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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Eindrapportage Veerkracht van Melkvee I : verandering van dynamiek, voorspellende kracht
Dixhoorn, Ingrid van; Mol, Rudi de; Werf, Joop van der; Reenen, Kees van - \ 2016
Wageningen : Wageningen UR Livestock Research (Livestock Research rapport 956) - 94
melkkoeien - melkvee - gustperiode - lactatie - rundveeziekten - diergezondheid - diergedrag - dierfysiologie - gegevens verzamelen - voorspelling - rundveeteelt - dairy cows - dairy cattle - dry period - lactation - cattle diseases - animal health - animal behaviour - animal physiology - data collection - prediction - cattle farming
The transition period is a critical phase in the life of dairy cows. Early identification of cows at risk for disease would allow for early intervention and optimization of the transition period. Based on the theory of resilience of biological systems we hypothesize that the level of vulnerability of an individual cow can be quantified by describing dynamical aspects of continuously measured physiological and behavioural variables. To examine the relationship between the risk to develop diseases early in lactation and dynamic patterns of high-resolution, physiological and behavioural data, were continuously recorded in individual cows before calving. Dynamic, quantitative parameters for high-resolution physiological and behavioural measures, continuously acquired during the dry period have predictive value for the risk of cows to develop diseases during the early lactation period. Our results suggest that quantitative parameters derived from sensor data may reflect the level of resilience of individual cows.
Effects of temperature and CO2 during late incubation on broiler chicken development
Maatjens, C.M. - \ 2016
University. Promotor(en): Bas Kemp, co-promotor(en): Henry van den Brand; I.A.M. van Roovert-Reijrink. - Wageningen : Wageningen University - ISBN 9789462578258 - 196 p.
broilers - embryonic development - temperature - carbon dioxide - incubation - animal physiology - broiler performance - artificial hatching - hatcheries - poultry farming - vleeskuikens - embryonale ontwikkeling - temperatuur - kooldioxide - broeden - dierfysiologie - vleeskuikenresultaten - kunstmatig bebroeden - broedinstallaties - pluimveehouderij

Incubation conditions need to be adjusted to meet embryonic requirements to obtain optimal chick quality and hatchability. Eggshell temperature (EST) can be used as a non- invasive method to determine embryo temperature. A high EST of 38.9°C during the second or third week of incubation negatively affects chicken embryo development and survival compared to a constant EST of 37.8°C during that period. These negative effects of high EST might be due to a dis-balance between metabolic rate and oxygen (O2) availability. However, effects of lowering EST, which might restore the balance between metabolic rate and O2 availability, are largely unknown. Besides EST, the carbon dioxide (CO2) concentration during late incubation also seems to affect embryo development and might even interact with EST. Based on the potential effects of (lower) EST during the last week of incubation and of CO2 during only the hatching phase, the following three aims are derived: 1, to investigate effects of EST during the last phase of the incubation process, with special attention for EST below the general accepted optimal EST of 37.8°C, 2, to examine from which day of the incubation process onward EST should be changed from 37.8°C, and 3, to investigate whether CO2 concentrations are interacting with EST during the hatcher phase.

Time until hatch was longer when an EST of 35.6°C was applied during the last week of incubation, followed by 36.7, 37.8, and 38.9°C, which is probably caused by the lower metabolic rate at an EST below 37.8°C. Hatchability of fertile eggs was not affected at low EST, and EST did not affect time between internal pipping (IP) and hatch. An EST of 35.6 and 36.7°C, resulted in a higher yolk-free body mass (YFBM) at hatch compared to 37.8 and 38.9°C, and residual yolk weight was higher at hatch at 38.9°C compared to all other EST treatments. An EST of 35.6°C resulted in higher hepatic glycogen concentration and amount at IP and hatch compared to all other EST treatments. The proposed mechanism involved is that at lower EST, metabolic rate is reduced, which prevents the embryo from O2 limitation and ensures that fatty acid oxidation from the yolk can be maintained, resulting in energy production to be invested in growth and development. At an EST of 38.9°C, metabolic rate is high, resulting in a relative O2 shortage for the embryo. Consequently, lipid oxidation is reduced, which forces the embryo to switch to alternative energy sources, such as glycogen. Because glycogen storage is very limited in the egg and embryo, alternative energy sources such as amino acids obtained from muscles might be used. A clear interaction between EST and start day of treatment was found for relative heart weight. Relative heart weight was higher at an EST of 35.6°C and decreased with increase in EST. The differences among EST became larger when the EST treatment started earlier.

Effects of CO2 on embryo physiology, embryonic organ development, and chick quality were marginal. EST interacted with CO2 mainly before IP, but effects were minor at hatch. Interactions between EST and CO2 were found at an EST of 36.7 and 37.8°C, but remained absent at an EST of 38.9°C, which might indicate that physiological systems are already challenged due to the higher metabolic rate, which limits the capacity to cope with high CO2 of the embryo.

No effect of start day of treatment was indicated for embryonic organ development and chick quality found at hatch, which suggests that EST affected these parameters only in the last phase of incubation, e.g. from E19 onward. However, first week post-hatch performance was affected by start day of treatment. The beneficial effects of a lower EST of 35.6 and 36.7°C applied during the last week of incubation found at hatch, might contribute to an enhanced development during the first week post-hatch as body weight, carcass weight, and gain to feed ratio were increased.

In conclusion, results of this thesis show that an EST below 37.8°C during late incubation is beneficial for embryo development, organ growth during incubation, and growth performance during the first week post-hatch. In addition, start day of treatment did not affect chick quality and organ growth, except heart weight, at hatch, which implies that effects of EST occur during the hatching phase, e.g. from E19 onward. Although, an effect of start day of treatment was found on first week post-hatch performance, it remains to be investigated whether an EST below 37.8°C leads to improved later life quality characteristics.

Het effect van een verhoogde ammoniak concentratie in het water op fysiologie, groei en voeropname van Europese paling (Anguilla anguilla)
Abbink, W. ; Blom, E. ; Pelgrim, Thamar ; Vries, P. de; Vis, J.W. van de; Schram, E. - \ 2015
Yerseke : IMARES (Rapport / IMARES C187/15) - 18 p.
european eels - ammoniak - dierfysiologie - groei - voeropname - visteelt - aquacultuur - dierenwelzijn - dierlijke productie - kweekvis - palingen - huisvesting, dieren - diergezondheid - ammonia - animal physiology - growth - feed intake - fish culture - aquaculture - animal welfare - animal production - farmed fish - eels - animal housing - animal health
Unlocking resources in savannas: how goats and other mixed feeders overcome the negative effects of tannins
Mkhize, N.R. - \ 2015
University. Promotor(en): Herbert Prins, co-promotor(en): Fred de Boer; Ignas Heitkonig. - Wageningen : Wageningen University - ISBN 9789462574274 - 110
geiten - tanninen - diervoeding - diervoedering - savannen - afgrazen - graasduur - begrazing - dierfysiologie - plantensamenstelling - afrika - goats - tannins - animal nutrition - animal feeding - savannas - browsing - grazing time - grazing - animal physiology - plant composition - africa

Abstract

This thesis contributes insights on how condensed tannins might mediate the interactions between woody plants and large herbivores in the African savannas. Current understanding in this regard is still based on data from short-term laboratory experiments, mostly with confined animals and a few correlative field studies that only explore relationships between tannin concentrations of plants with their intake. Although these experiments are a necessary first step in isolating and characterising the effects of condensed tannins, they oversimplify the complex interactions that occur between wild herbivores or livestock and plants. The challenge for research is to translate the roles of tannins in plant-herbivore interactions from controlled experiments to field conditions. The aims of this research were: to (1) investigate how condensed tannins influence foraging behaviour and growth performance of free-ranging ruminant herbivores, and (2) determine the effects of supplements on use of woody plants and intake rates of condensed tannins by free-ranging herbivores in a semi-arid savanna.

Field experiments were conducted and data collected on free-ranging goats as models for all mixed feeders that share similar characteristics with goats. Condensed tannin exposure levels to goats were experimentally increased in the field by orally dosing 15 goats with 20g condensed tannin powder extracted from a bark of tannin-rich species. To reduce tannin exposure, 15 goats were dosed with 20 g of PEG in an attempt to neutralize tannin effects, and another group of 15 goats was dosed only with water and served as a control group. Feeding behaviour of goats supplemented with a protein-rich source, an energy-rich source were compared with that of goats that were not supplemented.

The results indicated that mixed feeders exposed to high levels of condensed tannins spend more time grazing and less time browsing compared to animals with low tannin exposure. However, the findings did not support expectation for tannins to reduce overall foraging time. Therefore, it was concluded that condensed tannins do not necessarily suppress foraging, but only influence the amount of time animals spend foraging on either herbaceous or woody forage. These findings also supported hypothesis that herbivores forage in ways that minimize their intake rate of condensed tannins. Animals altered their foraging behaviour depending on the treatment groups they were allocated to, and compiled diets that indicated tannin minimization as a goal. Moreover, there was support for the notion that condensed tannins are digestibility reducers. It was clear that free-ranging animals are able to employ their behavioural adaptations to chemical defences in ways that mitigate the negative physiological effects on their presumed ultimate fitness. This thesis presents possible effects of nutrient-tannin/toxin interactions on herbivores in African savannas. In the supplementation experiment, proteins and energy equally increased browse consumption by herbivores, with a concomitant increase in tannin intake rates.

These results were explained in light of the ongoing bush encroachment in the African savannas. The expected increase in the availability of browse will probably impose a selection pressure for herbivores that can better utilise the encroaching woody plants known to be endowed with tannins and other carbon-based secondary metabolites. These results are used to generalise about the herbivore health, herbivore nutritional, and environmental benefits that are possible from managing our rangelands and herbivores in ways that increase utilization of chemically defended plants. For example, increased consumption of tannin-rich forage will not only improve nutrition, but it will also reduce internal parasite burden, and reduce bloating by ruminant herbivores while simultaneously reducing the methane emissions that lead to global warming.

A tale too long for a tail too short? : identification of characteristics in pigs related to tail biting and other oral manipulations directed at conspecifics
Ursinus, W.W. - \ 2014
University. Promotor(en): Bas Kemp, co-promotor(en): Liesbeth Bolhuis; Kees van Reenen. - Wageningen : Wageningen University - ISBN 9789462570023 - 248
varkens - staartbijten - gedragsstoornissen - karakteristieken - bangheid - dierenwelzijn - genetische effecten - groeitempo - omgevingsverrijking - diergedrag - dierfysiologie - pigs - tail biting - behaviour disorders - characteristics - fearfulness - animal welfare - genetic effects - growth rate - environmental enrichment - animal behaviour - animal physiology

Ursinus, W.W. (2014). A tale too long for a tail too short? Identification of

characteristics in pigs related to tail biting and other oral manipulations directed

at conspecifics. PhD thesis, Wageningen University, The Netherlands.

Tail biting in pigs, i.e. the chewing on and biting in tails of conspecifics, is a

multifactorial problem leading to impaired pig welfare and health and economic

losses in pig farming. In many countries tail docking is used as a preventive

measure, but there is increased societal concern about this practice. Therefore,

there is an urgent need to understand, prevent, and reduce tail biting and other

damaging behaviours directed at pen mates. The main aim of this thesis was to

identify biological characteristics of barren and enriched housed pigs that relate

to their tendency to develop these damaging oral manipulative behaviours. Tail

biting started already early in life and pigs that displayed tail biting post-weaning

seemed to stem from litters in which tail biting behaviour was already present. The

onset of tail biting behaviour was different for individual pigs, and many pigs were

not consistently tail biters throughout different phases of life. It was difficult to

predict which pigs would develop tail biting based on their individual behaviour.

Groups of pigs with tail biting problems were, however, more easy to identify by

increased activity, and increased levels of pig and pen-directed oral manipulative

behaviours. Subjecting pigs to an individual behavioural test showed that tail

biters may be more fearful. Fearfulness in pigs appeared related to measures

of the brain and blood serotonergic system. Moreover, measures of the blood

serotonergic system seemed temporarily altered in tail biting pigs mainly during

the phase of life in which they displayed this behaviour. Additionally, (tail) biting

behaviour may be associated with higher (phenotypic and genotypic) production,

such as higher growth. Growth of individual pigs can be affected by the other

pigs in a pen. The heritable effect of one pig on the growth of another group

member is referred to as an indirect genetic effect. Pigs with a relatively negative

indirect genetic effect for growth displayed more biting behaviours, caused more

tail damage and destroyed more of the available jute sacks. The presence of strawbedding

or jute sacks as enrichment materials for rooting and chewing largely

reduced damaging biting behaviours and, consequently, tail damage. Pigs that

still develop tail biting behaviour in an enriched environment likely do so due to

a (temporary) physiological problem, whereas in barren housed pigs the lack of

suitable rooting and chewing material plays a large role. Tail biting behaviour

in pigs thus seems to be caused by a variety of temporary states and more

stable traits that influence their motivation to display foraging and exploratory

behaviours. Therefore, the tale of (tail) biting behaviours in pigs needs a better

understanding of underlying physiological processes. Preventing and reducing

damaging biting behaviours in pigs requires a joint effort of science, industry

and society to optimize housing conditions, feeding, management and breeding

of pigs.

The fearful feather pecker : applying the principles to practice to prevent feather pecking in laying hens
Haas, E.N. de - \ 2014
University. Promotor(en): Bas Kemp; A.G.G. Groothuis, co-promotor(en): Bas Rodenburg; Liesbeth Bolhuis. - Wageningen : Wageningen University - ISBN 9789462570429 - 285
hennen - verenpikken - bangheid - gedragsproblemen - lijnen - hormonale controle - stressreactie - ontogenie - legresultaten - dierenwelzijn - diergedrag - dierfysiologie - hens - feather pecking - fearfulness - behaviour problems - lines - hormonal control - stress response - ontogeny - laying performance - animal welfare - animal behaviour - animal physiology

Billions of laying hens are kept worldwide. Severe feather pecking (SFP) is a behaviour which occurs with a high prevalence on commercial farms. SFP, the pecking and plucking of feathers of another bird, induces pain and stress and can ultimately lead to cannibalism. Moreover, SFP can occur if a bird is unable to cope with fear and stress and is living in an inappropriate environment. SFP thus reduces the welfare of many laying hens worldwide. To prevent SFP it is essential to know the risk factors in its development. To that aim, first, two experimental studies were conducted to gain insight in the principles of SFP, and three on-farm studies were conducted to assess the risk factors of SFP under commercial conditions.

THE PRINCIPLES

Factors which relate to SFP are high fearfulness as young and low levels of brain and peripheral serotonin (5-HT) and brain dopamine (DA). Furthermore, commercial laying hen lines can differ in SFP tendencies and associated traits indicating that SFP has a genetic component. In chapters 2 and 3, fear response as young and adult, and stress response, 5-HT and DA brain levels as adult were

compared in hens of two lines: the low mortality line (LML) selected on low levels of mortality due to cannibalism and individual performance vs. the control line (CL) which was selected on individual performance only. Hens were exposed to an Open Field (OF) test at 5 weeks of age and a Manual Restraint (MR) test at 33 weeks of age. At 33 weeks of age, levels of corticosterone (CORT) post MR and 5-HT and DA levels in four brain areas were determined. Hens of the LML were less fearful at both ages and had lower levels of DA in the arcopallium, a somatomotor area involved in fear and motor control, compared to hens of the CL. In chapter 2, it was also shown that fearful chicks had higher levels of CORT and higher activity levels as adult, compared to non-fearful chicks. Moreover,

presence of fearful animals in the group was related to average CORT levels of their pen members. Fearful hens may induce social instability in a group, and thereby affecting the stress-sensitivity of their group mates. These results indicate that groups differ in levels of fear and stress-sensitivity, and that fearfulness at a young age can lead to stress-sensitivity as adults, which create a risk for development of SFP.

THE PRACTICE

In chapters 4, 5 and 6, the laying hen production chain consisting of parent stock, rearing flocks and laying flocks was studied. Risk factors for SFP could originate from previous parts in the chain. Therefore, in all on-farm studies, measurements of SFP, fearfulness, basal CORT and peripheral 5-HT system were obtained, and related to housing conditions and to previous parts in the chain. Fearfulness was assessed, on a flock level, by distance to a stationary person (SP) test and latency

of bird to approach a novel object (NO). Dekalb White (DW) and ISA brown (ISA) crosses whose pure lines differ in levels of fear, CORT, 5-HT and DA, were compared. First, parent stock (PS) flocks were studied and associations between production performance and measurements of fear, stress and 5-HT were conducted and related to group size conditions (chapter 4). Second, rearing flocks originating from PS flocks were studied throughout the rearing period (chapter 5). High levels of feather damage, CORT and 5-HT in the mothers were related to fearfulness and SFP in their offspring at flock level. Especially, a large flock size and limitation and/or disruption in litter supply affected SFP and levels of fearfulness and 5-HT (chapter 5). Finally, high levels of feather damage during the laying period were related to high SFP rearing, and high fearfulness during rearing and laying (chapter 6). These studies together aimed to determine the risk factors for the development of SFP and the resulting feather damage. The main outcomes of these studies are as follows.

Ø Parent stock flocks

DW flocks were more fearful of an SP and hens had higher levels of feather damage than in ISA flocks. ISA flocks, in turn, were more fearful of the NO and hens had higher 5-HT levels than in DW flocks. A small flock size led to higher feed conversion, mortality levels, and smothering events in ISA but not in DW flocks. These results indicate that DW and ISA PS flocks differ in levels of fear and

feather damage, and respond differently to their social environment. For both crosses, fear of an SP related to high mortality and fear of the NO related to low hen body weight, egg weight, and feed intake. High basal CORT related to low egg weight. High fear and stress levels in PS flocks may, thus, negatively affect (re)production, and thereby potentially negatively influence the developing

embryo.

Ø Rearing flocks

In the DW cross, high CORT, feather damage, and 5-HT of mother hens related to high SFP and fearfulness of their rearing flocks at 1 week of age. At 5 weeks of age, a peak in both gentle feather pecking (GFP) and SFP was recorded, coinciding with a disruption in substrate availability (i.e. a temporal absence of substrate) and a limitation of substrate (i.e. limited amounts of substrate

provided) in some of the farms. Especially, ISA pullets showed higher SFP under substrate limitation and became more fearful under substrate disruption than DW pullets. ISA pullets had higher 5-HT levels than DW pullets. Only in the ISA cross, high 5-HT related to high fearfulness, specifically under substrate disruption. For both crosses, high fearfulness was related to high feather damage. Furthermore, in a level system (floor system where levels are gradually added) higher levels of SFP and feather damage were found compared to an aviary system (a tier-system with cages and litter area). These results highlight that; 1) parental effects exist in the development of fearfulness and SFP, 2) disruption and limitation in substrate availability can lead to high SFP at 5 weeks of age, 3) ISA pullets are more strongly influenced by environmental conditions than DW pullets and 4) a level housing, which coincided with a large group size, increase the risk of SFP and feather damage during rearing.

Ø Laying flocks

In our sample, 49% of the laying flocks had severe damage at 40 weeks of age, compared with 71%, 65% and 53% of the rearing flocks at 15, 10 and 5 weeks of age, respectively. High fear of a SP at rearing and high SFP at 5 weeks of age related to high levels of feather damage at lay. In a floor system and at a large flock size higher levels of feather damage were recorded than in an aviary system and at a small flock size. An adjusted management on the laying farm (i.e. aerated blocks, presence of roosters or a radio playing) reduced levels of feather damage compared to standard management. DW flocks were more fearful of the SP and NO than ISA flocks. This study showed that factors during rearing and laying contributed to feather damage at 40 weeks of age.

With the knowledge from the experimental and on-farm studies in this thesis, an assessment of the risk factors for SFP could be established. Risk factors for SFP are: high fear, stress and feather damage in DW parent stock, high fear of humans, especially for DW hens, litter disruption or limitation during rearing, large group sizes, and a floor or level system.

Effectieve bestrijding van varroa (Tweede, licht gewijzigde druk)
Cornelissen, B. ; Blacquière, T. ; Steen, J.J.M. van der - \ 2013
Wageningen : Plant Research International - 48
apidae - honingbijen - bijenziekten - varroa destructor - dierfysiologie - bijenvirussen - vectorbestrijding - bestrijdingsmethoden - diergezondheid - honey bees - bee diseases - animal physiology - bee viruses - vector control - control methods - animal health
De varroa mijtziekte (Varroa destructor) is de belangrijkste bedreiging van de Europese honingbij. Wintersterfte van honingbijen is in de meeste gevallen toe te schrijven aan deze ziekte. Deze tweede, licht gewijzigde druk biedt informatie over de biologie van varroa, de effecten van varroa op honingbijen en de bestrijding van varroa.
Bodybuilders met schubben (interview met A. Palstra)
Palstra, A.P. - \ 2013
Visionair : het vakblad van sportvisserij Nederland (2013)28. - ISSN 1569-7533 - p. 4 - 7.
vissen - danio rerio - europese zalm - zwemmen - dierfysiologie - weerstand - stress - kweekvis - fishes - atlantic salmon - swimming - animal physiology - resistance - farmed fish
Een getrainde vis is een fitte vis, kan een adagium worden in het visonderzoek. Want vissen die genoeg zwemmen groeien harder, zijn minder stressgevoelig en beter bestand tegen ziekten. Hoe dat precies werkt wordt langzaam duidelijk.
Piglet birth weight and litter uniformity : importance of pre-mating nutritional and metabolic conditions
Wientjes, J.G.M. - \ 2013
University. Promotor(en): Bas Kemp, co-promotor(en): Nicoline Nieuwenhuizen-Soede; Henry van den Brand. - S.l. : s.n. - ISBN 9789461735027 - 238
biggen - zeugen - geboortegewicht - variatie - worpen - metabolisme - insuline - tijd tussen werpen van biggen - voer - samenstelling - varkensvoeding - voedingsfysiologie - diervoeding - dierfysiologie - piglets - sows - birth weight - variation - litters - metabolism - insulin - farrowing interval - feeds - composition - pig feeding - nutrition physiology - animal nutrition - animal physiology

High piglet birth weights and litter uniformity are important for piglet survival and piglet performance. Within-litter variation in piglet birth weight is the consequence of within-litter variation in early embryo development, which in turn reflects variation in follicle and oocyte development. Insulin-stimulating diets before mating can influence litter development and uniformity, probably through beneficial effects of insulin on IGF-1 and follicle development. The first aim of this thesis, therefore, was to study effects of insulin-stimulating diets during the weaning-to-estrus interval (WEI) on plasma insulin and IGF-1 levels and follicle development, and consequences for embryo, fetal and placental development and uniformity at different stages of pregnancy in sows. Results of this thesis show that plasma insulin levels during WEI can be effectively enhanced by dietary sugars as dextrose and sucrose (high peaks directly after feeding) and starch (enhanced insulin levels at ~4h after feeding) in a dose-dependent manner. Follicle development and subsequent litter uniformity of embryos (at day 10 of pregnancy) or fetuses and placentas (at day 42 of pregnancy), however, were not affected by insulin-stimulating diets during WEI, nor related to plasma insulin and IGF-1 levels during WEI. Besides effects of pre-mating diets, plasma insulin and IGF-1 levels and follicle development are also influenced by the pre-mating metabolic state of the sow: in sows with severe body condition loss during lactation, plasma insulin and IGF-1 levels and follicle development at weaning are suppressed, and restoration of plasma insulin and IGF-1 levels and follicle development occurs in sows with a prolonged lactation or a prolonged weaning-to-pregnancy interval (WPI). The second aim of this thesis, therefore, was to study effects of these pre-mating conditions related to sow metabolic state on subsequent piglet birth weight and litter uniformity. In this thesis it is shown for the first time that pre-mating conditions related to sow metabolic state affect subsequent litter uniformity. Litter uniformity at birth was compromised by severe sow body condition loss during previous lactation and improved in sows with a prolonged WPI. Furthermore, it was shown that in (organic) sows with prolonged lactations (6 weeks) and large litters (17.4±0.3 piglets), insulin-stimulating diets before mating did not result in improved piglet birth weights or litter uniformity. This may be related to a restored follicle development at weaning in these sows. In these large organic litters, piglet birth weight and litter uniformity were strongly related to piglet survival during lactation. To conclude, results of this thesis confirm that litter uniformity at birth is already (partly) determined during the pre-mating period, likely related to (insufficient) restoration of follicle development. In contrast to previous studies, insulin-stimulating diets during WEI did not improve litter uniformity of embryos, fetuses or placentas and/or piglets in sows. The role of plasma IGF-1 levels and follicle development at weaning (both related to sow parity and sow body condition loss), and effects of insulin-stimulating diets during lactation, need further study. Finally, although effects of pre-mating nutritional and metabolic conditions on subsequent piglet birth weight and litter uniformity seem only marginal, these marginal effects can have substantial effects on pre-weaning piglet survival.

Swimming Physiology of Fish: Towards Using Exercise to Farm a Fit Fish in Sustainable Aquaculture
Palstra, A.P. ; Planas, J.V. - \ 2013
Heidelberg [etc.] : Springer - ISBN 9783642310485 - 429
dierfysiologie - vissen - wildbeheer - zwemmen - genomica - diergenetica - gedragswetenschappen - ontogenie - aquacultuur - animal physiology - fishes - wildlife management - swimming - genomics - animal genetics - behavioural sciences - ontogeny - aquaculture
(Zelf) meten aan de vitaliteit van bijen
Steen, J.J.M. van der - \ 2012
Bijenhouden 8 (2012)6. - ISSN 1877-9786 - p. 6 - 8.
apidae - honingbijen - wilde bijenvolken - stuifmeel - diergezondheid - meting - broedsel - dierfysiologie - onderzoek - honey bees - wild honey bee colonies - pollen - animal health - measurement - hatch - animal physiology - research
Tijdens het symposium van bijen@wur PRI op 18 maart vertelde Sjef van der Steen over zijn onderzoek in 2009 en 2010 naar invloed van variatie en continuïteit in de aanvoer van stuifmeel op de vitaliteit van bijenvolken. Voor Bijenhouden schreef hij een artikel over zijn aanpak en de uitkomsten, met tot slot advies voor de imker.
Transport conditions of fattening pigs from farm to slaughterhouse : transport of pigs for more than 8 hours at two space allowances
Gerritzen, M.A. ; Marahrens, M.A. ; Steinkamp, K. ; Reimert, H.G.M. ; Werf, J.T.N. van der; Hindle, V.A. - \ 2012
Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 605) - 42
dierenwelzijn - varkens - varkenshouderij - transport - veevervoer - diergedrag - dierfysiologie - animal welfare - pigs - pig farming - transport of animals - animal behaviour - animal physiology
An investigation of travelling conditions of slaughter pigs during 8 long (>8h) journeys across Germany. Animals were transported at two loading densities. Observations of physiological (heart activity, blood parameters, body temperature) and behavioural responses (posture, fighting) weremade together with registration of environmental aspects (including indoor and outdoor temperature, wind speed, humidity, weather conditions). Driving conditions were also registered.
Effects of hatching time and hatching system on broiler chick development
Ven, L.J.F. van de - \ 2012
University. Promotor(en): Bas Kemp; Peter Groot Koerkamp, co-promotor(en): Henry van den Brand; A.V. van Wagenberg. - S.l. : s.n. - ISBN 9789461734471 - 173
vleeskuikens - kuikens - kunstmatig bebroeden - broedmachines - postnatale ontwikkeling - broedfactoren - broedinstallaties - dierfysiologie - groei - voedering - pluimveehouderij - broilers - chicks - artificial hatching - brooders - postnatal development - hatching factors - hatcheries - animal physiology - growth - feeding - poultry farming

Key words: hatching time, hatching system, chick physiology, broiler growth, chick quality.

Chicks hatch over a time window of 24-36 hours and are only removed from the hatcher when the majority of the chicks have hatched. Especially for the early hatching chicks this leads to delays in the first feed and water access and consequently negative effects on chick development. In an alternative hatching system, named Patio, the hatching and brooding phase are combined, thereby enabling direct posthatch feed and water access. Environmental conditions in Patio differ from those in hatchers, which may further influence chick quality, physiology, and growth. Chicks hatching at different moments may respond differently to these different conditions in both hatching systems. In this thesis, the first aim was to determine effects of hatching in the Patio system on hatchability, chick quality, and growth. The second aim was to determine the physiological status of chicks of different hatching moments, in the hatcher and the Patio system, at hatch, and at chick collection (21.5 d of incubation). Effects of hatching time and moment of first feed and water access on posthatch growth were also included.

Hatchability of fertile eggs was 1.03% higher in the Patio system compared to the hatcher, which was probably due to different climate conditions during the hatching phase. At hatching, chick physiology was not clearly affected by hatching system, but effects of moment of hatching in the hatch window were clear: longer incubation times led to increased organ weights and decreased yolk weights, suggesting a higher level of maturation in late hatching chicks. At the moment of chick collection, Patio chicks, having immediate feed and water access,showed larger body and organ weights, higher hepatic glycogen reserves, higher plasma glucose and T3 levels, and lower corticosterone levels compared to hatcher chicks which were fasted between hatching and chick collection. Usinga chick qualitative score based on physical traits and the incidence of second grade chicks, chick quality was lower in Patio than in hatcher chicks. However the quality scores used were not predictive for posthatch performance. Patio chicks showed improved posthatch growth compared to hatcher chicks, which was not related to different climate conditions during hatching, but to earlier feed and water access. Apart from higher growth from d0-7 in early and midterm vs late hatching chicks, effects of hatching time on growth were not clear from this thesis.

In conclusion, despite considerable differences in climate and other environmental factors, effects of hatching system on physiology of broiler chickens at hatch and growth performance up to slaughter age are limited. Perinatal chick physiology is affected by the moment of hatching in the hatch window, and by posthatch conditions in the hatching system, especially early feed and water access.

A physiologically based kinetic model for the prediction of plasma cholesterol concentrations in mice and man
Pas, N. van de - \ 2011
University. Promotor(en): Ivonne Rietjens; Ruud Woutersen, co-promotor(en): A.A. de Graaf. - [S.l.] : S.n. - ISBN 9789461731258
cholesterolmetabolisme - klaring (plasma) - dierfysiologie - mannen - cholesterol metabolism - clearance - animal physiology - men

An increased plasma cholesterol concentration is associated with increased risk of cardiovascular disease. However, individuals vary largely in their response to cholesterol lowering drugs and 40% of them, do not reach their cholesterol-lowering target. Development of novel therapies, for example combinations of existing drugs, can be accelerated by more mechanistic understanding of cholesterol metabolism. This understanding can be improved using computational models.

This thesis describes the development, validation, and analysis of a physiologically based kinetic (PBK) model for the prediction of plasma cholesterol concentrations in humans. For this purpose, first a PBK model for the mouse was set up, calibrated and validated, using ensemble modeling. Then the mouse model was converted to a model for humans. It describes the 21 most influential physiological reactions affecting cholesterol concentrations in 8 pools, including liver, HDL, and non-HDL. The model was parameterized using literature data and validated using clinical data for human mutations and drug interventions, taken from literature.

The model was applied to find properties that determine the individual response to drugs. The processes: hepatic cholesterol synthesis, peripheral cholesterol synthesis, and hepatic cholesterol esterification were major determinants of the non-HDL-C response to the cholesterol-lowering drug pravastatin.

We conclude that plasma cholesterol concentrations and effects of genetic polymorphisms and drugs thereupon can be predicted in silico and thatPBK modeling can provide novel mechanistic insights.

Post weaning altrenogest use in sows: follicle growth, endocrine profiles and subsequent fertility
Leeuwen, J.J.J. van - \ 2011
University. Promotor(en): Bas Kemp, co-promotor(en): Nicoline Nieuwenhuizen-Soede. - [s.l.] : S.n. - ISBN 9789085859963 - 144
zeugen - synthetische progestogenen - spenen - voortplantingsvermogen - eierstokfollikels - rijpen - endocrinologie - vruchtbaarheid - dierfysiologie - dierlijke productie - varkenshouderij - sows - synthetic progestogens - weaning - reproductive performance - ovarian follicles - maturation - endocrinology - fertility - animal physiology - animal production - pig farming

A severe negative energy balance during first lactation may result in poor reproductive performance in the second litter. Allowing the sow recovery time after weaning by inseminating the sow the second estrus after weaning (skip a heat) improves reproductive performance. Postponing estrus for a shorter period after weaning using daily altrenogest administration has also been found to influence reproductive performance. The aim of this thesis was to develop a better understanding of consequences of altrenogest after weaning for follicle development and subsequent reproductive performance. Therefore, a first experiment investigated follicle development during and after post weaning altrenogest treatments and related this to subsequent fertility. It showed that follicle size increased during altrenogest treatment (independent of dose and duration), but no effects were found on fertility parameters on day 5 of gestation. Therefore, a second experiment studiedthe effect of duration of treatment on follicle development and subsequent farrowing rate and litter size. This experiment showed again an increase in follicle size and also showed that long altrenogest treatments (15 d) improve fertility, but that shorter treatments (8 d) reduce farrowing rates in sows with large follicles at weaning. So, to prevent outgrowth of follicles before weaning a third experiment started altrenogest treatment 3 d before weaning. This did not suppress follicle growth, but fertility was improved after altrenogest treatment in primiparous sows with compromised body condition at weaning. A fourth experiment attempted to stimulate follicle growth before weaning using split-weaning (reducing litter size to the 6 smallest piglets 3 d before complete weaning) and found that split-weaning resulted in lower embryonic survival, especially in sows with large follicles at weaning or high follicle growth during treatment. Because in all experiments sows showed follicle growth during altrenogest treatment, it was suspected that LH release was not completely suppressed during altrenogest treatment. Therefore, a fifth experiment investigated LH pulsatility during the last day of altrenogest treatment and indeed showed that LH release was suppressed during only a part of the 24 h between altrenogest administrations. Finally a last experiment showed a release pattern of both FSH and estradiol that varied over the day related with the moment of daily altrenogest administration. Further, a decrease of estrogenic activity was found during the second week of post weaning altrenogest treatment, probably as a result of reduced LH responsiveness. The level of estrogenic activity was related to weight loss during lactation. Therefore, it is assumed that LH and FSH release during altrenogest treatment stimulate follicle growth, but that levels are not high enough to sustain outgrowth of the follicles to pre-ovulatory sizes and, as a result, follicles go into atresia after on average 5-8 d of treatment. This may explain why long altrenogest treatments (12-15 d) result in improved fertility, short altrenogest treatments (3-4 d) have little effect on fertility and intermediate altrenogest treatments (5-8 d) may reduce fertility. As there is large variation between sows (parity, lactational burden, follicle size), this may also affect their response to altrenogest treatment. In general, to improve reproductive performance, it is recommended to start altrenogest treatment 3-6 h before weaning and to apply intermediate treatments (5-8 d) only in primiparous sows that suffered a severe lactational burden and are in low body condition at weaning.

Perinatal development and nutrient utilization in chickens : effects of incubation conditions
Molenaar, R. - \ 2010
University. Promotor(en): Bas Kemp, co-promotor(en): Henry van den Brand; R. Meijerhof. - S.l. : s.n. - ISBN 9789085858188 - 165
vleeskuikens - eieren - embryonale ontwikkeling - embryologie - broeden - voedingsfysiologie - vleeskuikenresultaten - dierfysiologie - broilers - eggs - embryonic development - embryology - incubation - nutrition physiology - broiler performance - animal physiology
Suboptimal incubation conditions can negatively affect survival and development of chicken embryos. However, physiological mechanisms that may explain these effects, and the long-lasting consequences are largely unknown. Therefore, the first aim of this thesis was to investigate effects of eggshell temperature (EST) and O2 availability during incubation on survival, development, physiology, and nutrient utilization of chicken embryos. The second aim was to investigate long-lasting effects of suboptimal EST on survival and subsequent performance of broiler chickens. The first study investigated effects of a high (38.9°C) or a normal (37.8°C) EST combined with a low (17%), normal (21%), or high (25%) O2 concentration from day 7 until 19 of incubation on the survival rate, nutrient utilization, and the developmental and physiological status of broiler embryos. The second study investigated effects of high EST on glucose metabolism in broiler embryos using [U-13C]glucose. The third study investigated effects of high EST on growth performance and the incidence of ascites in broiler chickens. Finally, effects of a high EST and a hole in the air cell on the developmental and physiological status of layer hatchlings were investigated. Results showed that a high EST or low O2 availability from the first week of incubation onward negatively affected survival and development of broiler chickens from their perinatal period until slaughter age. Body development of broiler hatchlings was reduced after high EST incubation because of a lower efficiency in protein utilization for growth. This was possibly due to the use of glucogenic amino acids as a glucogenic energy source, because high EST increased the glucose oxidation in broiler embryos during the second half of incubation and resulted in lower hepatic glycogen. Body development was proportional to the O2 availability during incubation. In addition, differences in O2 concentration during incubation seem to affect the development of adaptive mechanisms, and these mechanisms might possible influence nutrient utilization and body development. High EST in the last week of incubation in layer embryos negatively affected hatchling development, but the effect of a hole in the air cell was minimal. Effects of high EST were long-lasting in broiler chickens expressed by a lower body weight and a higher ascites incidence during the growout period. In conclusion, negative effects of suboptimal incubation conditions can be partly explained by changes in nutrient utilization and metabolite levels in the perinatal period and can have long-lasting effects on the survival and performance of broiler chickens.
Effectieve bestrijding van varroa
Cornelissen, B. ; Blacquiere, T. ; Steen, J.J.M. van der - \ 2010
Wageningen : Plant Research International - 48
apidae - honingbijen - varroa destructor - bijenziekten - dierfysiologie - bijenvirussen - vectorbestrijding - bestrijdingsmethoden - diergezondheid - honey bees - bee diseases - animal physiology - bee viruses - vector control - control methods - animal health
De varroa mijtziekte (Varroa destructor) is de belangrijkste bedreiging van de Europese honingbij. Wintersterfte van honingbijen is in de meeste gevallen toe te schrijven aan deze ziekte. Deze brochure van de WUR biedt informatie over de biologie van varroa, de effecten van varroa op honingbijen en de bestrijding van varroa.
Storage of Hatching Eggs : Effects of storage and early incubation conditions on egg characteristics, embryonic development, hatchability, and chicken quality
Reijrink, I.A.M. - \ 2010
University. Promotor(en): Bas Kemp, co-promotor(en): Henry van den Brand; R. Meijerhof. - [S.l. : S.n. - ISBN 9789085856658 - 164
eieren - opslag - broeden - ei-uitkomstpercentage - embryonale ontwikkeling - ei-albumen - eikwaliteit - kuikens - pluimveehouderij - dierfysiologie - eggs - storage - incubation - egg hatchability - embryonic development - egg albumen - egg quality - chicks - poultry farming - animal physiology
Key words: egg storage, embryonic development, albumen quality, hatchability, chick quality

It is well known that an increase in the storage duration increases incubation duration and decreases hatchability and chick quality. The negative effects of prolonged egg storage (> 7 days) may be caused by changes in the embryo, in the egg characteristics, or by both. The first aim of the current thesis was to investigate which physiological mechanisms are involved in the negative effects of prolonged egg storage on hatchability and chick quality. The second aim was to investigate how these negative effects of prolonged egg storage can be reduced by making changes in storage or early incubation conditions. Treatments, such as prestorage incubation, frequent warming during storage, a change in the storage air composition, different preincubation warming profiles, and hypercapnic incubation during the first 5 days of incubation were used in the current thesis to gain more insight in the cause of the negative effects of prolonged egg storage. Prestorage incubation and frequent warming during storage increased the stage of embryonic development and the number of viable embryonic cells. The effect of these treatments on hatchability was nihil, positive or negative and seems to depend on the stage of embryonic development before and after the treatment. The storage air compositions, studied in the current thesis did not affect embryonic development, hatchability, or chick quality, when eggs were stored for 14 days. This suggests that changes in albumen quality during storage do not affect hatchability and chick quality. The 24-h preincubation warming profile decreased embryonic mortality during the first 9 days of incubation in comparison with the 4-h preincubation warming profile when eggs were stored for 13 days. Hypercapnic incubation during the first 5 days of incubation decreased albumen pH during early incubation, but did not improve hatchability. In conclusion, embryo characteristics seem to have a more important role in the negative effects of prolonged egg storage than changes in the egg characteristics, such as changes in the albumen pH and albumen height.

Het effect van verhoogde ammonia concentratie in het water op fysiologie, groei en voeropname van Afrikaanse meerval (Clarias gariepinus)
Schram, E. ; Roques, J. ; Abbink, W. ; Spanings, T. ; Vries, P. de; Bierman, S.M. ; Vis, J.W. van de; Flik, G. - \ 2010
IJmuiden : IMARES (Rapport / IMARES Wageningen UR C026/10) - 29
aquacultuur - clarias gariepinus - ammoniak - nadelige gevolgen - effecten - dierfysiologie - voeropname - dierenwelzijn - aquaculture - ammonia - adverse effects - effects - animal physiology - feed intake - animal welfare
IMARES onderzocht het effect van de ammoniaconcentratie in het kweekwater op groei, voeropname en fysiologie van Afrikaanse meerval (Clarias gariepinus). Het doel van dit onderzoek was het vaststellen van de maximale ammoniaconcentratie (grenswaarde) waarbij geen negatieve effecten op welzijn van de vis en de productie waar te nemen zijn.
The influence of light and water flow on the growth and physiology of the scleractinian coral Galaxea fascicularis
Schutter, M. - \ 2010
University. Promotor(en): Johan Verreth; Rene Wijffels, co-promotor(en): Ronald Osinga. - [S.l. : S.n. - ISBN 9789085855354 - 230
koralen - cnidaria - lichtsterkte - waterstroming - groei - metabolisme - dierfysiologie - aquariums - aquacultuur - corals - light intensity - water flow - growth - metabolism - animal physiology - aquaria - aquaculture
Background
Zooxanthellate scleractinian corals are sessile colonial animals that live in symbiosis with photosynthetic algae, the zooxanthellae. They can feed both phototrophically and heterotrophically and produce an external skeleton of calcium carbonate, which process is enhanced by light. They are the key organisms of tropical coral reefs and responsible for building the large carbonate structures. Tropical coral reefs are increasingly threatened by both natural and anthropogenic stresses. Concurrently with the gradual decline of coral reefs, a growing interest in keeping this delicate ecosystem in aquaria has emerged. To reduce harvest from the wild, increasing effort is put in developing cost-effective coral aquaculture culture. The objective of this thesis was to study the influence of light (irradiance and photoperiod) and flow on coral growth and physiology. Furthermore, the interaction between light and water flow was studied.

Methods
The effect of flow (Chapter 2), light (Chapter 3), photoperiod (Chapter 4) and the interaction between light and flow (Chapter 5) on coral growth were studied in long-term experiments monitoring several growth parameters such as buoyant weight (i.e. skeletal mass), surface area and polyp number. Physiological parameters such as photosynthesis and respiration were measured in respirometric flowcells to provide an explanation for the observed differences in growth. Moreover, an overview was given of different factors controlling coral growth and how such knowledge can be translated to aquaculture practice (Chapter 6).

Results
In the absence of water flow, coral growth was significantly lower and corals appeared unhealthy. In the presence of water flow (10, 20 and 25 cm s-1, at 90 µE m-2 s-1), growth rates were significantly increased. However, growth was not significantly different between 10 cm s-1 and 20 cm s-1, but again significantly increased at 25 cm s-1. Differences in growth could not be explained by net photosynthetic rate and Scope for Growth based on phototrophic carbon, since these parameters decreased with increasing water flow (Chapter 2). Increasing irradiance significantly increased the specific exponential growth rate of Galaxea fascicularis. The relation between skeletal growth and net photosynthesis was not directly proportional, but distorted at high irradiance levels (Chapter 3). Increasing photoperiod did not increase the specific exponential growth rate of Galaxea fascicularis. However, since growth neither increased with increasing irradiance, it is suggested that growth was limited by another factor and light was therefore saturating. The corals in the 24 hour light treatment were not able to adapt to prolonged light duration. However, the corals in the 16 hour light treatment probably photo-acclimated to prolonged photoperiod under light-saturating conditions by reducing their hourly photosynthetic rates (16 hour vs. 8 hour light) As a result, daily net photosynthetic was not significantly different, just as their growth rates (Chapter 4). The interaction between light and water flow for coral growth was significant. Water flow stimulated coral growth more at 600 µE m-2 s-1 than at 300 µE m-2 s-1 and the highest growth rates were attained at high irradiance (600 µE m-2 s-1) in combination with high flow rates (15-25 cm s-1). Nevertheless, enhancement of coral growth with either increasing irradiance or increasing water flow could not be explained by net photosynthetic rates (Chapter 5). There are many factors (both environmental and genetical) that can potentially limit or inhibit coral growth. Optimization of coral aquaculture therefore requires close fine-tuning of factors. Growth models can be used as a tool to determine the best culture strategy (Chapter 6).

Conclusion
Increasing water flow has a positive effect on coral growth at a wide range of irradiance levels (90, 300 and 600 µE/m2/s). Increasing irradiance also has a positive effect on coral growth. However, the positive relation between irradiance and coral growth is disturbed when other factors are limiting. Corals were able to retain their growth rates upon photoperiod extension under light-saturating conditions, presumably by means of reducing their hourly photosynthetic rate. At high irradiance levels, the enhancement of coral growth was not proportionally related to net photosynthesis, suggesting that other factors become limiting. Since the interaction between irradiance and water flow is significant, this indicates that water flow can remove some of those limitations at high irradiance levels. The mechanism of enhancement did not seem related to differences in net photosynthetic rate, but is possibly related to reduced energy allocation toward costly photo-protective mechanisms at high irradiance and high flow.
The information in this thesis should not be used as a blueprint for coral aquaculture, however, its value lies in providing a blueprint for targeted optimization studies of coral aquaculture. Since the magnitude of effect of one factor often depends on the other, it is of importance for the future to perform multi-factorial experiments to provide insight in the interactions between factors.




Under light-saturating conditions, further increases in irradiance or extension of photoperiod do not result in more growth. [


Increasing irradiance has a positive relation with both coral growth and net photosynthesis. At high irradiance levels, the enhancement of coral growth was not proportionally related to net photosynthesis, suggesting that other factors become limiting. Since the interaction between irradiance and water flow is significant, this indicates that water flow can remove some of those limitations at high irradiance levels. The mechanism did not seem related to differences in net photosynthetic rate, but is possibly related to reduced energy allocation toward costly photo-protective mechanisms at high irradiance and high flow.
Under light-saturating conditions, further increases in irradiance or extension of photoperiod do not result in more growth. [


Both increasing irradiance and water flow enhance coral growth. Enhancement of coral growth by light was not proportionally related to net photosynthesis at higher irradiance levels, suggesting that other factors become limiting. Since the interaction between irradiance and water flow is significant, this indicates that water flow can remove some of those limitations at high irradiance levels. The mechanism did not seem related to differences in net photosynthetic rate, but is possibly related to reduced energy allocation toward costly photo-protective mechanisms at high irradiance and high flow.
Under light-saturating conditions, further increases in irradiance or extension of photoperiod do not result in more growth. [


Increasing water flow has a positive effect on coral growth at a wide range of irradiance levels (90, 300 and 600 µE/m2/s). In our studies, differences in growth could not be explained with differences in net photosynthetic rate. Rather differences in growth could be related to algal competition and sedimentation or other physiological parameters such as (in)organic nutrient uptake, relief of photo-oxidative stress and dark respiration that are influenced by water flow.
Increasing irradiance also has a positive effect on coral growth. Enhancement of coral growth by light was not proportionally related to net photosynthesis at higher irradiance levels, suggesting that other factors become limiting. The significant interaction between light and water flow indicates that water flow can remove some limitations and that the presence of water flow is very important for optimal light use for coral growth. The mechanism did not seem related to differences in net photosynthetic rate, but is possibly related to reduced energy allocation toward costly photo-protective mechanisms at high irradiance and high flow.
The effect of increasing photoperiod under light-limiting conditions still needs to be established.



Since enhancement of coral growth did not seem to be d… by photosynthesis at higher irradiance levels [WEL, maar niet proportional], it suggested limited.. One of such factors that can remove limitations is water flow. A significant interaction between light and water flow is detected, …
but this effect is dependent on water flow.
The interaction between light and water flow indicates that water flow is very important for optimal light use for coral growth. The mechanism is still unclear, but is possibly related to reduced energy allocation toward costly photo-protective mechanisms at high irradiance and high flow.


Both increasing irradiance and water flow have a positive effect on coral growth, and a significant interaction is found between light and water flow.

The positive effect of increasing water flow on coral growth was found to be significant both at an irradiance of 90 µE/m2/s (Chapter 2), 300 µE/m2/s and 600 µE/m2/s (Chapter 5). Neither of these differences in growth were supported by a significant increase in net photosynthetic rate, in contrast to our expectations. The positive effect of increasing water flow on coral growth is probably a consequence of both external (algal competition and sedimentation) and internal mechanisms( (in)organic nutrient uptake, relief of photo-oxidative stress, respiration). Different at different irradiance levels. External at 90, internal at 300 and 600
The positive effect of irradiance on skeletal growth was demonstrated in both Chapter 3 and 5. The relationship with photosynthesis irradiance curve not proportional.

- mediation by P not clear.
- The relation between skeletal growth and net photosynthesis was not proportional,

In contrast, no positive effect of irradiance on skeletal growth was found in Chapter 4.
Both specific growth rate and net photosynthesis increased with irradiance, however, this relationship was not proportional.
It is suggested that .at high irradiance levels, skeletal growth (i.e. calcification and organic matrix synthesis) is not limited by light or photosynthesis. At high irradiance, other factor (e.g. availability of bicarbonate (i.e. aragonite saturation state), heterotrophic feeding and/or water flow) may become limiting.

Water flow and light…
Photoperiod… still needs to be established. .. offset limitations . optimize balance between factors






At an irradiance of 90 µE m-2 s-1, water flow enhanced coral growth
Increased water flow enhanced coral growth at a wide range of irradiances: 90 µE m-2 s-1 (Chapter 2), 300 and 600 µE m-2 s-1 (Chapter 5). AT 90 µE m-2 s-1, no The mechanism of enhancement is however not clear.

Flow enhanced growth.. absence of flow detrimental.. did… however.. P, algae..
Light… relation growth and photosynthesis distorted.. light enhanced calcificcaiotn.
Photoperiod… no effect .. light not limiting.. photoacclimation.. 24 not able to adapt, but 16 hours well, probably by reducing hourly P.

Light x flow…

Interaction between light and water flow (chapter 5)..
… no diff chapter 4… Review factors (chapter 6)
.. examined… chapter.. Furthermore… In addition..

different mechanisms at different irradiance levels. No relation with P. At 90… reduce disturbance of coral growth by competing algae. at 300 and 600 …. Reduce photo-protective mechanisms

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