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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Impact of human activities on the reproduction of Hooded Vultures Necrosyrtes monachus in Burkina Faso
Daboné, Clément ; Buij, Ralph ; Oueda, Adama ; Adjakpa, Jacques Boko ; Guenda, Wendengoudi ; Weesie, Peter D.M. - \ 2019
Ostrich 90 (2019)1. - ISSN 0030-6525 - p. 53 - 61.
Burkina Faso - conservation - Hooded Vulture - human impact - reproduction

During the last decades, the critically endangered Hooded Vulture Necrosyrtes monachus has strongly declined across its African range. Although direct persecution has been suggested as a major cause of this decline, little is known about the impact of humans on reproductive output in West Africa. We studied the impact of human activities on the reproductive output of Hooded Vultures in the Garango area of Burkina Faso. Twenty and 56 nesting attempts were monitored, respectively, during the breeding season in 2013/14 and 2014/15, to determine reproductive success and identify causes of nest failure. Annual breeding success varied between 0.68 and 0.71 chicks fledged per breeding pair per year and productivity was assessed at 0.57 chicks fledged per territorial pair in 2014/15. The main threats imposed by humans were poaching of eggs, chicks and collection of nest materials, leading to 20% (13 out of 64 breeding attempts) of nest failures over the two years. An additional important reason for nest failure was the pruning and (partial) cutting of nest trees. Despite this high level of human interference, we found that Hooded Vulture nest success increased with proximity to human settlements, probably because breeding vultures benefit from protection by people against persecution and disturbance.

Differential effects of climate warming on reproduction and functional responses on insects in the fourth trophic level
Chen, Cong ; Gols, Rieta ; Biere, Arjen ; Harvey, Jeffrey A. - \ 2019
Functional Ecology 33 (2019)4. - ISSN 0269-8463 - p. 693 - 702.
anthropogenic global warming - functional responses - host - hyperparasitoids - parasitoid interactions - parasitoids - reproduction

Understanding the effects of anthropogenic global warming (AGW) on species interactions is essential for predicting community responses to climate change. However, while effects of AGW on resource–consumer interactions at the first and second trophic level have been well studied, little is known about effects on interactions at higher trophic levels at the terminal end of food chains (e.g. in the third and fourth trophic levels). Here, we examined the effects of temperature variability by simulating heatwaves on functional responses of two species at the fourth trophic level (hyperparasitoids) that parasitize host species at the third trophic level (parasitoid cocoons). We found that host cocoons developed faster under simulated heatwave conditions, decreasing the temporal window of susceptibility of the host cocoons to parasitism by the two hyperparasitoids, and consequently parasitism declined with temperature. However, the effects of a simulated heatwave markedly differed among the two hyperparasitoid species; temperature and host quality had a much stronger effect on early reproduction in the less fecund hyperparasitoid Gelis agilis, than in the more fecund species Acrolyta nens. Our results suggest that exposure to heatwaves, that are expected to increase in frequency, will affect the ability of species at higher trophic levels to exploit transient resources whose suitability is temperature-dependent. In turn, the observed effects of AGW on the functional responses of the hyperparasitoids may disrupt trophic interactions and have profound impact on population dynamics and ecological processes. A plain language summary is available for this article.

Follicular development of sows at weaning in relation to estimated breeding value for within-litter variation in piglet birth weight
Costermans, N.G.J. ; Teerds, K.J. ; Keijer, J. ; Knol, E.F. ; Koopmanschap, R.E. ; Kemp, B. ; Soede, N.M. - \ 2019
Animal 13 (2019)3. - ISSN 1751-7311 - p. 554 - 563.
lactation - litter uniformity - metabolism - reproduction - sows

In this study we aimed to identify possible causes of within-litter variation in piglet birth weight (birth weight variation) by studying follicular development of sows at weaning in relation to their estimated breeding value (EBV) for birth weight variation. In total, 29 multiparous sows (parity 3 to 5) were selected on their EBV for birth weight variation (SD in grams; High-EBV: 15.8±1.6, N=14 and Low-EBV: −24.7±1.5, N=15). The two groups of sows had similar litter sizes (15.7 v. 16.9). Within 24 h after parturition, piglets were cross-fostered to ensure 13 suckling piglets per sow. Sows weaned 12.8±1.0 and 12.7±1.0 piglets, respectively, at days 26.1±0.2 of lactation. Blood and ovaries were collected within 2 h after weaning. The right ovary was immediately frozen to assess average follicle size and percentage healthy follicles of the 15 largest follicles. The left ovary was used to assess the percentage morphologically healthy cumulus-oocyte complexes (COCs) of the 15 largest follicles. To assess the metabolic state of the sows, body condition and the circulating metabolic markers insulin, IGF1, non-esterified fatty acid, creatinine, leptin, urea and fibroblast growth factor 21 were analysed at weaning. No significant differences were found in any of the measured follicular or metabolic parameters between High-EBV and Low-EBV. A higher weight loss during lactation was related to a lower percentage healthy COCs (β= −0.65, P=0.02). Serum creatinine, a marker for protein breakdown, was negatively related to average follicle size (β= −0.60, P=0.05). Backfat loss during lactation was related to a higher backfat thickness at parturition and to a higher average follicle size (β=0.36, P<0.001) at weaning. In conclusion, we hypothesise that modern hybrid sows with more backfat at the start of lactation are able to mobilise more energy from backfat during lactation and could thereby spare protein reserves to support follicular development.

Hox gene expression profiles during embryonic development of common sole
Kavouras, Menelaos ; Malandrakis, Emmanouil E. ; Golomazou, Eleni ; Konstantinidis, Ioannis ; Blom, Ewout ; Palstra, Arjan P. ; Anastassiadis, Konstantinos ; Panagiotaki, Panagiota ; Exadactylos, Athanasios - \ 2018
Animal Biology (2018). - ISSN 1570-7555 - 16 p.
Broodstock - egg quality - homeobox genes - reproduction - Solea solea
Common sole (Solea solea) aquaculture production is based mostly on wild-caught breeders. Recently, the successful reproduction of first-generation fish that were reared in captivity was accomplished. A consistent good quality and quantity of produced eggs throughout the year, and of next-generationbroodstock, is important for reducing the overall cost of production. Hox genes play a pivotal role in normal embryonic development and alterations of their temporal expression level may be important for egg viability. Expression profile analysis of five hox genes (hoxa1a, hoxa2a, hoxa2b, hoxb1a and hoxb1b) involved in early embryonic development and of hoxa13a, which is involved in late stages, was carried out. Results revealed a premature and/or maternal expression of hoxa13a in sole embryos,and the detection of hoxa2a and hoxa2b genes as members of paralog group 2. Principal Component Analysis of hox gene expression in 54 ± 6 hours post fertilization embryos coming from wild-caught broodstock and a first-generation one reared in the hatchery, unveiled that these broodstocks are clearly distinct. In addition, their pairwise comparison revealed significant differences in the expression levels of hoxb1a and hoxb1b genes. Hox gene regulation during embryonic development could give valuable insight into rearing sole broodstocks with different origin in concert, and also into gaining a steady mass production of eggs, either in quality or quantity, all year round.
Effects of dietary protein level and age at photo stimulation on reproduction traits of broiler breeders and progeny performance
Emous, R.A. van; Cruz, C.E. de la; Naranjo, V.D. - \ 2018
Poultry Science 97 (2018)6. - ISSN 0032-5791 - p. 1968 - 1979.
age at photo stimulation - broiler breeder - dietary crude protein - progeny - reproduction

A study with a 2 × 2 factorial arrangement was conducted to determine the effects of 2 dietary crude protein levels, high (CPh) or low (CPl), supplemented with free amino acids (AA), and 2 ages at photo stimulation (PS) - early (21 wk; PSe) or late (23 wk; PSl) - on reproduction traits of broiler breeders and progeny performance. Diets were isocaloric, and calculated CP content of the CPl diets was 15 g/kg lower than the CPh diets during all phases. A total of 480 female and 64 male Ross 308 breeders of 20 wk of age were used. Total egg production was similar between CPl and CPh birds during phase 1 and 2 but was reduced by 2.8 eggs for CPl birds during phase 3. For the overall laying period, CPl birds tended (P = 0.075) to produce 4.7 fewer total eggs. Hatchability of set eggs was similar between CPl and CPh birds during phases 1 and 2 but tended (P = 0.064) to be lower for CPl birds in phase 3. PSe birds showed an advanced age at sexual maturity and age at peak production of 4.6 and 5.3 d, respectively, resulting in 2.5 more total eggs during phase 1. During phase 1, PSe birds showed an almost 5% increased fertility. Chick production in phase 1 was higher for PSe birds resulting in a tendency (P = 0.071) to higher overall chick production of almost 8 chicks. Progeny from early PS breeders showed an overall significant lower feed conversion ratio (FCR). It was concluded that egg and chick production during phases 1 and 2 were not affected by dietary CP level, but egg and chick production was reduced for CPl birds during phase 3. On the other hand, PSe birds showed an increased number of chicks. It is possible to decrease CP level of breeder diets with comparable reproduction from 22 to 46 wk; however, this is questionable for phase 3. For maximal chick production, early PS is recommended.

Reproductive adaptations to reduce locomotor costs in viviparous fish (Poeciliidae)
Fleuren, Mike - \ 2017
Wageningen University. Promotor(en): Johan van Leeuwen, co-promotor(en): Bart Pollux. - Wageningen : Wageningen University - ISBN 9789463438025 - 204
fishes - poeciliidae - reproduction - adaptation - vivipary - locomotion - biomechanics - zoology - vissen - voortplanting - adaptatie - levendbarend - voortbeweging - biomechanica - zoölogie

Viviparity, a live-bearing mode of reproduction, has evolved over 100 times independently in vertebrate animals. Despite its frequent evolution, viviparity has a number of hypothesised disadvantages compared to the ancestral mode of reproduction, oviparity (egg-laying). One of these disadvantages is a reduction in locomotor performance during pregnancy, the period of internal development of the embryos. Adaptations to a live-bearing reproductive mode could have evolved to reduce these locomotor costs. In this thesis, I aim to find whether matrotrophy, post-fertilization nutrient provisioning (e.g. through a placental structure), and superfetation, the presence of multiple broods of different developmental stages, reduce the locomotor performance decline during pregnancy in the Poeciliidae, live-bearing fishes.

In Chapter 2, we review the literature on the effects of pregnancy on morphology, performance and fitness. The biomechanics of each mode of locomotion (walking, swimming or flying) are distinct, and are affected differently by the added mass and volume of pregnancy. Furthermore, we list the possible adaptations that have evolved to reduce the locomotor costs of pregnancy, and divide them into three different categories: adaptations that reduce the locomotor costs of live-bearing, adaptations with which the locomotor costs of live-bearing are avoided, and adaptations to the life history of the animal. Lastly, we discuss hiatuses in the literature and experimental procedures to quantify the hypothesised benefit of adaptations.

In Chapter 3, we compare the morphological changes during pregnancy in two closely-related species of live-bearing fish: Poeciliopsis turneri and Poeciliopsis gracilis. These species mainly differ in their mode of nutrient provisioning: P. gracilis is lecithotrophic and P. turneri is an extensive matrotroph. We tracked the morphological changes in 3D using a non-invasive method that creates three-dimensional body models. We find that P. turneri is more slender during the early stages of pregnancy, but increase in size more rapidly. This is in line with the locomotor costs hypothesis, which predicts that matrotrophic fish are more slender during the early stages of pregnancy, but that the difference between the body shapes of lecithotrophic and matrotrophic fish diminishes as pregnancy progresses. Our results indicate that matrotrophy could indeed provide a morphological advantage during pregnancy.

Fast-start performance, a manoeuvre fish deploy to escape predatory strikes, is important for individual survival. In Chapter 4, we use state-of-the-art biomechanical methods to, for the first time, quantify this manoeuvre in three-dimensional space in adult fish (Heterandria formosa). We show that fish can orient their escapes in up- and downwards direction, and that this is correlated with a change in pitch angle of the body. Changes in roll angle of the body were not correlated with orientation of the fish. We furthermore demonstrate that stage 1 of the fast start, often described as a preparatory stage, can already contribute to propulsion. The results from Chapter 4 indicate that three-dimensional measurements of fast-start manoeuvres provide novel insights that were often overlooked.

Measuring fast starts in three-dimensional space is relevant in determining the adverse effects of pregnancy on locomotor performance. We did this by comparing three species of live-bearing fish: P. turneri, H. formosa and Phalloptychus januarius. In Chapter 5, we show that pregnancy-induced changes in abdominal width are correlated with a reduction in performance in the horizontal plane (maximal horizontal speed, change in yaw angle), but less so in the vertical plane (maximal vertical speed, change in pitch angle). Furthermore, we demonstrate that an increase in abdominal width is correlated with a decrease in abdominal curvature and, for some species, in a decrease in maximal curvature rate in the abdomen. Lastly, we show that the pregnancy-induced morphological changes depend on the level of superfetation: species with a high level of superfetation experience higher frequency, but smaller amplitude changes in the shape of the abdomen. Whether superfetation actually results in a more slender body shape, as predicted by the locomotor costs hypothesis, depends on the level of reproductive investment.

In this thesis, I show that pregnancy induces changes in morphology which comes with a cost in fast-start performance. Both matrotrophy and superfetation affect how body shape changes due to pregnancy, but whether the latter provides beneficial changes depends on the level of reproductive investment. Furthermore, I reveal that fast starts can have a substantial three-dimensional component which is relevant both to biomechanicists that aim to understand the physical and physiological mechanisms underlying this manoeuvre and to evolutionary biologists that strive to answer performance-related questions.

On the genetic mechanisms of nutrient-dependent lifespan and reproduction
Zandveld, Jelle - \ 2017
Wageningen University. Promotor(en): Bas Zwaan, co-promotor(en): Fons Debets. - Wageningen : Wageningen University - ISBN 9789463436861 - 209
genetics - lifespan - reproduction - nutrients - drosophila melanogaster - fungi - diet - evolution - genetica - levensduur - voortplanting - voedingsstoffen - schimmels - dieet - evolutie

Dietary restriction (DR), a moderate reduction in nutrient intake, improves health or extends lifespan across many species. Moreover, recent insights have shown that also the effects of specific nutrients are of importance for the beneficial effects of DR rather than intake alone. However, we still lack much insight through what mechanisms the lifespan increase through diet changes is exactly mediated.

To further increase our understanding of the genetic mechanisms of nutrient-dependent lifespan, in Chapter 2, 3, 4, and 5 I employed different methods of genetic interventions (i.e. a genetic knockout, natural genetic variation and experimental evolution) using the model species Drosophila melanogaster and Podospora anserina. To test whether the genetic interventions affected the diet response, a broad range of diets was applied, thereby taking the recent insights of nutritional geometry into account. Furthermore, the response of the fly’s whole-genome transcription to different dietary treatments were assessed in Chapter 6 and 7 to identify and potentially disentangle genetic mechanisms for lifespan from those for reproduction.

Chapter 2 addressed the effects of a triple knockout in the insulin-IGF signalling (IIS) pathway, namely for three genes encoding insulin-like peptides in Drosophila (dilp2-3,5). The mutant showed a strong elevation of lifespan that was irrespective of food type, but also a strong reduction of the female fly fecundity. In addition, this assay also revealed that the same knockout can yield different interpretations for its function in the fly’s diet response, which was strongly dependent per diet dimension under consideration (i.e. varying yeast, sugar, or its ratio in the diet). This observation set the stage for other experimental chapters in this thesis, where a broad range of diets was applied to depict the exact genotypic effects that are involved in the lifespan response to diet. For example, in Chapter 2, interactive effects were observed between dilp2-3,5 knockout and the lifespan response to dietary sugar, but however, not for the yeast component of the diet.

In Chapter 3, for the same experimental diets, gene expression responses in dilp2-3,5 knockout flies were measured to describe the general dynamics on the pathway level. Interestingly, expression of the remaining fly head-expressed dilp, dilp6, was elevated on higher yeast levels upon dilp2-3,5 knockout. Therefore, compensatory mechanisms within IIS might still partly mediate the lifespan response to yeast.

In Chapter 4 the natural genetic variation for the response to DR was explored in wild-derived strains of the fungus Podospora anserina. By applying a broad range of glucose concentrations in a synthetic medium, we constructed reaction norms for 62 natural occurring strains and showed considerable natural variation in the shape of the reaction norms, including the glucose concentration at which lifespan increased and how steeply the fungus’ lifespan responds to diet (the slope S). Furthermore, I identified a significant correlation between a strain’s general lifespan and both parameters, suggesting that the lifespan response to diet partly acts through a mechanism involved in the fungus’ lifespan determination under high nutrient, growth and reproduction permissive, conditions. On moderate glucose restriction levels we showed that a reduced reproduction was not always associated with lifespan extension, which indicates that decoupling of these traits (that often trade-off) can be achieved.

An evolutionary perspective on diet response and the connection between reproduction and lifespan, two often interconnected traits in lifespan research, was provided in Chapter 5. Here, experimental evolution (EE) was performed in Drosophila melanogaster to test whether improved reproductive capacity (i.e. local adaptation) to three nutritionally distinct diets directly affected the lifespan response. Adaptation to the distinct nutritional conditions, had no consistent effect on the lifespan response to diet. Other life-history traits that I assessed could more consistently be associated with the evolutionary nutritional treatments, which together suggested that the adaptive genetic mechanisms increasing the fly’s reproduction were not necessarily interconnected singly with a change of lifespan, but rather with a change in the whole life-history strategy.

By exploring the fly’s whole-genome transcription response in a continuously changing environ­ment, Chapter 6 continued on the evolutionary relevance of lifespan responses to diet. This type of fluctuations may better reflect the fly’s natural ecological setting than the continuous diets typically applied in whole-genome transcription laboratory studies. This revealed that flies were able to respond quickly to diet fluctuations throughout lifespan by drastically changing their transcription pattern and, moreover, my results indicated that a large part of the whole-genome transcription response could be attributed to the female fly’s reproduction. Because I measured the response of multiple life-history traits to the fluctuating diet changes, I was able to decouple groups of genes associated with lifespan from those associated with reproduction. This is an important step in the direction of unravelling the genetic architecture that specifically mediates the lifespan response to diet, which can be especially useful in whole-genome transcription studies.

In Chapter 7, the consistencies between studies for their whole-genome transcription responses upon DR were investigated. This revealed large transcriptomic variations on different regulatory levels, i.e. the level of whole-genome transcription, most significant genes, and also gene ontology. To test whether the observed inconsistent whole-genome transcription responses were primarily a reflection of the fly’s reproduction, such as observed in Chapter 6, a new cohort of flies was subjected to different regimes that resulted in very different age-dependent reproduction patterns. By assessing whole-genome transcription in this cohort at two time points, the gene expression changes reflected the age-dependent reproduction patterns observed, rather than the lifespan phenotypes. Similar to Chapter 6, this again highlighted the importance of measuring multiple life-history traits for associating whole-genome transcription responses to lifespan effects of dietary restriction.

In Chapter 8 the acquired insights across the experimental chapters were synthesized, discussing the importance of assessing a broad range of nutrients for the interpretation of any genotypic effect, and in addition discussing the value of measuring multiple life-history traits for genetic associations. In this chapter I also suggested directions for future research in Drosophila and Podospora that may be valuable for further unravelling and understanding the mechanisms of diet responses in other organisms, including in humans.

The utility of sensor technology to support reproductive management on dairy farms
Rutten, C.J. - \ 2017
Wageningen University. Promotor(en): Henk Hogeveen; Michel Nielen, co-promotor(en): Wilma Steeneveld. - Wageningen : Wageningen University - ISBN 9789463431934 - 232
dairy cattle - dairy farms - sensors - reproduction - reproductive behaviour - animal health - calving - activity - management - dairy farming - technology - agricultural economics - melkvee - melkveebedrijven - voortplanting - voortplantingsgedrag - diergezondheid - kalven - activiteit - bedrijfsvoering - melkveehouderij - technologie - agrarische economie

Since the 1980s, efforts have been made to develop sensors that measure a parameter from an individual cow. The development started with individual cow recognition and was followed by sensors that measure the electrical conductivity of milk and pedometers that measure activity. Some sensors like activity meters, electrical conductivity, weight floors and somatic cell count sensors are commercially available. Adoption has in general been low and mainly driven by the AMS, with a clear exception for estrus detection. In practice, the economic benefits of using sensor systems has not been proven. So, to make sensors live up to their full potential there is a need for research to shift from technical development towards practical applications and integration with operational farm management. Estrus detection sensors can have a good detection performance and are currently applied by farmers in practice, therefore this thesis focusses on sensors that support reproductive management. The main objective of this thesis is to study the utility of sensor technology to support reproductive management on dairy farms. This main objective was split in five sub objectives that each study a part of the main objective and were discussed in the separate chapters of this thesis.

We demonstrated that utility of sensors for reproductive management can be found in economic benefits (estrus and calving detection), reduction of labor (calving and estrus detection) and more detailed management information (prognosis of insemination success). So, automated estrus detection aids reproductive management.

From this thesis the following conclusions can be drawn:

The developed theoretical framework describes four levels of sensor development, which should all be included in proper development of sensor systems. The literature review showed that no studies developed sensor systems with regard to management and decision support.

It was possible to improve the prediction of the start of calving compared to a model that only uses the expected calving date. However, predicting the start of calving within an hour was not possible with a high sensitivity and specificity.

There was financial merit in the use of calving detection, because the sensor system enables more timely intervention by the farmer. The uncertainty about the positive effects was large, which caused a wide range in the simulated financial benefits.

Investment in a sensor for estrus detection was on average profitable with a return on investment of 11%. Profitability was influenced most by the heuristic culling rules and the expected increase of the estrus detection rate between detection by visual observation and the sensor.

Routinely collected farm data can be used to estimate a prognosis on insemination success and be used to determine whether an individual cow has a higher or lower than average likelihood of insemination success. Integration of this prognostic model with an estrus detection sensor has potential.

Currently farmers only adopt sensors for estrus detection or because they were standard with an AMS. A reason for this is that sensor systems do not produce clear information for farmers. Sensor technology should be focused on management support of applications. Labor benefits of sensors are important for adoption of sensors by farmers, farmers value flexibility, increased family time and less physical workload as benefits. However, economic evaluations of technical solutions are unable to quantify these benefits. Sensor research should consider the preference of farmers regarding labor. For the appraisal of sensor technology new methods to value labor benefits of sensor are needed. Furthermore, in sensor development societal acceptance should be an important consideration. Animal rights activists may frame the use of sensors as a form of industrialized farming. Only using technical arguments and considerations to explain the benefits of sensors will hamper the societal acceptance of modern dairy farming. Application of sensors on dairy farms should be communicated smartly to society in terms that relate the values of citizens.

Data from: Context-dependent effects of radio transmitter attachment on a small passerine
Snijders, L. ; Nieuwe Weme, L.E. ; Goede, Piet de; Savage, J.L. ; Oers, Kees van; Naguib, M. - \ 2016
biotelemetry - passerine - reproduction - Parus major
Biotelemetry devices provide unprecedented insights into the spatial behaviour and ecology of many animals. Quantifying the potential effects of attaching such devices to animals is essential, but certain effects may appear only in specific or particularly stressful contexts. Here we analyse the effects of radio transmitter attachment on great tits Parus major tagged over three environmentally dissimilar years, as part of a project studying social- and communication networks. When we radio-tagged birds before breeding, only those tagged in the coldest spring tended to be less likely to breed than control birds. Breeding probability was independent of relative transmitter weight (between 5 and 8% bodyweight). When we radio-tagged both parents during nestling provisioning (transmitter weight between 6 and 8%), tagged parents were more likely than control parents to desert their brood in two out of three years, while in the other year no tagged parents deserted. Tagged parents provisioning larger broods were most likely to desert, especially during lower average temperatures. Video analyses did not reveal any transmitter effects on provisioning behaviour of parents in the year with no desertion. We conclude that radio tagging before breeding did not lead to negative effects, regardless of transmitter weight, but that decisions about radio-tagging both parents during nestling provisioning need to be made with exceptional care, taking both environmental context and transmitter weight into account. Reporting results from long-term radio-tracking studies comprising several environmentally variable years is crucial to understand and predict potential transmitter effects and maximise the tremendous potential of biotelemetry.
Energy status and ovarian follicular development
Meng, Li - \ 2016
Wageningen University. Promotor(en): Jaap Keijer; Katja Teerds. - Wageningen : Wageningen University - ISBN 9789462579170 - 144
ovarian development - energy - follicles - reproduction - atresia - development - ovaries - ovariumontwikkeling - energie - follikels - voortplanting - atresie - ontwikkeling - ovaria

Female reproduction is tightly linked to body energy status and it has become increasingly clear that disturbed energy metabolism can negatively affect reproductive performance. Nevertheless, the way how a disturbed energy status affects ovarian follicular reserve as well as follicular recruitment and growth is little investigated and not fully elucidated. Therefore, the overall goal of this thesis was to investigate the effects of an altered metabolism, and particularly an altered energy status, on ovarian follicular development. To achieve this goal, the first aim was to establish the role of autophagy in follicular degeneration under normal physiological conditions, with focus on preantral and antral follicles; The second aim was to elucidate the effects of a diet-induced reduction in thyroid hormone concentrations, affecting whole body metabolism, on ovarian follicular development; The third aim was to investigate the effect of an increased nutrient flux towards skeletal muscle on ovarian follicular development and the possible underlying mechanism.

It is well known that granulosa cell death via apoptosis is the main cause of atresia of antral follicles, however, whether preantral follicular attrition makes use of the same cell death pathway is not clear. Therefore, in chapter 2 I have investigated different cell death pathways in the adult rat ovary to examine whether they represent the reported histological differences between preantral and antral atretic follicles. Based on the results of studies in other organs, I used microtubule-associated light-chain protein 3 (LC3) and QSQTM1/p62 as markers of autophagy and cleaved caspase 3 (cCASP3) as marker of apoptosis, using immunohistochemistry, western blotting, and laser capture micro-dissection followed by qRT-PCR. The results showed that in the granulosa cells of atretic preantral follicles, p62 immunostaining was less intense compared to healthy preantral follicles, while no difference in LC3 immunostaining intensity was observed. In contrast, in antral follicles, no difference in both immunostaining and mRNA levels of LC3 and p62 were found between healthy and atretic follicles, indicating that autophagy was not responsible for attrition of antral follicles. cCASP3 immunostaining was scarce in the granulosa cells of atretic preantral follicles, whereas many cCASP3 positive apoptotic cells were present in atretic antral follicles, indicating that apoptosis is a major cell death pathway activated in antral follicle degeneration. Immunostaining for superoxide dismutase 2 (SOD2) was reduced in preantral and antral atretic follicles. This observation was confirmed by a concomitant down regulation of Sod2 mRNA levels. These findings suggest that preantral follicular atresia mainly makes use of autophagy as cell death pathway, while antral follicles degenerate mainly via apoptosis.

In chapter 3, the consequences of prolonged exposure to reduced thyroid hormone concentrations in adulthood on the size of the ovarian follicle pool are investigated. Besides having a direct effect on the functioning of many cells, changes in thyroid hormone levels also influence metabolism. In this study female rats at the age of 10 weeks were given a control diet or an iodide deficient diet in combination with perchlorate supplementation to inhibit iodide uptake by the thyroid, resulting in a relatively mild chronic hypothyroid condition. At the age of 26 weeks animals were sacrificed and ovaries histologically evaluated. Plasma concentrations of relevant hormones (thyroid-stimulating hormone (TSH), tri-iodothyronine (T3), thyroxine (T4), follicle-stimulating hormone (FSH), luteinizing hormone (LH) and anti-Müllerian hormone (AMH) were determined. Primordial, primary and preantral follicle numbers were significantly lower in the hypothyroid ovaries compared to the euthyroid controls, while a downward trend in antral follicle numbers and corpora lutea was observed. The percentage of atretic follicles was not different between the two groups. Plasma AMH concentrations showed a significant correlation with the growing follicle population represented by the total number of primary, preantral and antral follicles per ovary. The data indicate that prolonged mild hypothyroidism negatively affects ovarian follicular reserve as well as the size of the growing follicle population, which may impact fertility. AMH can serve, also under mild hypothyroid conditions, as a surrogate marker to assess the size of the growing ovarian follicle population, offering a non-invasive way to evaluate the correlation between female reproductive health and thyroid status.

Subsequently, in chapter 4, the long-term effects of chronic hypothyroidism initiated already in the foetal/neonatal period on ovarian follicular development were investigated. In contrast to the experiments described in chapter 3, the rats in this experiment were exposed to reduced thyroid hormone levels from the moment of conception until necropsy. Effects on the ovarian follicular reserve and ovulation rate in prepubertal (12-day-old) and adult (64-day-old and 120-day-old) rats were studied. Besides, antioxidant gene expression, mitochondrial density and the occurrence of oxidative stress were analyzed. The results of this investigation showed that continuous fetal/postnatal hypothyroidism resulted in lower preantral and antral follicle numbers in adulthood, accompanied by a higher percentage of atretic follicles, when compared to euthyroid age-matched controls. Not surprisingly, ovulation rate was lower in the hypothyroid rats. At the age of 120 days, the mRNA and protein content of superoxide dismutase 1 (SOD1) was significantly increased, while catalase (CAT) mRNA and protein content was significantly decreased, suggesting a disturbed antioxidant defense capacity of ovarian cells in the hypothyroid animals. This was supported by a significant reduction in peroxiredoxin 3 (Prdx3), thioredoxin reductase 1 (Txnrd1), and uncoupling protein 2 (Ucp2) mRNA content and a downward trend in glutathione peroxidase 3 (Gpx3) and glutathione S-transferase mu 2 (Gstm2) mRNA content. These changes in gene expression were likely responsible for the increased immunostaining of the oxidative stress marker 4-hydroxynonenal. Together these results suggest that chronic hypothyroidism initiated in the foetal/neonatal period resulted in a decreased ovulation rate associated with a disturbance of the antioxidant defense system in the ovary. In contrast to hypothyroidism induced in adulthood (chapter 3), no reduction in primordial or primary follicle numbers was observed, suggesting that the ovarian reserve was not affected.

Chapter 5 addressed the question what the consequences were of a change in nutrient flux on ovarian follicular development. In this chapter mice were employed that ectopically express uncoupling protein 1 (UCP1) in skeletal muscle (UCP1-TG). This did not affect adiposity, but led to a redistribution of energy sources away from the ovaries towards skeletal muscle tissue,; a model of skeletal muscle pseudo-starvation. The results showed that UCP1-TG female mice had increased energy expenditure, reduced body size, unchanged adiposity, increased plasma fibroblast growth factor 21 (FGF21) concentrations and reduced insulin-like growth factor 1 (IGF1) levels. UCP1-TG mice had a 30% lower number of healthy follicle compared to WT mice. Primary and preantral follicle numbers were decreased by 40%, while the number of atretic follicles was significantly increased and corpora lutea (CL) were absent in 40% of the ovaries of UCP1-TG mice. The latter suggested that these mice did not ovulate and thus were infertile. The elevated circulating FGF21 concentrations were not responsible for the ovarian phenotype, since UCP1-TG and UCP1-TG/FG21-/- mice show the same ovarian follicular phenotype. Significant correlation of circulating IGF1 levels with antral follicle, CL numbers and differentially activated AKT in healthy antral follicles and activated IRS2 in atretic follicles between WT and UCP1-TG mice shows, that IGF1 is, at least partly, responsible for the ovarian phenotype of these mice. Together, our data show that an energy drain towards skeletal muscle tissue negatively impacts growing pool of ovarian follicles and ovulation rate in female mice, which is, at least in part, mediated by IGF1, and not by FGF21.

In conclusion, the results of my thesis research shows that preantral atresia occurs mainly through autophagy. Dietary induced chronic hypothyroidism, an intervention that reduces basal metabolic rate, initiated either during foetal/neonatal or adulthood impairs ovarian follicle development. The age at onset of hypothyroidism modified the effects of this condition on ovarian follicular development. A change in nutrient flux away from the ovaries towards skeletal muscle tissue negatively affects ovarian follicle development. Overall, the results of my thesis have provided new insights in the mechanisms of follicular attrition and shows that conditions that alter metabolic fuel use impact on ovarian follicular development.

Demographic Changes Underpinning the Population Decline of Starlings Sturnus vulgaris in the Netherlands
Versluijs, Martijn ; Turnhout, Chris A.M. van; Kleijn, David ; Jeugd, Henk P. van der - \ 2016
Ardea 104 (2016)2. - ISSN 0373-2266 - p. 153 - 165.
LTRE - mark-recovery - population matrix model - reproduction - survival

Declines in farmland bird populations are often linked to changes in agricultural practices, but little is known about the demographic changes underlying these adverse trends. Identifying the demographic drivers of population change is critical for understanding why populations are declining. In this study we assessed the demographic changes in the declining Dutch Starling Sturnus vulgaris population. We estimated productivity per breeding attempt and survival rates over a period of 52 years (1960-2012). The results show that juvenile survival decreased significantly over time. Adult survival fluctuated between years, with (non-significant) lower survival rates between 1990 and 2012. No trend in reproductive output was found over the study period. A population model was built for three different phases of population change within the study period: 1960-1978, 1978-1990 and 1990-2012. The contribution of changes in demographic parameters to population growth rate (lambda) between the different periods was examined by performing a life table response experiment (LTRE). The LTRE analysis showed that changes in juvenile survival explained most of the differences in population growth rate between periods. Our results therefore suggest that a decline in juvenile survival rather than changes in adult survival or reproductive success is the most important cause of the decline of the Starling population in The Netherlands.

Puberende paling wil niet volwassen worden
Palstra, Arjan - \ 2016
eels - eel culture - captive animals - fish culture - reproduction

In gevangenschap planten palingen zich nog niet voort. Wageningen UR kan al wel opgekweekte paling in de puberteit brengen.

Olfaction: An Overlooked Sensory Modality in Applied Ethology and Animal Welfare
Nielsen, B.L. ; Jezierski, T. ; Bolhuis, J.E. ; Amo, L. ; Rosell, F. ; Oostindjer, M. ; Christensen, J.W. ; Mckeegan, D. ; Wells, D.L. ; Hepper, P. - \ 2015
Frontiers in Veterinary Science 2 (2015)69. - ISSN 2297-1769
odors - chemoreception - behavior - feeding - stress - housing - reproduction - disease
Diploid males support a two-step mechanism of endosymbiont-induced thelytoky in a parasitoid wasp
Ma, W.J. ; Pannebakker, B.A. ; Zande, L. van de; Schwander, T. ; Wertheim, B. ; Beukeboom, L.W. - \ 2015
BMC Evolutionary Biology 15 (2015). - ISSN 1471-2148
leptopilina-clavipes hymenoptera - sex-determination - parthenogenetic populations - quantitative pcr - insect sex - wolbachia - host - reproduction - braconidae - determines
Background Haplodiploidy, where females develop from diploid, fertilized eggs and males from haploid, unfertilized eggs, is abundant in some insect lineages. Some species in these lineages reproduce by thelytoky that is caused by infection with endosymbionts: infected females lay haploid eggs that undergo diploidization and develop into females, while males are very rare or absent. It is generally assumed that in thelytokous wasps, endosymbionts merely diploidize the unfertilized eggs, which would then trigger female development. Results We found that females in the parasitoid wasp Asobara japonica infected with thelytoky-inducing Wolbachia produce 0.7–1.2 % male offspring. Seven to 39 % of these males are diploid, indicating that diploidization and female development can be uncoupled in A. japonica. Wolbachia titer in adults was correlated with their ploidy and sex: diploids carried much higher Wolbachia titers than haploids, and diploid females carried more Wolbachia than diploid males. Data from introgression lines indicated that the development of diploid individuals into males instead of females is not caused by malfunction-mutations in the host genome but that diploid males are most likely produced when the endosymbiont fails to activate the female sex determination pathway. Our data therefore support a two-step mechanism by which endosymbionts induce thelytoky in A. japonica: diploidization of the unfertilized egg is followed by feminization, whereby each step correlates with a threshold of endosymbiont titer during wasp development. Conclusions Our new model of endosymbiont-induced thelytoky overthrows the view that certain sex determination mechanisms constrain the evolution of endosymbiont-induced thelytoky in hymenopteran insects. Endosymbionts can cause parthenogenesis through feminization, even in groups in which endosymbiont-diploidized eggs would develop into males following the hosts’ sex determination mechanism. In addition, our model broadens our understanding of the mechanisms by which endosymbionts induce thelytoky to enhance their transmission to the next generation. Importantly, it also provides a novel window to study the yet-poorly known haplodiploid sex determination mechanisms in haplodiploid insects.
Non-genetic variance in pigs: genetic analysis of reproduction and production traits
Sell-Kubiak, E.B. - \ 2015
Wageningen 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


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).

Karyotype evolution in apomictic Boechera and the origin of the aberrant chromosomes
Mandáková, T. ; Schranz, M.E. ; Sharbel, T.F. ; Jong, J.H.S.G.M. de; Lysak, M. - \ 2015
The Plant Journal 82 (2015)5. - ISSN 0960-7412 - p. 785 - 793.
holboellii complex - genus boechera - genome sequence - centric fission - brassicaceae - arabidopsis - centromere - phylogeny - arabis - reproduction
Chromosome rearrangements may result in both decrease and increase of chromosome numbers. Here we have used comparative chromosome painting (CCP) to reconstruct the pathways of descending and ascending dysploidy in the genus Boechera (tribe Boechereae, Brassicaceae). We describe the origin and structure of three Boechera genomes and establish the origin of the previously described aberrant Het and Del chromosomes found in Boechera apomicts with euploid (2n = 14) and aneuploid (2n = 15) chromosome number. CCP analysis allowed us to reconstruct the origin of seven chromosomes in sexual B. stricta and apomictic B. divaricarpa from the ancestral karyotype (n = 8) of Brassicaceae lineage I. Whereas three chromosomes (BS4, BS6, and BS7) retained their ancestral structure, five chromosomes were reshuffled by reciprocal translocations to form chromosomes BS1-BS3 and BS5. The reduction of the chromosome number (from x = 8 to x = 7) was accomplished through the inactivation of a paleocentromere on chromosome BS5. In apomictic 2n = 14 plants, CCP identifies the largely heterochromatic chromosome (Het) being one of the BS1 homologues with the expansion of pericentromeric heterochromatin. In apomictic B. polyantha (2n = 15), the Het has undergone a centric fission resulting in two smaller chromosomes – the submetacentric Het' and telocentric Del. Here we show that new chromosomes can be formed by a centric fission and can be fixed in populations due to the apomictic mode of reproduction.
Mackerel winter spawning surveys 2014 - 2015 December survey
Damme, C.J.G. van; O'Hea, B. - \ 2015
IJmuiden : IMARES (Report / IMARES Wageningen UR C043/15) - 12
scomber scombrus - makrelen - kuitschieten - voortplanting - visbestand - pelagische visserij - mariene ecologie - monitoring - mackerels - spawning - reproduction - fishery resources - pelagic fishery - marine ecology
In recent years the western Atlantic mackerel stock has expanded, resulting in an earlier start of spawning and earlier occurrence of the mackerel peak of spawning. In 2014 and 2015, mackerel winter spawning surveys have been conducted to determine the start date of mackerel spawning in the western area. During the surveys both plankton sampling and trawl hauls are carried out. This report contains the results of the December 2014 survey, carried out on board the Nida.
Mackerel winter spawning surveys 2014 - 2015 January survey: Survey report
Damme, C.J.G. van; Holst, G. - \ 2015
IJmuiden : IMARES (Report / IMARES Wageningen UR C014/15) - 12
scomber scombrus - makrelen - kuitschieten - voortplanting - visbestand - pelagische visserij - mariene ecologie - monitoring - mackerels - spawning - reproduction - fishery resources - pelagic fishery - marine ecology
In recent years the western Atlantic mackerel stock has expanded, resulting in an earlier start of spawning and earlier occurrence of the mackerel peak of spawning. In 2014 and 2015, mackerel winter spawning surveys have been conducted to determine the start date of mackerel spawning in the western area. During the surveys both plankton sampling and trawl hauls are carried out. This report contains the results of the January 2015 survey, carried out on board the CETON S205.
The role of the starfish (Asterias rubens L.) predation in blue mussel (Mytilus edulis L.) seedbed stability
Agüera García, A. - \ 2015
Wageningen University. Promotor(en): Aad Smaal, co-promotor(en): Jeroen Jansen; Tim Schellekens. - Wageningen : Wageningen University - ISBN 9789462572164 - 170
mytilus edulis - mossels - voortplanting - predatie - zaaibedden - predator prooi verhoudingen - waddenzee - aquacultuur - mussels - reproduction - predation - seedbeds - predator prey relationships - wadden sea - aquaculture


Mussel beds are an important ecological component in the Wadden Sea. Mussels’ offspring settle massively in new suitable areas, forming seedbeds that may disappear again within months. The probability of a seedbed to survive the first winter is defined as seedbed stability; a definition that plays a very important role in the management of newly settled seedbeds. Many factors are important in the survival or extinction of seedbeds. Predation is thought to be particularly important during the first year after settlement and therefore key to survival. Many predators feed on mussel beds, but for most of them the potential to exterminate a seedbed is restricted by different factors such as prey selection or competition. Common starfish (Asterias rubens) are capable of concentrating/aggregating in high densities on mussel seedbeds making them an especially important factor limiting/affecting survival of mussel seedbeds. This study assesses the capacities of starfish as a mussel seed predator. It also provides tools and information to assess the risks of a seedbed being attacked and exterminated by starfish.

In Chapter 2 the role of temperature and shading on winter predation was studied. The results showed that temperature limits feeding rate and feeding activity of starfish during winter. However, starfish feeding rate exhibited very high sensitivity to temperature changes. Light intensity affected both feeding rate and feeding activity. We conclude that starfish may not be an important factor destabilizing seedbeds during the average winter, but its importance may grow along with the increasing mean winter temperature due to climate change.

In Chapter 3 the impact of salinity changes on predation performance and survival was assessed. Salinity is the main driver of species distributions in the Wadden Sea. Results show that salinity affected predation performance by reducing feeding activity and causing changes in prey selection. Moreover, as acclimation occurred, A. rubens predation performance improved in all treatments with survivors. We conclude that osmotic stress due to a salinity decreases determines A. rubens distribution, abundance and potential impact on the prey population. However this effect is influenced by the magnitude of the change in salinity and its timescale.

In Chapter 4 the effect of tidal currents on predation rate was assessed, however, the chapter also tackles the role of hydrodynamic stress amelioration by mussels on the A. rubens population. The results suggest that mussels interact with their own predator beyond the role of food source, by ameliorating environmental stress, creating an additional dependence link between the foundation species and the predator, which potentially has major implications for ecosystem structure and stability.

In Chapter 5, we assessed the role of mussel association with conspecifics at high densities on prey selection by A. rubens. We concluded that size selection does not always lead to an improvement in net profit. Size selection is a trade-off between energy yield and predation energy costs, which is affected by prey behaviour.

The results of the prior chapters were integrated in Chapter 6 with field observations and literature to develop a simulation model. This model was designed to simulate growth of mussels and starfish, predation by starfish and mussel mortality. It can also be used to predict the likely effect of future environmental change scenarios on the potential impact of A. rubens on this important resource.

In the general discussion, Chapter 7, previous literature, field data and the results from this thesis are summarised and reviewed to explain the spatial distribution of A. rubens in the Wadden Sea and the role of environmental conditions on A. rubens predation rate. Model simulations are used to answer the question: What is the role of A. rubens predation in mussel seedbed stability?

Body composition and reproduction in broiler breeders: impact of feeding strategies
Emous, R.A. van - \ 2015
Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): Rene Kwakkel; Marinus van Krimpen. - Wageningen : Wageningen University - ISBN 9789462572386 - 173
vleeskuikenouderdieren - vleeskuikens - lichaamssamenstelling - gevogeltevoeding - voer - voedingseiwit - voeropname - diergedrag - corticosteron - voortplanting - vrouwelijke vruchtbaarheid - prestatieniveau - diervoeding - broiler breeders - broilers - body composition - fowl feeding - feeds - dietary protein - feed intake - animal behaviour - corticosterone - reproduction - female fertility - performance - animal nutrition


Key words: broiler breeder, feeding strategies, body composition, reproduction, behavior

Nowadays, welfare issues in broiler breeders associated with nutrition and reproductive characteristics, are becoming increasingly challenging. Due to genetic selection on broilers, body composition of breeders has changed dramatically during the last 50 years to less fat and more breast muscle. It is postulated that a certain amount of body fat in broiler breeders at the onset of lay is necessary for maximum performance and offspring quality. Body composition of breeders can be influenced by different feed allowances during rearing and lay, as well as by changes in nutrient composition of the diet. However, little is known about the effects of body composition on reproduction of broiler breeders. In this thesis, we investigated the effects of different feeding strategies during the rearing period on body composition at the end of rearing. Moreover, the effects of differences in body composition at the end of rearing, and feeding strategies during lay were evaluated on breeder performance, incubation traits, offspring performance, behavior and feather cover. From this study, it can be concluded that feeding a low protein diet during rearing decreased breast muscle and increased abdominal fat pad, whereas providing an increased feeding schedule, which resulted in a high growth pattern, only increased abdominal fat pad, at the end of rearing. The higher abdominal fat pad content resulted in an increased hatchability during the first phase of lay and a larger number of eggs during the second phase of lay. For maintaining growth pattern, broiler breeders had to provide a higher amount of feed with an increased energy to protein ratio compared to broiler breeders that were fed a diet with a standard energy to protein ratio. This resulted in an increased eating time and less stereotypic object pecking, which may indicate a reduced hunger and frustration. On the other hand, a low daily protein intake during the rearing and first phase of lay can lead to a poor feather cover. Feeding a high-energy diet during the second phase of lay resulted in increased hatchability, decreased embryonic mortality and more first grade chicks.

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