AMS) are installed on a growing number of dairy farms worldwide. Management to support good udder health might be different on farms with an AMS compared with farms milking with a conventional milking system, as risk factors for mastitis on farms using an AMS may differ. The aim of this study was to identify farm level factors associated with mastitis on Dutch dairy farms using an AMS. In 2008, risk factor data were collected using a questionnaire combined with on-farm recordings of cow, stall, and AMS hygiene on 135 farms. These risk factor data were linked to 4 udder-health-associated dependent variables: average herd somatic cell count (HeSCCav), variance of the average herd somatic cell count (SCC) on test days (HeSCCvar), the average proportion of new high SCC cases (NHiSCC), and the farmer-reported annual incidence rate of clinical mastitis (IRCM). We employed regression models using multiple imputation to deal with missing values. Due to the high dimensionality of the risk factor data, we also performed nonlinear principal component analysis (NLPCA) and regressed the dependent variables on the principal components (PC). Good hygiene of cows and of AMS were found to be related to a lower HeSCCav and less NHiSCC. Effective postmilking teat disinfection was associated with a lower NHiSCC. A higher bulk tank milk SCC threshold for farmers' action was related to more NHiSCC. Larger farm size was related to lower HeSCCvar but higher NHiSCC. Negative attitude of farmers to animal health, higher frequency of checking AMS, and more time spent on viewing computer data were all positively related to higher IRCM. An NLPCA with 3 PC explained 16.3% of the variance in the risk factor variables. Only the first 2 PC were associated with mastitis. The first PC reflected older and larger farms with poor cow hygiene and AMS hygiene, and was related to higher HeSCCav and NHiSCC, whereas the second PC reflected newly built smaller farms with poor cow hygiene and low milk production, and was associated with higher HeSCCvar and NHiSCC, but lower IRCM. Our study suggests that many of the risk factors on conventional milking system farms are applicable to AMS farms, specifically concerning hygiene of the cows and the milking machine, but on large AMS farms, udder health may need more attention than on smaller AMS farms. Multiple imputation is instrumental to deal with missing values and NLPCA is a useful technique to process high dimensional data in our study.

Invited review: abomasal damage in veal calves
Bus, J.D. ; Stockhofe, N. ; Webb, L.E. - \ 2019
Journal of Dairy Science 102 (2019)2. - ISSN 0022-0302 - p. 943 - 960.
abomasal damage - etiology - risk factor - veal calf

Within all cattle production systems, veal calves are the most severely affected by abomasal damage, with current prevalence at slaughter ranging from 70 to 93% of all animals affected. Although most damage is found in the pyloric region of the abomasum, fundic lesions are also found. Despite past research into the etiology of abomasal damage and the many risk factors that have been proposed, consensus on the causal factors of abomasal damage in veal calves has not yet been reached. The aim of this review was to integrate and analyze available information on the etiology of, and possible risk factors for, abomasal damage in veal calves. We describe various proposed pathways through which risk factors may contribute to damage formation and conclude that the etiology of abomasal damage is most likely multifactorial, with diet being a main contributor. Pyloric lesions, the most common type of damage in veal calves, are likely the result of large and infrequent milk and solid feed meals, whereas fundic lesions may be caused by stress, although the evidence for this is inconclusive. Providing calves with multiple smaller milk and solid feed meals (or ad libitum provision) may decrease abomasal damage. In future research, ulcers, erosions, and scars as well as fundic and pyloric lesions should be recorded separately, because etiologies of these may differ. Further research is required to understand the exact pathway(s) by which milk replacer causes abomasal damage in veal calves; that is, whether low abomasal pH, overloading, or composition are important. Further research is also required to elucidate whether rapid intake of milk replacer and solid feed, which is influenced by restricted amounts fed, inter-calf competition, and calf breed, increases abomasal damage. Research is also needed into the effect of medication and nutrient deficiencies other than iron. The types of experimental designs that can be used for future research could be enhanced if a means to assess abomasal damage antemortem is developed. We conclude that it is unlikely that abomasal or ruminal hairballs, iron deficiency, water provision, and various infections and diseases are significant contributors to abomasal damage in veal calves.

Bioactive compounds: Definition and assessment of activity
Biesalski, H.K. ; Dragsted, L.O. ; Elmadfa, I. ; Grossklaus, R. ; Müller, M.R. ; Schrenk, D. ; Walter, P. ; Weber, P. - \ 2009
Nutrition 25 (2009)11-12. - ISSN 0899-9007 - p. 1202 - 1205.
risk factor - disease
Biomarkers and their role in evaluating efficacy and safety were the topic of the 23rd Hohenheim Consensus Meeting at the University of Hohenheim in Stuttgart. Scientists who had published and reviewed scientific and regulatory papers on the topic were invited, among them basic researchers, toxicologists, clinicians, and nutritionists. The participants were presented with 11 questions (in bold font), which were discussed and answered (in italic font) at the workshop, with the aim of summarizing the current state of knowledge on the subject. The explicatory text accompanying the short answers was produced and agreed on after the conference and was backed up by corresponding references
Bioavailability of Food Folates is 80% of that of folic acid 1-3
Winkels, R.M. ; Brouwer, I.A. ; Siebelink, E. ; Katan, M.B. ; Verhoef, P. - \ 2007
American Journal of Clinical Nutrition 85 (2007)2. - ISSN 0002-9165 - p. 465 - 473.
plasma homocysteine concentrations - human serum - risk factor - disease - prevention - vegetables - humans - trial - assay
Background: The bioavailability of natural food folates is lower than that of synthetic folic acid, but no agreement exists as to the extent of the difference. Objective: In a 4-wk dietary intervention study, we determined the aggregate bioavailability of food folates from fruit, vegetables, and liver relative to that of folic acid. Design: Seventy-two healthy adults were randomly divided into 4 treatment groups. Group A (n = 29) received a high-folate diet with 369 µg food folate/d and a placebo capsule; groups B, C, and D (n = 14 or 15) received a low-folate diet with 73 µg food folate/d and folic acid capsules. These capsules contained 92 µg folic acid/d for group B, 191 µg for group C, and 289 µg for group D. In addition, all 72 subjects daily ingested a capsule with 58 µg [13C11]-labeled folic acid. We measured the percentage of [13C11]-labeled folate in plasma folate at the end of the intervention and ascertained the changes in serum folate concentrations over the 4 wk of the intervention. Results: Bioavailability of food folate relative to that of folic acid was 78% (95% CI: 48%, 108%) according to [13C11]-labeled folate and 85% (52%, 118%) according to changes in serum folate concentrations. Conclusions: The aggregate bioavailability of folates from fruit, vegetables, and liver is 80% of that of folic acid. The consumption of a diet rich in food folate can improve the folate status of a population more efficiently than is generally assumed.
Folate and the methylenetetrahydrofolate reductase 677C ---> T mutation correlate with cognitive performance
Durga, J. ; Boxtel, M.P.J. van; Schouten, E.G. ; Bots, M.L. ; Kok, F.J. ; Verhoef, P. - \ 2006
Neurobiology of aging 27 (2006)2. - ISSN 0197-4580 - p. 334 - 343.
ischemic-heart-disease - alzheimers-disease - risk factor - folic-acid - 10-formyltetrahydrofolate dehydrogenase - mendelian randomization - plasma homocysteine - oxidative stress - elderly patients - common mutation
Low folate status has been associated with cognitive decline. We investigated the association of folate status and the 5,10-methylenetetrahydrofolate reductase (MTHFR) 677C ¿ T polymorphism with performance on a battery of neuropsychological tests. Furthermore, we investigated whether the association of folate with cognitive performance was mediated by plasma homocysteine or risk of vascular disease. We used cross-sectional data from 818 individuals aged 50¿70 years old. Low concentrations of erythrocyte folate but not serum folate were associated with poor performance on complex speed and memory tasks, independent of educational level and conventional risk factors of vascular disease. These associations were not mediated by homocysteine concentrations or carotid intima-media thickness. Subjects with the MTHFR 677TT genotype tended to perform better on cognitive tasks than CC/CT subjects, although this was significant for sensorimotor speed only (differences in Z-scores between MTHFR 677TT homozygotes and CC homozygotes ¿0.15, 95% CI: ¿0.30 to 0.00). Low concentrations of erythrocyte folate are associated with decreased cognitive performance, possibly through a homocysteine-independent mechanism such as DNA infidelity and mitochondrial decay.
Morphogenetic movements during cranial neural tube closure in the chick embryo and the effect of homocysteine
Brouns, M.R. ; Afman, L.A. ; VanHauten, B.A.M. ; Hekking, J.W.M. ; Kohler, E.S. ; Straaten, H.W.M. van - \ 2005
Anatomy and Embryology 210 (2005)2. - ISSN 0340-2061 - p. 81 - 90.
rat embryos - convergent extension - spinal neurulation - initial closure - mouse embryos - risk factor - cell-shape - defects - plate - mechanisms
In order to unravel morphogenetic mechanisms involved in neural tube closure, critical cell movements that are fundamental to remodelling of the cranial neural tube in the chick embryo were studied in vitro by quantitative time-lapse video microscopy. Two main directions of movements were observed. The earliest was directed medially; these cells invaginated into a median groove and were the main contributors to the initial neural tube closure. Once the median groove was completed, cells changed direction and moved anteriorly to contribute to the anterior neural plate and head fold. This plate developed into the anterior neuropore, which started to close from the 4-somite stage onwards by convergence of its neural folds. Posteriorly, from the initial closure site onwards, the posterior neuropore started to close almost instantaneously by convergence of its neural folds. Homocysteine is adversely involved in human neural tube closure defects. After application of a single dose of homocysteine to chick embryos, a closure delay at the initial closure site and at the neuropores, flattening of the head fold and neural tube, and a halt of cell movements was seen. A possible interference of Hcy with actin microfilaments is discussed.
Bioavailability of folic acid from fortified pasteurised and UHT-treated milk in humans
Jong, R.J. ; Verwei, M. ; West, C.E. ; Vliet, T. van; Siebelink, E. ; Berg, H. van den; Castenmiller, J.J.M. - \ 2005
European Journal of Clinical Nutrition 59 (2005)8. - ISSN 0954-3007 - p. 906 - 913.
folate-binding-protein - plasma homocysteine concentrations - neural-tube defects - methylenetetrahydrofolate reductase - food fortification - vascular-disease - common mutation - dietary-folate - risk factor - cows milk
Objective The aim of this study was to investigate whether milk fortified with folic acid enhances the folate status of humans and whether the presence of folate-binding proteins (FBP) in pasteurised milk affects the bioavailability of folic acid from fortified milk. In untreated and pasteurised milk, folate occurs bound to FBP, while FBP is (partly) denatured in ultra-high-temperature (UHT)-treated milk. The effect of FBP on folate bioavailability is still unclear. Design, subjects and setting Healthy, free-living subjects (n=69) aged 18-49 y participated in a 4-week double-blind, placebo-controlled dietary intervention study. Intervention In addition to a fully controlled diet, the subjects consumed each day 500 ml of pasteurised or UHT milk, either fortified or not with 200 g folic acid. Results Consumption of fortified milk increased folate concentrations in serum and in red blood cells (RBC) by 6.6-7.0 nmol/l (P
Effects of Betaine Intake on Plasma Homocysteine Concentrations and Consequences for Health
Olthof, M.R. ; Verhoef, P. - \ 2005
Current Drug Metabolism 6 (2005)1. - ISSN 1389-2002 - p. 15 - 22.
coronary-heart-disease - folic-acid - vascular-disease - hemodialysis-patients - n-methyltransferase - synthase deficiency - folate-deficiency - randomized-trials - risk factor - choline
High plasma concentrations of homocysteine may increase risk of cardiovascular disease. Folic acid lowers plasma homocysteine by 25% maximally, because 5-methyltetrahydrofolate is a methyl donor in the remethylation of homocysteine to methionine. Betaine (trimethylglycine) is also a methyl donor in homocysteine remethylation, but effects on homocysteine have been less thoroughly investigated. Betaine in high doses (6 g/d and higher) is used as homocysteine-lowering therapy for people with hyperhomocysteinemia due to inborn errors in the homocysteine metabolism. Betaine intake from foods is estimated at 0.5-2 g/d. Betaine can also be synthesized endogenously from its precursor choline. Studies in healthy volunteers with plasma homocysteine concentrations in the normal range show that betaine supplementation lowers plasma fasting homocysteine dose-dependently to up to 20% for a dose of 6 g/d of betaine. Moreover, betaine acutely reduces the increase in homocysteine after methionine loading by up to 50%, whereas folic acid has no effect. Betaine doses in the range of dietary intake also lower homocysteine. This implies that betaine can be an important food component that attenuates homocysteine rises after meals. If homocysteine plays a causal role in the development of cardiovascular disease, a diet rich in betaine or choline might benefit cardiovascular health through its homocysteine-lowering effects. However betaine and choline may adversely affect serum lipid concentrations, which can of course increase risk of cardiovascular disease. However, whether the potential beneficial health effects of betaine and choline outweigh the possible adverse effects on serum lipids is as yet unclear
Bioavailability of polyglutamyl folic acid relative to that of monoglutamyl folic acid in subjects with different genotypes of the glutamate carboxypeptidase II gene
Boonstra, A. ; Lievers, K.J.A. ; Blom, H.J. ; Verhoef, P. - \ 2004
American Journal of Clinical Nutrition 80 (2004)3. - ISSN 0002-9165 - p. 700 - 704.
neural-tube defects - total homocysteine levels - plasma homocysteine - heart-disease - risk factor - folate - polymorphism - serum - vitamin - hyperhomocysteinemia
Background: Before dietary folate is absorbed, polyglutamate folates are deconjugated to monoglutamates by folylpoly-gamma-glutamyl carboxypeptidase in the small intestine. The 1561T allele of the glutamate carboxypeptidase II gene (GCPII), which codes for folylpoly-gamma-glutamyl carboxypeptidase, may impair intestinal absorption of dietary folates. Objective: Our aim was to study the bioavailability of polyglutamyl folic acid relative to that of monoglutamyl folic acid across GCPII 1561 genotypes. Design: In a randomized study, 180 healthy adults aged 50-75 y received 323 nmol monoglutamyl folic acid/d (n = 59), 262 nmol heptaglutamyl folic acid/d (n = 61), or placebo (n = 60) for 12 wk. Genotypes were assessed after the intervention. The bioavailability of heptaglutamyl folic acid relative to that of monoglutamyl folic acid was calculated by using the changes in serum folate concentration in the treatment groups, after correction for changes in the placebo group and for the administered dose. Results: No subjects with the TT genotype were encountered. At baseline, serum and erythrocyte folate concentrations were higher (P <0.05) in subjects with the CT genotype [16.3 nmol/L (geometric (x) over bar; 95% CI: 13.7,19.3 nmol/L) and 863 nmol/L (735,1012 nmol/L), respectively; n = 19] than in subjects with the CC genotype [ 13.7 (13.1, 14.3) and 685 (652, 721) nmol/L, respectively; n = 161]. Baseline homocysteine concentrations were not significantly different between genotypes. The bioavailability of heptaglutamyl folic acid relative to that of monoglutamyl folic acid was not significantly different between subjects with the CC (64%; 52%, 76%) and CT genotypes (70%; 49%, 91%). Conclusions: The 1561 T allele of the GCPII gene does not impair the bioavailability of polyglutamyl folic acid. However, the allele is associated with higher folate status. This association may be explained by yet unidentified factors controlling the expression of the GCPII gene.
Cystathionine beta-synthase polymorphisms and hyperhomocysteinaemia: an association study
Lievers, K.J.A. ; Kluijtmans, L.A.J. ; Heil, S.G. ; Boers, G.H. ; Verhoef, P. ; Heijer, M. Den; Trijbels, F.J. ; Blom, H.J. - \ 2003
European Journal of Human Genetics 11 (2003). - ISSN 1018-4813 - p. 23 - 29.
coronary-artery disease - risk factor - total homocysteine - vascular-disease - mild hyperhomocysteinemia - plasma homocysteine - heart-disease - cbs gene - cardiovascular-disease - linkage disequilibrium
Hyperhomocysteinaemia is generally accepted as an independent and graded risk factor for both arterial occlusive disease and venous thrombosis. The only way of homocysteine degradation is conversion to cysteine in the transsulfuration pathway in which the regulating step is catalysed by cystathionine beta-synthase (CBS). Mild impairment of CBS function could therefore affect homocysteine concentration, in particular after methionine loading, and consequently cardiovascular disease (CVD) risk. We analysed two silent polymorphisms and one short tandem repeat in the CBS gene (ie 699C-->T, 1080C-->T and -5697 (GT) STR) as genetic markers potentially in linkage disequilibrium with a functional polymorphism. We assessed their association with fasting and post-methionine load homocysteine in 190 patients with arterial occlusive disease, and in 381 controls. No differences in CBS genotype frequencies between cases and controls were found, nor was a particular CBS genotype associated with an elevated risk of arterial occlusive disease. Although we did find a high rate of linkage disequilibrium between the two single nucleotide polymorphisms and the GT STR, none of the genotypes defined by the three CBS variants studied showed an association with elevated fasting, post-load or increase upon methionine loading homocysteine concentrations. In conclusion, we did not find any indication that genetic variation in the CBS gene is associated with increased homocysteine concentrations.
Dietary quality, lifestyle factors and healthy ageing in Europe: the SENECA study
Haveman-Nies, A. ; Groot, C.P.G.M. de; Staveren, W.A. van - \ 2003
Age and Ageing 32 (2003). - ISSN 0002-0729 - p. 427 - 434.
self-rated health - coronary heart-disease - 20 year mortality - physical-activity - elderly people - alcohol-consumption - smoking cessation - older europeans - risk factor - men
Objective: to identify dietary and lifestyle factors that contribute to healthy ageing. Subjects: for the analyses, data of the longitudinal SENECA study were used. The study population consisted of 1091 men and 1109 women aged 70-75 years from Belgium, France, Denmark, Italy, The Netherlands, Portugal, Spain, Switzerland, and Poland. Methods: this European study started with baseline measurements in 1988-1989 and lasted until 30 April 1999. The study includes data on diet, lifestyle and health. The study population is followed for 10 years, and measurements were performed in 1988/1989 (baseline), 1993, and 1999. The relationships of the three lifestyle factors diet, physical activity, and smoking habits to survival and maintenance of health at old age were investigated. Finally it is discussed whether the relationships of healthy lifestyle habits to survival and health contribute to healthy ageing. Results: the unhealthy lifestyle habits smoking, having a low-quality diet, and being physically inactive were singly related to an increased mortality risk (hazard ratios ranged from 1.2 to 2.1). In addition, inactive and smoking persons had an increased risk for a decline in health status as compared with active and non-smoking people. The net effect of a healthy lifestyle on the process of healthy ageing is likely to go together with a compressed cumulative morbidity. Conclusions: a healthy lifestyle at older ages is positively related to a reduced mortality risk and to a delay in the deterioration in health status. This postponement of the onset of major morbidity is likely to go together with a compressed cumulative morbidity. Therefore, health promotion at older ages can contribute to healthy ageing.
Betaine supplementation lowers plasma homocysteine levels in healthy men and women
Steenge, G.R.S. ; Verhoef, P. ; Katan, M.B. - \ 2003
The Journal of Nutrition 133 (2003). - ISSN 0022-3166 - p. 1291 - 1295.
dose folic-acid - cardiovascular-disease - methylenetetrahydrofolate reductase - vascular-disease - risk factor - dietary betaine - methionine - methyltransferase - metabolism - pyridoxine
Elevated levels of plasma total homocysteine are associated with a higher risk of cardiovascular disease. Betaine and 5-methyltetrahydrofolate can remethylate homocysteine into methionine via independent reactions. We determined the effect of daily betaine supplementation, compared with both folic acid and placebo, on plasma concentrations of total homocysteine after an overnight fast and after methionine loading in men and women with mildly elevated homocysteine. Groups of twelve subjects ingested 6 g betaine, 800 jig folic acid with 6 g placebo or 6 g placebo each day for 6 wk. A methionine-loading test (i.e., ingestion Of 100 mg L-methionine/kg body mass) was performed before and after 6 wk of supplementation. Fasting plasma homocysteine decreased by 1.8 mumol/L (95% confidence interval [CI]: -3.6, 0.0, P <0.05) in the betaine group and by 2.7 mumol/L (95% CI: -4.5, -0.9, P <0.05) in the folic acid group. These changes are relative to the change in the placebo group, in which fasting plasma homocysteine rose by 0.5 mumol/L. Furthermore, betaine suppressed the total area under the plasma homocysteine-time curve after methionine loading by 221 mumol - 24 h/L (95% CI: -425, -16, P <0.05) compared with placebo, whereas folic acid had no effect. In conclusion, betaine appears to be highly effective in preventing a rise in plasma homocysteine concentration after methionine intake in subjects with mildly elevated homocysteine. It is not known whether this potential of betaine to "stabilize" circulating homocysteine concentrations lowers the risk of cardiovascular disease. J. Nutr. 133: 1291-1295, 2003.
Polymorphisms in the transcobalamin gene: Association with plasma homocysteine in healthy individuals and vascular disease patients
Lievers, K.J.A. ; Afman, L.A. ; Kluijtmans, L.A.J. ; Boers, G.H.J. ; Verhoef, P. ; Heijer, M. den; Trijbels, F.J.M. ; Blom, H.J. - \ 2002
Clinical Chemistry 48 (2002)9. - ISSN 0009-9147 - p. 1383 - 1389.
risk factor
Background: Hyperhomocysteinemia is an independent risk factor for cardiovascular disease (CVD). Intracellular vitamin B12 deficiency may lead to increased plasma total homocysteine (tHcy) concentrations and because transcobalamin (TC) is the plasma transporter that delivers vitamin B12 to cells, genetic variation in the TC gene may affect intracellular vitamin B12 availability and, consequently, tHcy concentrations. Methods: We examined five sequence variants, i.e., I23V, G94S, P259R, S348F, and R399Q, in the TC gene as possible determinants of tHcy and, concordantly, as possible risk factors for CVD in 190 vascular disease patients and 601 controls. We also studied potential effect-modification of vitamin B12 by genotype. Results: In individuals with high vitamin B12, 259PP individuals had lower tHcy concentrations than 259PR and 259RR individuals. Homozygous 23VV individuals had lower fasting tHcy concentrations than their 23IV and 23II peers. None of the genotypes defined by the three other sequence variants showed an association with tHcy concentrations, nor was any TC genotype associated with an increased CVD risk. Conclusions: In individuals in the highest quartile of the vitamin B12 distribution (>299 pmol/L), tHcy concentrations are lower in 259PP homozygotes than in 259PR and 259RR individuals. Therefore, 259PP individuals, who represent >25% of the general population, may be more susceptible to reduction of plasma tHcy concentrations by increasing the vitamin B12 status
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