Pim Brascamp

• PhD
• Professor Emeritus at Wageningen University & Research

This is the German translation of Genetics of Selection in Honeybees. The booklet deals with the theory of selection and the design of selection programs. Chapters are breeding goal, quantitative genetics, breeding value estimation and selection. The theory is intended to be presented such that it training in quantitative genetics is not a prerequi...

The book explains the genetics of selection in honeybees for a readership not specialized in quantitative genetics but involved in the development or coordination of breeding programs in honey bees.

Honeybee breeding is organized around annual cycles, following seasonal change. Generation intervals are thus commonly multiples of whole years. Most queens are generally raised during spring or early summer in temperate climates. A generation interval of 1 year limits phenotyping to early recordable traits, before the spring following queens' birt...

There is growing interest in selective breeding of the honeybee, resulting in the emergence of new breeding projects, often with an emphasis on improving resilience traits, in particular toward brood diseases. Lately, feed autonomy is also gaining importance. Here, we use data from a small breeding nucleus in France to estimate genetic parameters f...

Background Breeding queens may be mated with drones that are produced by a single drone-producing queen (DPQ), or a group of sister-DPQs, but often only the dam of the DPQ(s) is reported in the pedigree. Furthermore, datasets may include colony phenotypes from DPQs that were open-mated at different locations, and thus to a heterogeneous drone popul...

Background With the increased number of honeybee breeding plans worldwide, records from queens with diversified mating strategies need to be considered. Breeding queens might be inseminated with drones produced by a single drone-producing queen (DPQ), or by a group of sister-DPQs. Often, only the dam of DPQ(s) is reported in the pedigree. Furthermo...

This article continues our series on the basics of honey bee breeding (Uzunov et al., 2017, 2022a, 2022b). Its purpose is to introduce the background and application of breeding values in honey bees to a readership that is not trained in quantitative genetics. Breeding values are currently not widely used in honey bee breeding. This is in contrast...

This article mainly focuses on the challenges associated with implementing mating control and is the next in line of the series on the concepts of honey bee breeding programs that puzzle many beekeepers around the globe (Uzunov et al., 2017, 2022). A few years after initiating a breeding program, the honey bee breeders and beekeepers mastered the...

As usual in science, where one answer raises new questions, following our attempt to demystify the basic concept of honey bee breeding with our article The Basic Concept of Honey Bee Breeding Programs (Uzunov et al., 2017) questions were raised on details about the implementation of a breeding program. Aspects, such as prioritisation of the traits...

Genetic parameters in honeybees are commonly estimated using ReML methodologies applied to animal models with maternal effects. These methodologies were adapted to the species’ peculiarities, including: phenotypes measured on colonies, haplo-diploïdy and polyandrous mating. However, estimations’ reliability is hindered by the small size of the bree...

For the development of novel selection traits in honey bees, applicability under field conditions is crucial. We thus evaluated two novel traits intended to provide resistance against the ectoparasitic mite Varroa destructor and to allow for their straightforward implementation in honey bee selection. These traits are new field estimates of already...

Infestation with Varroa destructor is a serious cause of bee colony (Apis mellifera) losses on a global level. However, the presence of untreated survivor populations in many different regions supports the idea that selection for resistance can be successful. As colony survival is difficult or impossible to measure, differences in mite infestation...

Infestation with the parasitic mite Varroa destructor is a serious cause of bee colony (Apis mellifera) losses on a global level. However, the presence of untreated survivor populations in many different regions indicates that selection for resistance might lead to a long-term solution. The success of selection depends on suitable testing criteria....

Honey bees are under pressure due to abnormal high colony death rates, especially during the winter. The infestation by the Varroa destructor mite and the viruses that this ectoparasite transmits are generally considered as the bees’ most important biological threats. Almost all efforts to remedy this dual infection have so far focused on the contr...

Successful honey bee breeding programmes require traits that can be genetically improved by selection. Heritabilities for production, behaviour, and health traits, as well as their phenotypic correlations, were estimated in two distinct Swiss Apis mellifera mellifera and Apis mellifera carnica populations based on 9 years of performance records and...

Background: In honey bees, observations are usually made on colonies. The phenotype of a colony is affected by the average breeding value for the worker effect of the thousands of workers in the colony (the worker group) and by the breeding value for the queen effect of the queen of the colony. Because the worker group consists of multiple individ...

The poster presents software that can be used to estimate genetic parameters in honey bees for a variety of populations structures.

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...

Estimation of breeding values of Carnica is now 10 years underway in the Netherlands. The paper shows the annual improvement in average breeding values over time.

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.

The purpose of this paper was to get an orientation estimate of the genetic improvement that can be achieved applying genomics in honey bees. Firstly we simulated a common breeding programme that was supplemented by genomic preselection of queens before phenotyping of their colonies and preselection of drone-producing queens. We found additional an...

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 ver...

International Bee Research Association - IBRA September 1 “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 in participating in many international projects, both beekeepers and bee expe...

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., proge...

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 colon...

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 d...

Abstract Text: Estimation of breeding values and variance components in honey bees is complex due to bees’ reproduction system. It complicates calculation of the numerator relationships matrix (NRM). Mixed model methodology to estimate breeding values in honey bees was developed by Bienefeld (2007) (BER). To invert NRM they used a diagonal matrix...

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 vo...

The effect of costs on the optimum breeding plan for selection for milk traits and the profitability of performance-test selection according to meat production were studied, including the consequences of beef crossing. Returns from breeding schemes were calculated from the expression of genetic superiority of selected parents (paths) in subsequent...

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 b...

Due to genotype by environment interac- tion (GxE), conventional bulls might not be suita ble for organic production circumstances. Therefore, lactation records from Holstein cows on organic and conventional farms were used to estimate the magni- tude of GxE between organic and conventional pro- duction circumstances. GxE was quantified by est i- m...

In an experimental cross between Meishan and Dutch Large White and Landrace lines, 785 F2 animals with carcass information and their parents were typed for molecular markers covering the entire porcine genome. Linkage was studied between these markers and eight meat quality traits. Quantitative trait locus analyses were performed using interval map...

A genome scan was performed on F2 animals of a cross between Meishan and Dutch commercial pigs. Phenotypic data were available for growth traits and ultrasonic backfat thickness on 942–1151 animals, and for litter size on 249 and 206 animals at first and second parity, respectively. QTL analyses were performed using interval mapping by regression u...

A whole-genome scan was conducted using 132 microsatellite markers to identify chromosomal regions that have an effect on teat number. For this purpose, an experimental cross between Chinese Meishan pigs and five commercial Dutch pig lines was used. Linkage analyses were performed using interval mapping by regression under line cross models includi...

The role of imprinting in body composition was investigated in an experimental cross between Chinese Meishan pigs and commercial Dutch pigs. A whole-genome scan revealed significant evidence for five quantitative trait loci (QTL) affecting body composition, of which four were imprinted. Imprinting was tested with a statistical model that separated...

One of the conditions for sustainable cattle production is the long term availability of breeding stock which meets sustainable breeding goals. This paper is limited to dairy cattle production. Sustainable breeding goals pay proper attention to all traits relevant from an economic, social and environmental point of view. In practice this implies br...

Gewaarschuwd wordt tegen de nadelige gevolgen van inteelt in de veefokkerij en wel met name tegen de inteelt bij een kleine populatieomvang

To determine relative impact of genetic, common-litter, and within-litter factors on puppy mortality. 2,622 Boxer puppies of 413 litters born during a 14-month period. For each puppy, pedigree was determined, and litter in which it was born was registered. Overall mortality and mortality per specific cause of death were analyzed by use of a model t...

In an experimental cross between Meishan and Dutch Large White and Landrace lines, 619 F(2) animals and their parents were typed for molecular markers covering the entire porcine genome. Associations were studied between these markers and two fatness traits: intramuscular fat content and backfat thickness. Association analyses were performed using...

The commercially grown broiler usually is a crossbred from specialized purebred sire and dam lines. The position of a purebred line in the crossbreeding system influences its genetic contribution to expression of productive and reproductive performance at different stages of the production column and, thus, influences the breeding goal for a given...

The objectives of this study were to derive economic values in broiler breeding and to determine their relationship with production circumstances. Economic values were derived using a deterministic economic model based on profit equations with a fixed amount of broiler meat output of the production system. Nonintegrated and the integrated broiler p...

The objective of this study was to evaluate relationships between rebreeding performance and growth performance (n = 3,777 gilts) and rebreeding performance and reproductive performance (n = 2,242 sows). Our data were from a selection experiment for shorter intervals from weaning to estrus after the first parity (IWE), involving Dutch Landrace pigs...

In the first part of a data set on elbow dysplasia in dogs (n=188) variance components and breeding values of animals were computed. Observations in the second part (n=65) were subsequently regressed on estimated breeding values. A direct effects model was found inappropriate: although a high heritability was found (0.53), regression of new observa...

The ability to produce large numbers of embryos of high genetic quality in vitro allows new, more efficient breeding schemes and faster dissemination of genetic gain from breeding populations to commercial populations. Whereas ovum pick-up techniques, in combination with in vitro maturation and fertilization of aspirated oocytes, mainly contribute...

This paper discusses changes in the structure of breeding programmes and reasons for these changes. In dairy cattle breeding the most important technological driving force for such changes is reproductive technology, increasing the possible number of offspring per female. An important second factor is the implementation of improved procedures to pr...

Presence of major genes was investigated for two growth traits, backfat thickness, and two litter size traits in the F1 and F2 population of a cross between Meishan and European "White" pig lines. Segregation analyses were performed in a Bayesian setting, estimating the contribution of background polygenes and the contribution of a possible major g...

Presence of single genes affecting meat quality traits was investigated in F2 individuals of a cross between Chinese Meishan and Western pig lines using phenotypic measurements on 11 traits. A Bayesian approach was used for inference about a mixed model of inheritance, postulating effects of polygenic background genes, action of a biallelic autosom...

To obtain estimates of breeding values by BLUP using Henderson's mixed-model equations, it is necessary to invert the covariance matrix for each random effect in the model. In a model in which the genotypic value is included as a random effect (genotypic model), it is necessary to invert the genotypic covariance matrix. Under additive inheritance,...

A selection experiment with a selection and a control line maintained for eight generations was set up to study efficacy of selection for a short interval from weaning to estrus after weaning the first litter and to estimate genetic variation in the Dutch Landrace population. Intervals were recorded without truncation (i.e., intervals up to 234 d w...

In this study genetic parameters of linear scored conformation traits of the Dutch Warmblood Riding Horse were estimated in relation to performance in competition. Observations on 10 665 mares were analyzed with an animal model including the fixed effects age, classifier, location and percentage of thoroughbred. Using restricted maximum likelihood...

Disease resistance results from different processes which partly are immunological in nature. Immunological processes can be subdivided into innate (non-specific) resistance (phagocytosis) and acquired resistance. The latter can be subdivided in cellular and humoral immunity. These three compartments of the immune system do not act independently bu...

Alternative index procedures for selection on non-linear profit are quadratic indices, desired gains indices, group or mate selection indices, or direct optimization of responses over multiple generations. In this study a multiple generation time horizon was considered and several linear, quadratic and desired gains indices were compared. Genetic a...

In this paper a method is outlined to derive marginal-income functions and to calculate economic values for traits with an intermediate optimum such as meat-quality traits. A normal distribution of the quality trait was assumed, but the method can be used for other distributions as well. The parameters necessary to use this method are distribution...

Returns from the utilization of genetic markers in breeding programs have been computed in two ways. In the first approach, returns accrue from additionally improved milk yield that was due to marker utilization in selection. In the second approach, changes in returns from semen sales for a breeding organization operating in a competitive market ar...

A dynamic probabilistic PC-model is used to compare six management strategies on reproduction and replacement in sow herds. The model uses the Markov chain approach to simulate herd dynamics, and derives from that technical and economic results of the herd. Under the circumstances studied, strategies based on the use of an economic culling index I...

A performance test of pigs was conducted according to an adapted version of the ‘Kielanowski system’ in which the feeding level and the termination point of the test period were changed. A total of 119 pigs of six genotypes (participants in the Commercial Pig Evaluation in The Netherlands, 1981) averaging 22 kg weight, were fed for 17 weeks on a sc...

The use of profit equations for deriving economic weights (the value per unit improvement in a trait) in the genetic improvement of livestock has led to anomalies both in theory and in practice. These anomalies can be removed by imposing two conditions. One is that any extra profit from genetic change that can be matched by rescaling the size of th...

Two experiments were carried out to investigate the effects of restricted feeding during the growing (up to 60 kg) and finishing period (from 60 kg to slaughter weight) on the overall performance and composition of pigs. In the first experiment 246 pigs were kept four to a pen. Feeding during the growing as well as the finishing period was either a...

In pig breeding programmes breeding values for growth and carcass traits are generally estimated in test environments, e.g. central test or on-farm test. The breeding goal, however, should be defined at the level of commercial growing. Genotype × environment (G × E) interaction (test and commercial environment) will lower the efficiency of a breedi...

The economic weights derived from profit equations depend on the base used for the evaluation. Thus different relative economic weights are obtained per unit of investment, per breeding female, per individual or per unit of product. This has led to uncertainty and confusion about appropriate economic weights in livestock improvement, and to apparen...

In the 1st of 2 experiments to evaluate different methods of estimating body composition in the growing pig, 80 castrated Dutch Large White X Dutch Landrace [male] piglets, from 16 litters and aged 10-11 wk, were assigned to 14 treatment groups involving various combinations of housing system (in metabolic cages, in groups in a calorimeter, or indi...

The theory of restricted selection indices (where the aim is a genetic change of zero in some traits) and selection indices with desired gains (where relative changes in all traits under selection are prespecified) is discussed in the framework of the general theory of selection indices where some traits are to be changed according to their relativ...

The present working group report is based on questionnaires returned from 17 European countries in the beginning of 1978. It gives information on testing procedures and combinations of these, the breeding goal, variates recorded, how they are recorded, how indices are presented and finally the direction of the genetic gain.No information has been c...