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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Exploiting whole genome sequence variants in cattle breeding : Unraveling the distribution of genetic variants and role of rare variants in genomic evaluation
Zhang, Qianqian - \ 2017
University. Promotor(en): Henk Bovenhuis, co-promotor(en): G. Sahana; Mario Calus. - Wageningen : Wageningen University - ISBN 9788793643147 - 249
cattle - genomes - genetic variation - inbreeding - homozygosity - longevity - quantitative traits - animal breeding - animal genetics - rundvee - genomen - genetische variatie - inteelt - homozygotie - gebruiksduur - kwantitatieve kenmerken - dierveredeling - diergenetica

The availability of whole genome sequence data enables to better explore the genetic mechanisms underlying different quantitative traits that are targeted in animal breeding. This thesis presents different strategies and perspectives on utilization of whole genome sequence variants in cattle breeding. Using whole genome sequence variants, I show the genetic variation, recent and ancient inbreeding, and genome-wide pattern of introgression across the demographic and breeding history in different cattle populations. Using the latest genomic tools, I demonstrate that recent inbreeding can accurately be estimated by runs of homozygosity (ROH). This can further be utilized in breeding programs to control inbreeding in breeding programs. In chapter 2 and 4, by in-depth genomic analysis on whole genome sequence data, I demonstrate that the distribution of functional genetic variants in ROH regions and introgressed haplotypes was shaped by recent selective breeding in cattle populations. The contribution of whole genome sequence variants to the phenotypic variation partly depends on their allele frequencies. Common variants associated with different traits have been identified and explain a considerable proportion of the genetic variance. For example, common variants from whole genome sequence associated with longevity have been identified in chapter 5. However, the identified common variants cannot explain the full genetic variance, and rare variants might play an important role here. Rare variants may account for a large proportion of the whole genome sequence variants, but are often ignored in genomic evaluation, partly because of difficulty to identify associations between rare variants and phenotypes. I compared the powers of different gene-based association mapping methods that combine the rare variants within a gene using a simulation study. Those gene- based methods had a higher power for mapping rare variants compared with mixed linear models applying single marker tests that are commonly used for common variants. Moreover, I explored the role of rare and low-frequency variants in the variation of different complex traits and their impact on genomic prediction reliability. Rare and low-frequency variants contributed relatively more to variation for health-related traits than production traits, reflecting the potential of improving prediction reliability using rare and low-frequency variants for health-related traits. However, in practice, only marginal improvement was observed using selected rare and low-frequency variants when combined with 50k SNP genotype data on the reliability of genomic prediction for fertility, longevity and health traits. A simulation study did show that reliability of genomic prediction could be improved provided that causal rare and low-frequency variants affecting a trait are known.

Prospects of whole-genome sequence data in animal and plant breeding
Binsbergen, Rianne van - \ 2017
University. Promotor(en): Roel Veerkamp; Fred van Eeuwijk, co-promotor(en): Mario Calus. - Wageningen : Wageningen University - ISBN 9789463431903 - 220
next generation sequencing - dna sequencing - quantitative trait loci - cattle - genomics - solanum lycopersicum - animal breeding - plant breeding - dna-sequencing - loci voor kwantitatief kenmerk - rundvee - genomica - dierveredeling - plantenveredeling

The rapid decrease in costs of DNA sequencing implies that whole-genome sequence data will be widely available in the coming few years. Whole-genome sequence data includes all base-pairs on the genome that show variation in the sequenced population. Consequently, it is assumed that the causal mutations (e.g. quantitative trait loci; QTL) are included, which allows testing a given trait directly for association with a QTL, and might lead to discovery of new QTL or higher accuracies in genomic predictions compared to currently available marker panels. The main aim of this thesis was to investigate the benefits of using whole-genome sequence data in breeding of animals and plants compared to currently available marker panels. First the potential and benefits of using whole-genome sequence data were studied in (dairy) cattle. Accuracy of genotype imputation to whole-genome sequence data was generally high, depending on the used marker panel. In contrast to the expectations, genomic prediction showed no advantage of using whole-genome sequence data compared to a high density marker panel. Thereafter, the use of whole-genome sequence data for QTL detection in tomato (S. Lycopersicum) was studied. In a recombinant inbred line (RIL) population, more QTL were found when using sequence data compared to a marker panel, while increasing marker density was not expected to provide additional power to detect QTL. Next to the RIL population, also in an association panel it was shown that, even with limited imputation accuracy, the power of a genome-wide association study can be improved by using whole-genome sequence data. For successful application of whole-genome sequence data in animals or plants, genotype imputation will remain important to obtain accurate sequence data for all individuals in a cost effective way. Sequence data will increase the power of QTL detection in RIL populations, association panels or outbred populations. Added value of whole-genome sequence data in genomic prediction will be limited, unless more information is known about the biological background of traits and functional annotations of DNA. Also statistical models that incorporate this information and that can efficiently handle large datasets have to be developed.

Milk progesterone measures to improve genomic selection for fertility in dairy cows
Tenghe, Amabel Manyu Mefru - \ 2017
University. Promotor(en): Roel Veerkamp; B. Berglund, co-promotor(en): D. J. de Koning; Aniek Bouwman. - Wageningen : Wageningen University - ISBN 9789463431330 - 179
dairy cows - fertility - progesterone - milk - genomics - genetic improvement - heritability - genetic parameters - dairy performance - reproductive traits - animal genetics - animal breeding - dairy farming - melkkoeien - vruchtbaarheid - progesteron - melk - genomica - genetische verbetering - genetische parameters - melkresultaten - voortplantingskenmerken - diergenetica - dierveredeling - melkveehouderij

Improved reproductive performance has a substantial benefit for the overall profitability of dairy cattle farming by decreasing insemination and veterinary treatment costs, shortening calving intervals, and lowering the rate of involuntary culling. Unfortunately, the low heritability of classical fertility traits derived from calving and insemination data makes genetic improvement by traditional animal breeding slow. Therefore, there is an interest in finding novel measures of fertility that have a higher heritability or using genomic information to aid genetic selection for fertility. The overall objective of this thesis was to explore the use of milk progesterone (P4) records and genomic information to improve selection for fertility in dairy cows. In a first step, the use of in-line milk progesterone records to define endocrine fertility traits was investigated, and genetic parameters estimated. Several defined endocrine fertility traits were heritable, and showed a reasonable repeatability. Also, the genetic correlation of milk production traits with endocrine fertility traits were considerably lower than the correlations of milk production with classical fertility traits. In the next step 17 quantitative trait loci (QTL) associated with endocrine fertility traits, were identified on Bos taurus autosomes (BTA) 2, 3, 8, 12, 15, 17, 23, and 25 in a genome-wide association study with single nucleotide polymorphisms. Further, fine-mapping of target regions on BTA 2 and 3, identified several associated variants and potential candidate genes underlying endocrine fertility traits. Subsequently, the optimal use of endocrine fertility traits in genomic evaluations was investigated; using empirical and theoretical predictions for single-trait models, I showed that endocrine fertility traits have more predictive ability than classical fertility traits. The accuracy of genomic prediction was also substantially improved when endocrine and classical fertility traits were combined in multi-trait genomic prediction. Finally, using deterministic predictions, the potential accuracy of multi-trait genomic selection when combining a cow training population measured for the endocrine trait commencement of luteal activity (C-LA), with a training population of bulls with daughter observations for a classical fertility trait was investigated. Results showed that for prediction of fertility, there is no benefit of investing in a cow training population when the breeding goal is based on classical fertility traits. However, when considering a more biological breeding goal for fertility like C-LA, accuracy is substantially improved when endocrine traits are available from a limited number of farms.

Selection for pure- and crossbred performance in Charolais
Vallée-Dassonneville, Amélie - \ 2017
University. Promotor(en): Johan van Arendonk; Henk Bovenhuis. - Wageningen : Wageningen University - ISBN 9789463430180 - 151
charolais - cattle - animal breeding - crossbreeding - crossbreds - selection - beef cattle - genomes - genetic parameters - rundvee - dierveredeling - kruisingsfokkerij - kruising - selectie - vleesvee - genomen - genetische parameters

Two categories of beef production exist; i.e. (i) purebred animals from a beef sire and a beef dam and (ii) crossbred animals from a beef sire and a dairy dam.

For the purebred beef production, there is a growing interest to include behavior and type traits in the breeding goal. Heritabilities for behavior traits, estimated using subjective data scored by farmers, range from 0.02 to 0.19. Heritabilities for type traits range from 0.02 to 0.35. Results show that there are good opportunities to implement selection for behavior traits using a simple on-farm recording system to allow collection of large data set, and for type traits in Charolais. A genome-wide association study detected 16 genomic regions with small effect on behavior and type traits. This suggests that behavior and type traits are influenced by many genes each explaining a small part of the genetic variance.

The two main dairy breeds mated to Charolais sires for crossbred beef production in France are Montbéliard and Holstein. The genetic correlation between the same trait measured on Montbéliard x Charolais and on Holstein x Charolais was 0.99 for muscular development, 0.96 for birth weight; and 0.91 for calving difficulty, 0.80 for height, and 0.70 for bone thinness. Thus, for these last three traits, results show evidence for re-ranking of Charolais sires depending on whether they are mated to Montbéliard or Holstein cows. When using genomic prediction, the Montbéliard x Charolais and Holstein x Charolais populations could be combined into a single reference population to increase size and accuracy of genomic prediction. Results indicate that the higher the genetic correlation is between the two crossbred populations, the higher the gain in accuracy is achieved when combining the two populations into a single reference.

The selection of Charolais sires to produce purebred or crossbred animals is made through distinct breeding programs. An alternative could be to combine selection into one breeding program. Decision for combining or keeping breeding programs separate is determined by the correlation between the breeding objectives, the selection intensity, the difference in level of genetic merit, the accuracy of selection, and the recent implementation of genomic evaluation. Considering all parameters and based on estimations for selection on birth weight, I recommend combining both breeding programs because this will lead to higher genetic gain, and might simplify operating organization and reduce associated costs.

Genetische analyse van de Stabij
Doekes, H.P. ; Oldenbroek, J.K. ; Windig, J.J. - \ 2016
Zeldzaam huisdier 41 (2016)1. - ISSN 0929-905X - p. 18 - 19.
zeldzame rassen - genetische analyse - hondenrassen - friese stabij - dierveredeling - rare breeds - genetic analysis - dog breeds - frisian stabyhoun - animal breeding
De Stabij is een van de negen oorspronkelijke Nederlandse hondenrassen die een belangrijke rol vervullen in het Fairfok-programma van de Raad van Beheer voor de Kynologie. De SZH ondersteunt dat programma door de rasverenigingen van kennis en advies te voorzien en heeft met het CGN een genetische analyse gemaakt van het Stabijras.
Genetische analyse van het Markiesje
Doekes, H.P. ; Oldenbroek, J.K. ; Windig, J.J. - \ 2016
Zeldzaam huisdier 41 (2016)2. - ISSN 0929-905X - p. 20 - 21.
hondenrassen - zeldzame rassen - genetische analyse - dierveredeling - stamboeken - dog breeds - rare breeds - genetic analysis - animal breeding - herdbooks
Het Markiesje is een van de negen oorspronkelijke Nederlandse hondenrassen. Het vervult een belangrijke rol in het Fairfok-programma. De SZH ondersteunt dat programma door de rasverenigingen van kennis en advies te voorzien.
Genomic selection in egg-laying chickens
Heidaritabar, M. - \ 2016
University. Promotor(en): Martien Groenen, co-promotor(en): John Bastiaansen. - Wageningen : Wageningen University - ISBN 9789462576704 - 220 p.
hens - genomics - genetic variation - selective breeding - quantitative traits - breeding value - animal genetics - animal breeding - hennen - genomica - genetische variatie - selectief fokken - kwantitatieve kenmerken - fokwaarde - diergenetica - dierveredeling

Abstract

Heidaritabar, M. (2016). Genomic selection in egg-laying chickens. PhD thesis, Wageningen University, the Netherlands

In recent years, prediction of genetic values with DNA markers, or genomic selection (GS), has become a very intense field of research. Many initial studies on GS have focused on the accuracy of predicting the genetic values with different genomic prediction methods. In this thesis, I assessed several aspects of GS. I started with evaluating results of GS against results of traditional pedigree-based selection (BLUP) in data from a selection experiment that applied both methods side by side. The impact of traditional selection and GS on the overall genome variation as well as the overlap between regions selected by GS and the genomic regions predicted to affect the traits were assessed. The impact of selection on genome variation was assessed by measuring changes in allele frequencies that allowed the identification of regions in the genome where changes must be due to selection. These frequency changes were shown to be larger than what could be expected from random fluctuations, indicating that selection is really affecting the allele frequencies and that this effect is stronger in GS compared with BLUP. Next, concordance was tested between the selected regions and regions that affect the traits, as detected by a genome-wide association study. Results showed a low concordance overall between the associated regions and the selected regions. However, markers in associated regions did show larger changes in allele frequencies compared with the average changes across the genome. The selection experiment was performed using a medium density of DNA markers (60K). I subsequently explored the potential benefits of whole-genome sequence data for GS by comparing prediction accuracy from imputed sequence data with the accuracy obtained from the 60K genotypes. Before sequencing, the selection of key animals that should be sequenced to maximize imputation accuracy was assessed with the original 60K genotypes. The accuracy of genotype imputation from lower density panels using a small number of selected key animals as reference was compared with a scenario where random animals were used as the reference population. Even with a very small number of animals as reference, reasonable imputation accuracy could be obtained. Moreover, selecting key animals as reference considerably improved imputation accuracy of rare alleles compared with a set of random reference animals. While imputation from a small reference set was successful, imputation to whole-genome sequence data hardly improved genomic prediction accuracy compared with the predictions based on 60K genotypes. Using only those markers from the whole-genome sequence that are more likely to affect the phenotype was expected to remove noise from the data, but resulted in slightly lower prediction accuracy compared with the complete genome sequence. Finally, I evaluated the inclusion of dominance effects besides additive effects in GS models. The proportion of variance due to additive and dominance effects were estimated for egg production and egg quality traits of a purebred line of layers. The proportion of dominance variance to the total phenotypic variance ranged from 0 to 0.05 across traits. Also, the impact of fitting dominance besides additive effects on prediction accuracy was investigated, but was not found to improve accuracy of genomic prediction of breeding values.

Breeding against infectious diseases in animals
Rashidi, H. - \ 2016
University. Promotor(en): Johan van Arendonk, co-promotor(en): Herman Mulder; P.K. Mathur. - Wageningen University - ISBN 9789462576452 - 179 p.
livestock - infectious diseases - animal breeding - selective breeding - disease resistance - tolerance - genetic variation - breeding value - genetic correlation - traits - genomics - animal genetics - vee - infectieziekten - dierveredeling - selectief fokken - ziekteresistentie - tolerantie - genetische variatie - fokwaarde - genetische correlatie - kenmerken - genomica - diergenetica

Infectious diseases in farm animals are of major concern because of animal welfare, production costs, and public health. Farms undergo huge economic losses due to infectious disease. The costs of infections in farm animals are mainly due to production losses, treatment of infected animals, and disease control strategies. Control strategies, however, are not always successful. Selective breeding for the animals that can mount a defence against infection could therefore be a promising approach. Defensive ability of an animal has two main mechanisms: resistance (ability to control the pathogen burden) and tolerance (ability to maintain performance when pathogen burden increases). When it is difficult to distinguish between resistance and tolerance, defensive ability is measured as resilience that is the ability to maintain performance during a disease outbreak regardless of pathogen burden. Studies have focused on the genetics of resistance and resilience with little known about the genetics of tolerance and its relationship with resistance and resilience. The objectives of this thesis were to: 1) estimate the genetic variation in resistance, tolerance, and resilience to infection in order to assess the amenability of these traits for selective breeding in farm animals, 2) estimate the genetic correlation between resistance, tolerance and resilience and 3) detect genomic regions associated with resistance, tolerance, and resilience.

In chapter 2, we studied the variation among sows in response to porcine reproductive and respiratory syndrome (PRRS). First a statistical method was developed to detect PRRS outbreaks based on reproduction records of sows. The method showed a high sensitivity (78%) for disease phases. Then the variation of sows in response to PRRS was quantified using 2 models on the traits number of piglets born alive (NBA) and number of piglets born dead (LOSS): 1) bivariate model considering the trait in healthy and disease phases as different traits, and 2) reaction norm model modelling the response of sows as a linear regression of the trait on herd-year-week estimates of NBA. Trait correlations between healthy and disease phases deviated from unity (0.57±0.13 – 0.87±0.18). The repeatabilities ranged from 0.07±0.027 to 0.16±0.005. The reaction norm model had higher predictive ability in disease phase compared to the bivariate model.

In chapter 3 we studied 1) the genetic variation in resistance and tolerance of sheep to gastrointestinal nematode infection and 2) the genetic correlation between resistance and tolerance. Sire models on faecal nematode egg count (FEC), IgA, and pepsinogen were used to study the genetic variation in resistance. Heritability for resistance traits ranged from 0.19±0.10 to 0.59±0.20. A random regression model was used to study the reaction norm of sheep body weight on FEC as an estimate of tolerance to nematode infection. We observed a significant genetic variance in tolerance (P<0.05). Finally a bivariate model was used to study the genetic correlation between resistance and tolerance. We observed a negative genetic correlation (-0.63±0.25) between resistance and tolerance.

In chapter 4, we studied the response to selection in resistance and tolerance when using estimated breeding values for resilience. We used Monte Carlo simulation to generate 100 half-sib families with known breeding values for resistance (pathogen burden) and tolerance. We used selection index theory to predict response to selection for resistance and tolerance: 1) when pathogen burden is known and selection is based on true breeding values for resistance and tolerance and 2) when pathogen burden is unknown and selection is based on estimated breeding values for resilience. Using EBV for resilience in absence of records for pathogen burden resulted in favourable responses in resistance and tolerance to infections, with more emphasis on tolerance than on resistance. However, more genetic gain in resistance and tolerance could be achieved when pathogen burden was known.

In chapter 5 we studied genomics regions associated with resistance, resilience, and tolerance to PRRS. Resistance was modelled as sire effect on area under the PRRS viremia curve up to 14 days post infection (AUC14). Resilience was modelled as sire effects on daily growth of pigs up to 28 days post infection (ADG28). Tolerance was modelled as the sire effect on the regression of ADG28 on AUC14. We identified a major genomics region on chromosome 4 associated with resistance and resilience to PRRS. We also identified genomics regions on chromosome 1 associated with tolerance to PRRS.

In the general discussion (chapter 6) I discussed: 1) response to infection as a special case of genotype by environment interaction, 2) random regression model as a statistical tool for studying response to disease, 3) advantages and requirements of random regression models, and 4) selective breeding of farm animals for resistance, tolerance, and resilience to infections. I concluded that random regression is a powerful approach to estimate response to infection in animals. If the adequate amount of data is available random regression model could estimate breeding values of animals more accurately compared to other models. I also concluded that before including resistance and tolerance into breeding programs, breeders should make sure about the added values of including these traits on genetic progress. Selective breeding for resilience could be a pragmatic approach to simultaneously improve resistance and tolerance.

Fokkerij en Voortplantingstechnieken : Anima(l) sana in corpore sano
Ellen, E.D. ; Arendonk, J.A.M. van; Lansbergen, L.M.T.E. ; Meijboom, F. ; Schakenraad, Marc ; Oonk, Maartje - \ 2016
Den Haag : Raad voor Dierenaangelegenheden - 52 p.
dierenwelzijn - dierlijke productie - paarden - gezelschapsdieren - hobbydieren - dierethiek - dierveredeling - diergezondheid - diergedrag - animal welfare - animal production - horses - pets - hobby animals - animal ethics - animal breeding - animal health - animal behaviour
In 2010 publiceerde de Raad voor Dierenaangelegenheden zijn zienswijze Fokkerij en Voortplantingstechnieken. Sinds die tijd zijn er nieuwe technieken ontwikkeld, discussies gevoerd en zijn partijen aan de slag gegaan met het afwegingskader en aanbevelingen uit deze zienswijze. De vraagstukken rond fokkerij en voortplantingstechnieken blijven ook in 2016 actueel. Dit vormt voor de Raad aanleiding om deze actualisatie uit te brengen.
Multi-population genomic prediction
Wientjes, Y.C.J. - \ 2016
University. Promotor(en): Roel Veerkamp; Mario Calus. - Wageningen : Wageningen University - ISBN 9789462576193 - 267 p.
cum laude - dairy cattle - genomics - prediction - quantitative trait loci - genetic improvement - breeding value - selective breeding - animal breeding - animal genetics - melkvee - genomica - voorspelling - loci voor kwantitatief kenmerk - genetische verbetering - fokwaarde - selectief fokken - dierveredeling - diergenetica
Cum laude graduation
Hereditary disorders in pedigree dogs and look-a-likes
Zeeland, C.W.M. Van; Beerda, B. - \ 2015
Wageningen UR, Wetenschapswinkel (Rapport / Wetenschapswinkel Wageningen UR 317) - ISBN 9789461738882 - 51 p.
dogs - dog breeds - genetic disorders - pedigree - disease prevalence - animal breeding - animal welfare - animal health - pets - honden - hondenrassen - genetische stoornissen - stamboom - ziekteprevalentie - dierveredeling - dierenwelzijn - diergezondheid - gezelschapsdieren
Selectie en genetische variatie in een fokprogramma
Oldenbroek, Kor ; Maurice - Van Eijndhoven, Myrthe - \ 2015
Zeldzaam huisdier 40 (2015)4. - ISSN 0929-905X - p. 14 - 17.
dierveredeling - veredelingsprogramma's - genetische variatie - selectie - zeldzame rassen - heritability - inteelt - verwantschap - groninger paard - animal breeding - breeding programmes - genetic variation - selection - rare breeds - inbreeding - kinship - groningen horse
In drie voorgaande artikelen in deze serie zijn achtereenvolgens het fokdoel, de registratie van gegevens en de basisprincipes van de erfelijkheid besproken. In dit laatste artikel wordt het belang van genetische variatie en de selectie van ouderdieren besproken. Twee belangrijke elementen in het fokprogramma van een zeldzaam ras.
Handboek melkveehouderij 2015/16
Remmelink, G.J. ; Middelkoop, J.C. van; Ouweltjes, W. ; Wemmenhove, H. - \ 2015
Wageningen : Wageningen UR Livestock Research (Handboek / Wageningen UR Livestock Research 30) - 386
melkvee - melkveehouderij - bodemeigenschappen - bemesting - graslandbeheer - voedergrassen - voedergewassen - rundveevoeding - dierveredeling - diergezondheid - melkproductie - landbouwbedrijfsgebouwen - nederland - handboeken - dairy cattle - dairy farming - soil properties - fertilizer application - grassland management - fodder grasses - fodder crops - cattle feeding - animal breeding - animal health - milk production - farm buildings - netherlands - handbooks
Natuurlijke antilichamen als voorspeller zieke koe
Knaap, J. van der; Poel, J.J. van der - \ 2015
Veeteelt 32 (2015)15. - ISSN 0168-7565 - p. 10 - 12.
melkveehouderij - dierveredeling - natuurlijke antilichamen - diergezondheid - fokwaarde - dairy farming - animal breeding - natural antibodies - animal health - breeding value
De aanwezigheid van natuurlijke antilichamen, de zogenaamde NAbs, kan sterk verschillen per koe. Door de erfelijkheidsgraad van NAbs is het mogelijk om erop te fokken, zo blijkt uit het project Weerbaar Vee. De uitkomsten bieden perspectief om de gezondheid te verbeteren, maar de uitvoering lijkt nog niet prakijkrijp.
Wat is erfelijkheid?
Maurice - Van Eijndhoven, M.H.T. ; Oldenbroek, Kor - \ 2015
Zeldzaam huisdier 40 (2015)3. - ISSN 0929-905X - p. 10 - 12.
heritability - rassen (dieren) - dierveredeling - dna - eigenschappen - spermatozoön - eicellen - bevruchting - genen - allelen - homozygoten - heterozygoten - mutaties - genetische merkers - breeds - animal breeding - properties - spermatozoa - ova - fertilization - genes - alleles - homozygotes - heterozygotes - mutations - genetic markers
Eigenschappen van dieren zijn in meer of mindere mate erfelijk. Ze gaan over van ouders op nakomelingen. Maar ervaren fokkers weten dat in de fokkerij 1+1 geen 2 is. Welke wetmatigheden en welke toevalligheden spelen een rol in de erfelijkheid? Wat heeft het DNA-onderzoek ons daar recentelijk over geleerd en wat kunnen we daarmee?
Genetic background of claw health in dairy cattle
Spek, D. van der - \ 2015
University. Promotor(en): Johan van Arendonk, co-promotor(en): Henk Bovenhuis. - Wageningen : Wageningen University - ISBN 9789462573475 - 158
melkvee - klauwen - diergezondheid - voetziekten - genetische parameters - heritability - genomica - selectief fokken - dierveredeling - dairy cattle - claws - animal health - foot diseases - genetic parameters - genomics - selective breeding - animal breeding

Abstract

Van der Spek, D. (2015). Genetic background of claw health in dairy cattle. PhD thesis, Wageningen University, the Netherlands.

Claw disorders affect cow welfare and profitability of farms and as such are important traits relevant to dairy cattle breeding. Aim of this thesis was to increase our understanding of the genetic background of claw disorders to enable selection for reduced claw disorder incidence. The claw disorders were: abscess, corkscrew claw, (inter-)digital dermatitis or heel erosion (DER), double sole (DS), hardship groove, interdigital hyperplasia (IH), interdigital phlegmon, sand crack, super-foul, sole hemorrhage (SH), sole injury, sole ulcer (SU), white line separation (WLS), and yellow discoloration of the sole. Data was collected on Holstein cows kept in dairy herds in France. Individual claw disorder frequencies ranged from 0.1% to 23.8% and more than half of the trimmed cows had at least one claw disorder in at least one hind leg between 2007 and 2012. Heritabilities were estimated for DER, DS, IH, SH, SU, and WLS, and ranged from 0.02 to 0.14. Repeatabilities ranged from 0.02 to 0.33. The need for trimming (“trimming status”) was found to be heritable as well with a heritability of 0.09. A high need for trimming the claws of cows is unfavorable and therefore trimming status is an interesting trait to include in genetic evaluation. Most claw health traits had similar heritabilities and were genetically the same trait in different parities, lactation stages and herds with different trait frequencies. Claw disorder frequency in Montbeliarde cows ranged from 9.4% to 41.1% and 73% of the cows had at least one claw disorder in at least one hind leg between 2007 and 2013. Heritabilities ranged from 0.01 to 0.09. Heritability for trimming status was 0.06, confirming that trimming status is a heritable trait.

To identify genomic regions associated with claw disorders and trimming status, a genome wide association study was performed. In total, 11 significant and 46 suggestive SNP were detected. Three of the suggestive SNP could be validated using a dataset of genotyped bulls. The detected SNP were spread across the genome and a major gene was not found.

In the general discussion, alternative ways of measuring claw disorders were discussed. Accuracy of progeny testing and genomic selection for claw disorders was compared and a breeding program to reduce claw disorders was simulated in order to estimate selection response. Reducing the incidence of claw disorders is achievable with selection, but at a cost of a decrease in production.

Non-genetic variance in pigs: genetic analysis of reproduction and production traits
Sell-Kubiak, E.B. - \ 2015
University. Promotor(en): Johan van Arendonk, co-promotor(en): Piter Bijma; Herman Mulder. - Wageningen : Wageningen University - ISBN 9789462573291 - 186
varkens - dierveredeling - voortplanting - dierlijke productie - genetische analyse - genotypische variatie - genomica - fenotypische variatie - pigs - animal breeding - reproduction - animal production - genetic analysis - genetic variance - genomics - phenotypic variation

Abstract

Sell-Kubiak, E. (2015). Non-genetic variance in pigs: genetic analysis of reproduction and production traits. PhD thesis, Wageningen University, The Netherlands

The main objective of this thesis was to study the origin of random variance in reproduction and production traits of pigs. In pig breeding for many traits it is important not only to improve the reproduction and production trait itself, but also its variation. The variance of traits can be used to improve pigs’ productivity, and potentially also to improve uniformity of traits. Results presented in Chapters 2 and 3 show that the proposed approach to explore the origin of common litter variance was not successful. The impact of various sow features on growth rate and feed intake of grow-finish pigs was very small. More importantly, sow features did not explain the phenotypic variance due to common litter effects found in production traits of pigs. In Chapters 4 and 5 the residual variance of birth weight and litter size were found to have a genetic component. The genetic coefficient of variation at residual standard deviation level (GCVSDe) was proposed as a measure of expressing the potential response to selection (Chapter 4). For both traits the estimated GCVSDe was about 10%, indicating sufficient potential for response to selection. In Chapter 4 it was shown that analyzing variation in traits with Double Hierarchical Generalized Linear model (DHGLM) was highly comparable with the conventional analysis of standard deviation of a trait. The correlation between the additive genetic effects for birth weight and the residual variance was 0.6 (Chapter 4), whereas for litter size (TNB) and its residual variance (varTNB) this correlation was 0.5 (Chapter 5). Those moderate correlations are an important indication of the direction of correlated selection response in the mean of those traits. In Chapter 5 in a genome-wide association study for litter size variation, the significant SNPs explained 0.83% of total genetic variance in TNB and 1.44% in varTNB. The most significant SNP explained 0.4% of genetic variance in TNB (chromosome 11) and 0.5% in varTNB (chromosome 7). One of the possible candidate genes for varTNB on chromosome 7 is heat shock protein (HSPCB). Studying the residual variance of traits with DHGLM has a great potential to serve as an alternative to conventional analysis to study and to select for improved uniformity of various traits. Lastly, Chapter 6 focuses on discussion of the findings of this thesis and their overall importance for pig breeding, as well as highly relevant topics for breeding uniform and robust pigs (macro-micro sensitivity analysis and application of genomic selection).

Genetic improvement in indigenous chicken of Ethiopia
Woldegiorgiss, W.E. - \ 2015
University. Promotor(en): Johan van Arendonk, co-promotor(en): Liesbeth van der Waaij; T. Dessie. - Wageningen : Wageningen University - ISBN 9789462573161 - 130
kippen - pluimvee - inheems vee - genetische verbetering - houding van boeren - perceptie - kippenrassen - prestatieniveau - dierveredeling - ethiopië - fowls - poultry - native livestock - genetic improvement - farmers' attitudes - perception - fowl breeds - performance - animal breeding - ethiopia

Abstract

Wondmeneh Esatu Woldegiorgiss (2015). Genetic improvement in indigenous chicken of Ethiopia. PhD thesis, Wageningen University, the Netherlands

This thesis considered various approaches to study the potential for improvement of village poultry production system using improved indigenous chicken. The approaches were structured survey questionnaire, village poultry simulation model (VIPOSIM), Heckman two-step model (econometric model), and experiments involving laboratory and field. First factors that determine the probability and intensity of adoption of exotic chickens were assessed. The probability of adopting exotic chickens was found to be positively affected by access to an off-farm income and negatively by livestock income. The intensity of adoption was negatively affected by being male household head, having a larger farm size, and having livestock income. Then, perceptions of farmers towards village poultry and impacts of interventions on flock and economic performance were assessed. Farmers’ perceptions affected their decisions about implementation of interventions, and interventions increased productivity but only in a few cases the increased revenues outweighed the additional costs. Subsequently, the evaluation of the breeds was conducted by comparing the natural antibody and productivity of improved indigenous chicken with crossbred, commercial and unimproved indigenous chickens. The results revealed that not only the NAb levels but also the effect of NAbs on survival differ between indigenous and improved breeds. NAb levels are associated with survival in commercial layer breed, but reduced survival in indigenous chickens placed in confinement. Improved indigenous chickens showed higher performance than unimproved one for all traits measured on-station, but remains lighter and developed more into a laying type than meat through the short-term selective breeding program. Overall, the present studies indicate that interventions need to be tailored towards the local situation to ensure that they lead not only to improved productivity but also to improved income.

Breeding program for indigenous chicken in Kenya
Ngeno, K. - \ 2015
University. Promotor(en): Johan van Arendonk, co-promotor(en): Liesbeth van der Waaij; A.K. Kahi. - Wageningen : Wageningen University - ISBN 9789462572775 - 154
kippen - pluimvee - inheems vee - dierveredeling - veredelingsprogramma's - genetische diversiteit - ecotypen - genomen - genetische verbetering - kenya - fowls - poultry - native livestock - animal breeding - breeding programmes - genetic diversity - ecotypes - genomes - genetic improvement

Abstract

Ngeno, K. (2015). Breeding program for indigenous chicken in Kenya. Analysis of diversity in indigenous chicken populations. PhD thesis, Wageningen University, the Netherlands

The objective of this research was to generate knowledge required for the development of an indigenous chicken (IC) breeding program for enhanced productivity and improved human livelihood in Kenya. The initial step was to review five questions; what, why and how should we conserve IC in an effective and sustainable way, who are the stakeholders and what are their roles in the IC breeding program. The next step of the research focused on detecting distinctive IC ecotypes through morphological and genomic characterization. Indigenous chicken ecotypes were found to be populations with huge variability in the morphological features. Molecular characterization was carried out using microsatellite markers and whole genome re-sequenced data. The studied IC ecotypes are genetically distinct groups. The MHC-linked microsatellite markers divided the eight IC ecotypes studied into three mixed clusters, composing of individuals from the different ecotypes whereas non-MHC markers grouped ICs into two groups. Analysis revealed high genetic variation within the ecotype with highly diverse MHC-linked alleles which are known to be involved in disease resistance. Whole genome re-sequencing revealed genomic variability, regions affected by selection, candidate genes and mutations that can explain partially the phenotypic divergence between IC and commercial layers. Unlike commercial chickens, IC preserved a high genomic variability that may be important in addressing present and future challenges associated with environmental adaptation and farmers’ breeding goals. Lastly, this study showed that there is an opportunity to improve IC through selection within the population. Genetic improvement utilizing within IC selection requires setting up a breeding program. The study described the systematic and logical steps in designing a breeding program by focusing on farmers’ need, how to improve IC to fit the farming conditions, and management regimes.

The hybrid nature of pig genomes : unraveling the mosaic haplotype structure in wild and commercial Sus scrofa populations
Bosse, M. - \ 2015
University. Promotor(en): Martien Groenen, co-promotor(en): Hendrik-Jan Megens; Ole Madsen. - Wageningen : Wageningen University - ISBN 9789462573000 - 253
dieren - varkens - dierveredeling - genomen - hybridisatie - sus scrofa - haplotypen - genomica - populaties - genetische variatie - animals - pigs - animal breeding - genomes - hybridization - haplotypes - genomics - populations - genetic variation - cum laude
cum laude graduation
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