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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Hygienic behaviour in honeybees: a comparison of two recording methods and estimation of genetic parameters
Facchini, Elena ; Bijma, Piter ; Pagnacco, Giulio ; Rizzi, Rita ; Brascamp, Evert Willem - \ 2019
Apidologie 50 (2019)2. - ISSN 0044-8435 - p. 163 - 172.
freeze-killed brood test - heritability - honeybee - hygienic behaviour - repeatability

Hygienic behaviour (HB) in honeybees reflects social immunity against diseases and parasites. Young bees showing HB detect, uncap, and remove infested brood from a colony. We developed a new variant of freeze-killed brood (FKB*) test to optimise the duration of the HB test, the costs, and safety for the operator. In 2016, we performed a comparison between traditional FKB and FKB* on 25 unselected and unrelated colonies in the apiary of the University of Milano. To estimate repeatability and heritability, in 2017 and 2018, FKB* was used to phenotype, respectively, 56 and 95 colonies twice, in the context of a breeding programme. FKB* took less time and required a smaller amount of liquid nitrogen. The two methods showed a correlation between colony effects of 0.93, indicating that they measure the same trait. For single records, the phenotypic correlation between both methods was 0.64. Estimated heritability and repeatability for single records HB were 0.23 and 0.24, respectively, whilst heritability for the average HB value of two records was 0.37.

'WUR-bijen niet resistent gegen varroa'
Brascamp, Pim ; Blacquiere, Tjeerd - \ 2019
De beoordeling van volken en het nut van teeltwaardeschatting
Brascamp, Pim - \ 2019
Correction to: Heritabilities and genetic correlations for honey yield, gentleness, calmness and swarming behaviour in Austrian honey bees
Brascamp, Evert W. ; Willam, Alfons ; Boigenzahn, Christian ; Bijma, Piter ; Veerkamp, Roel F. - \ 2018
Apidologie 49 (2018)4. - ISSN 0044-8435 - p. 462 - 463.

In the paper, we computed the phenotypic variances of traits ignoring that the worker effect is in fact the colony mean, which has consequences for the estimates of heritabilities.

Wie beslist, de natuur, de imker of beide? : Selectie bij bijen
Blacquière, T. ; Brascamp, P. - \ 2018
Bijenhouden 2018 (2018)1. - ISSN 1877-9786 - p. 14 - 19.
Selecteren is hetzelfde als kiezen. Sinds bijen worden gehouden hebben imkers gekozen welke volken ze aanhouden en welke niet. Er werd altijd al gekozen en daarmee de volgende generatie koninginnen, darrenmoeders en darren bepaald. Elke imker had zijn eigen wisselende voorkeuren voor eigenschappen en ras. Toch had de natuur ook inbreng: zwermen vertrokken en zwermen kwamen.
Duitse plannen om koninginnen te selecteren op grond van hun DNA
Brascamp, Pim - \ 2017
The basic concept of honey bee breeding programs
Uzunov, A. ; Brascamp, Pim ; Büchler, R. - \ 2017
Bee World 94 (2017)3. - ISSN 0005-772X - p. 84 - 87.
Selective honey bee breeding is a phenomenon that fascinates beekeepers around the world. They often regard it as one of the most enigmatic and complex aspects of beekeeping. Indeed, according to our experiences participating in many international projects, both beekeepers and bee experts without a background in plant or animal breeding often have trouble correctly interpreting and conceptually visualizing the breeding process. These difficulties arise partly because of the complex reproductive biology of honey bees, where queens mate with a multitude of drones. Fundamentally the greatest struggle for people to understand is how selection of animals with preferred characteristics in one generation leads to improved progeny in the next.
Economic evaluation of progeny-testing and genomic selection schemes for small-sized nucleus dairy cattle breeding programs in developing countries
Kariuki, Charles ; Brascamp, Pim ; Komen, H. ; Kahi, A.K. ; Arendonk, Johan van - \ 2017
Journal of Dairy Science 100 (2017)3. - ISSN 0022-0302 - p. 2258 - 2268.
In developing countries minimal and erratic performance and pedigree recording impede implementation of large-sized breeding programs. Small-sized nucleus programs offer an alternative but rely on their economic performance for their viability. We investigated the economic performance of 2 alternative small-sized dairy nucleus programs [i.e., progeny testing (PT) and genomic selection (GS)] over a 20-yr investment period. The nucleus was made up of 453 male and 360 female animals distributed in 8 non-overlapping age classes. Each year 10 active sires and 100 elite dams were selected. Populations of commercial recorded cows (CRC) of sizes 12,592 and 25,184 were used to produce test daughters in PT or to create a reference population in GS, respectively. Economic performance was defined as gross margins, calculated as discounted revenues minus discounted costs following a single generation of selection. Revenues were calculated as cumulative discounted expressions (CDE, kg) × 0.32 (€/kg of milk) × 100,000 (size commercial population). Genetic superiorities, deterministically simulated using pseudo-BLUP index and CDE, were determined using gene flow. Costs were for one generation of selection. Results show that GS schemes had higher cumulated genetic gain in the commercial cow population and higher gross margins compared with PT schemes. Gross margins were between 3.2- and 5.2-fold higher for GS, depending on size of the CRC population. The increase in gross margin was mostly due to a decreased generation interval and lower running costs in GS schemes. In PT schemes many bulls are culled before selection. We therefore also compared 2 schemes in which semen was stored instead of keeping live bulls. As expected, semen storage resulted in an increase in gross margins in PT schemes, but gross margins remained lower than those of GS schemes. We conclude that implementation of small-sized GS breeding schemes can be economically viable for developing countries.
Heritabilities and genetic correlations for honey yield, gentleness, calmness and swarming behaviour in Austrian honey bees
Brascamp, Evert ; Willam, Alfons ; Boigenzahn, Christian ; Bijma, Piter ; Veerkamp, Roel F. - \ 2016
Apidologie 47 (2016)6. - ISSN 0044-8435 - p. 739 - 748.
estimated breeding value - genetic correlation - genetic parameter - heritability - honey bee

Heritabilities and genetic correlations were estimated for honey yield and behavioural traits in Austrian honey bees using data on nearly 15,000 colonies of the bee breeders association Biene Österreich collected between 1995 and 2014. The statistical models used distinguished between the genetic effect of workers and that of the queen of the colony. Heritability estimates for worker effect were larger than those for queen effect. Genetic correlations between both effects were negative. Heritability estimates for the sum of both effects (i.e. selection criterion) were 0.27, 0.37, 0.38 and 0.06 for honey yield, gentleness, calmness and swarming behaviour, respectively, indicating that meaningful genetic improvement is possible. Genetic correlations between these traits were generally small to medium, with large standard errors, with the exception of the high genetic correlation between gentleness and calmness. The models we present here can be used to estimate breeding values in honey bees.

Estimation of Genetic Parameters and Breeding Values in Honey Bees
Brascamp, E.W. ; Veerkamp, R.F. ; Bijma, P. - \ 2014
Methods to estimate breeding values in honey bees
Brascamp, E.W. ; Bijma, P. - \ 2014
Genetics, Selection, Evolution 46 (2014). - ISSN 0999-193X
computing inbreeding coefficients - numerator relationship matrix - large populations - animal-model - apis - prediction - selection - inverse
Background Efficient methodologies based on animal models are widely used to estimate breeding values in farm animals. These methods are not applicable in honey bees because of their mode of reproduction. Observations are recorded on colonies, which consist of a single queen and thousands of workers that descended from the queen mated to 10 to 20 drones. Drones are haploid and sperms are copies of a drone’s genotype. As a consequence, Mendelian sampling terms of full-sibs are correlated, such that the covariance matrix of Mendelian sampling terms is not diagonal. Results In this paper, we show how the numerator relationship matrix and its inverse can be obtained for honey bee populations. We present algorithms to derive the covariance matrix of Mendelian sampling terms that accounts for correlated terms. The resulting matrix is a block-diagonal matrix, with a small block for each full-sib family, and is easy to invert numerically. The method allows incorporating the within-colony distribution of progeny from drone-producing queens and drones, such that estimates of breeding values weigh information from relatives appropriately. Simulation shows that the resulting estimated breeding values are unbiased predictors of true breeding values. Benefits for response to selection, compared to an existing approximate method, appear to be limited (~5%). Benefits may however be greater when estimating genetic parameters. Conclusions This work shows how the relationship matrix and its inverse can be developed for honey bee populations, and used to estimate breeding values and variance components.
Estimation of genetic parameters and breeding values in honey bees
Brascamp, E.W. ; Veerkamp, R.F. ; Bijma, P. - \ 2014
Erfelijke verbetering van bijen : "Kunt u mij de weg naar Hamelen vertellen, meneer?"
Brascamp, E.W. - \ 2013
Bijenhouden 7 (2013)6. - ISSN 1877-9786 - p. 25 - 26.
honingbijen - rassen (dieren) - dierveredeling - professionele bijenhouderij - genetische bronnen van diersoorten - imkers - diergezondheid - kennis - resistentie van variëteiten - honey bees - breeds - animal breeding - commercial beekeeping - animal genetic resources - beekeepers - animal health - knowledge - varietal resistance
Er is toenemende belangstelling voor de erfelijke verbetering van de bijenpopulatie. Dat komt grotendeels doordat telkens weer tijdig varroa bestrijden tegen gaat staan en erfelijke varroaresistentie dus heel wat waard is. In dit artikel worden ervaringsfeiten met betrekking tot veredeling van landbouwhuisdieren vertaald in zeven vuistregels die voor alle selectie gelden, inclusief die bij de honingbij.
Bijen: fascinerend, essentieel en bedreigd
Brascamp, T. ; Blacquière, T. ; Steen, J.J.M. van der - \ 2011
Bijenhouden 2011 (2011). - ISSN 1877-9786 - p. 5 - 5.
Het ‘College Beekeeper’ Initiatief
Smith, M. ; Brascamp, T. - \ 2011
Professional Development at the University; a career counseling course
Gulikers, J.T.M. ; Mulder, M. ; Brascamp, E.W. - \ 2010
Selective breeding in organic dairy production
Nauta, W.J. - \ 2009
Wageningen University. Promotor(en): Pim Brascamp; Jandouwe van der Ploeg, co-promotor(en): Henk Bovenhuis; Dirk Roep. - [S.l. : S.n. - ISBN 9789085853602 - 160
melkkoeien - dierveredeling - fokkerijmethoden - biologische landbouw - melkproductiekenmerken - genotype-milieu interactie - melkveehouderij - dairy cows - animal breeding - animal breeding methods - organic farming - milk production characteristics - genotype environment interaction - dairy farming
Organic dairy farming started to take off in the early 1990s, when the European Union laid down organic standards for animal production. Until now, however, only incidental steps have been taken towards organic breeding and organic farmers mainly use breeding stock from conventional breeding programmes. This thesis focuses on the possibilities for breeding in organic dairy farming. This thesis starts with describing the basic backgrounds of organic dairy farming and the results of a study that was carried out in 1999-2000 on the vision on cattle breeding. The main conclusions are that breeding in organic dairy farming should be in line with the intensions of organic farming and that farmers need animals that fit to their extensive farming system. This study is followed by describing the differences and the magnitude of genotype by environment interaction (G x E) between conventional and organic dairy production. There proved to be significant differences in levels of milk production, percentage of protein in the milk, milk cell count and fertility between Holstein heifers on organic or conventional farms. A fairly large impact of G x E was found indicating that organic dairy farmers might have difficulty with selecting the right animals from the conventional supply of breeding bulls. This effect may be caused by the lower uptake of energy by cows in organic agriculture. After this a study into organic dairy farmers’ breeding aims in relation to their farm management was carried out in 2005. This study shows that, despite differences in farm management, organic farmers had more or less the same breeding aim and many farmers were already experimenting with breeds and crosses in a quest for the most suitable type of cow for their farm. There was, however, no relationship between the farm management system and the breed or cross used, which indicates that although farmers demand suitable animals, they do not know what type of cow this would be. Based on the results of the different studies, three distinct options are formulated for breeding in organic dairy farming: (1) use of adapted conventional breeding, (2) a separate breeding programme and (3) a breeding system based on natural mating. The advantages and disadvantages of each of the three breeding options are described in relation to naturalness, technical breeding issues, societal concerns and costs and benefits. These illustrate the complexity of the breeding issue in both breeding-technology and social terms. Restricting the use of conventional breeding would effectively mean the rejection of a system with a long and successful history, and throw organic dairy breeding back on its own resources. It is concluded that ‘system innovations’ at multiple levels are needed to create new, sustainable breeding systems, stakeholders must join forces to stimulate the development towards appropriate breeding
Genotype by Environment Interaction for Milk Production Traits Betweeen Organic and Conventional Dairy Production in The Netherlands
Nauta, W.J. ; Veerkamp, R.F. ; Brascamp, E.W. ; Bovenhuis, H. - \ 2006
Journal of Dairy Science 89 (2006)7. - ISSN 0022-0302 - p. 2729 - 2737.
biologische landbouw - conversie - melkveehouderij - celgetal - melkproductie - genetische parameters - heritability - dierveredeling - organic farming - conversion - dairy farming - somatic cell count - milk production - genetic parameters - animal breeding - somatic-cell score - genetic-parameters - holstein cows - phenotypic relationships - protein yield - records - models - fat
Estimates of genetic parameters for organic dairy farming have not been published previously, and neither is information available on the magnitude of genotype by environment interaction (GxE) between organic and conventional farming. However, organic farming is growing worldwide and basic information about genetic parameters is needed for future breeding strategies for organic dairy farming. The goal of this study was to estimate heritabilities of milk production traits under organic farming conditions and to estimate the magnitude of GxE between organic and conventional dairy farming. For this purpose, production records of first-parity Holstein heifers were used. Heritabilities of milk, fat and protein yield, and somatic cell score (SCS) were higher under organic farming conditions. For percentages of fat and protein, heritabilities of organic and conventional production were very similar. Genetic correlations between preorganic and organic, and organic and conventional milk production were 0.79 and 0.80, respectively. For fat yield, these correlations were 0.86 and 0.88, and for protein yield, these were 0.78 and 0.71, respectively. Our findings indicate that moderate GxE was present for yield traits. For percentage of fat and protein and SCS, genetic correlations between organic and conventional and preorganic production were close to unity, indicating that there was no GxE for these traits.
Somatic cell count patterns. Improvement of udder health by genetics and management
Haas, Y. de - \ 2003
Wageningen University. Promotor(en): Pim Brascamp, co-promotor(en): Roel Veerkamp; H.W. Barkema. - Rotterdam : Optima Grafische communicatie - ISBN 9058088731 - 175
melkkoeien - celgetal - rundermastitis - bacterieziekten - lactatie - genetische factoren - diergezondheid - genetische verbetering - agrarische bedrijfsvoering - zuivelwetenschap - somatische celgenetica - dairy cows - somatic cell count - bovine mastitis - bacterial diseases - lactation - genetic factors - animal health - genetic improvement - farm management - dairy science - somatic cell genetics
Genetic analysis of feather pecking behavior in laying hens
Buitenhuis, A.J. - \ 2003
Wageningen University. Promotor(en): Pim Brascamp, co-promotor(en): Jan van der Poel. - [S.l.] : S.n. - ISBN 905808874X - 153
hennen - pluimvee - verenpikken - diergedrag - genetische analyse - genetische factoren - lijnverschillen - stressreactie - kwantitatieve kenmerken - heritability - genetica - hens - poultry - feather pecking - animal behaviour - genetic analysis - genetic factors - line differences - stress response - quantitative traits - heritability - genetics
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