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Source-oriented strategies to mitigate ammonia emission from broiler production
No full textGlobally, broiler production is an important source of animal protein. However, intensive broiler production contributes to ammonia emissions and the associated harmful effects on the environment and human health. Ammonia is the main gaseous pollutant from broiler production. Several regulations and policies have been developed (and are adapted) in order to reverse its adverse impacts. Therefore, mitigation strategies are needed to reduce ammonia emissions from broiler production facilities. Preference should be given to source-oriented strategies as they also improve the indoor air quality which is beneficial to the well-being of the farmer and the animals. Currently, farmers lack affordable, efficient techniques to reduce the production and emission of ammonia in the short term.
Therefore, the aim of this PhD research was to investigate how source-oriented nutritional (such as a reduction in crude protein intake, phase feeding, and feed form) and management (different bedding materials) strategies influence litter quality and ammonia volatilization from broiler litter. Furthermore, because the obtained results did not lead to unequivocal conclusions, a more fundamental study was set up in which it was investigated whether certain litter parameters (such as litter moisture, caking, or friability) dominated towards ammonia volatilization from the litter. The effect of the strategies on other important parameters such as broiler performance, meat yield and quality, as well as foot- and hock lesions were also evaluated.
In the general introduction, the processes involved in the production and volatilization of ammonia in broiler litter, as well as influencing factors are explained. Methods and techniques to measure ammonia are briefly discussed. This chapter also gives an overview of the impact of ammonia emissions on the environment, human and animal health, as well as the regulations and policies regarding ammonia emission reduction in Europe. Finally, mitigation strategies (end-of-pipe and source-oriented) for ammonia emissions, with a focus on broiler production, are discussed.
According to the literature, a reduction in dietary crude protein content while maintaining amino acid requirements reduces nitrogen excretion in broilers. A reduction in dietary crude protein has several advantages: litter quality is improved, it positively influences bird welfare parameters such as the incidence of foot lesions, and leads to a reduction in ammonia. Therefore, a study was set up to assess the effect of feed form (mash and pellets) and a reduction in dietary crude protein (while maintaining digestible amino acid to lysine ratios) on ammonia concentrations, litter composition and quality, and nitrogen utilization. Furthermore, broiler performance, meat yield and quality, as well as foot- and hock lesions were evaluated. Broilers were fed diets in pellet and mash form with crude protein levels of 205 g/kg (high), 187.5 g/kg (intermediate), and 175 g/kg (low) in the grower phase and 195 g/kg (high), 180 g/kg (intermediate), and 165.6 g/kg (low) in the finisher phase. It was found that, with the supplementation of essential amino acids, dietary crude protein can be decreased to 187.5 g/kg and 180 g/kg in the grower and finisher phases respectively without, impairing performance, meat yield and quality. A further reduction to 165.6 g/kg in the finisher phase reduced growth performance. A reduction in dietary crude protein significantly reduced ammonia concentrations at litter level at 5 and 6 weeks of age. When comparing the feed form, litter quality was better for mash treatments than pellet treatments, and broilers fed mash diets had a lower incidence of foot- and hock lesions than broilers fed pellets. However, mash diets could not maintain similar performance and slaughter yield to pellets. The ammonia concentrations at litter level tended to be lower for pellets at 5 weeks of age, possible due to the worse litter quality of pellets.
Another nutritional strategy studied in this thesis was reducing the crude protein intake of broilers by feeding more phases to closer meet the nutritional needs of the birds. In this study, the effect of a 3- and 5-phase feeding program was compared by evaluating the same parameters as determined in the previously described experiment. The 3-phase diets were formulated to crude protein and digestible lysine contents of 205 g/kg and 11.5 g/kg (0 to 9 days of age), 195 g/kg and 10.8 g/kg (9 to 24 days of age), and 183.3 g/kg and 10.15 g/kg (24 to 39 days of age), respectively. The 5-phase diets had additional phases from 17 to 24 days of age (187.8 and 10.4 g/kg) and from 32 to 39 days of age (177 and 9.8 g/kg). Significantly lower ammonia concentrations were measured at litter level for the 5-phase treatment than the 3-phase treatment at 23 and 37 days of age. At 24 and 32 days of age, the litter pH was significantly lower for the 5-phase treatment compared to the 3-phase treatment. The lower ammonia concentrations for the 5-phase treatment also coincided with numerically lower litter total ammoniacal nitrogen concentrations at 24 and 39 days of age as well as numerically lower litter nitrogen concentrations at 39 days of age. Broilers from the 5-phase treatment had a lower incidence of foot lesions at 24 days of age. Between 17 and 24 days of age as well as for the overall period, the feed efficiency of broilers fed 5 phases was significantly reduced. Despite no significant differences for nitrogen retention and excretion parameters, there was an indication of birds from the 5-phase treatment to have a higher nitrogen retention and lower nitrogen excretion, while maintaining performance and meat yield, although feed efficiency was slightly reduced. The absence of significant differences between the treatments in this study may be due to the fact that the crude protein and digestible amino acid levels were based on crude protein levels applied in practice in the EU, which are lower than NRC (1994) and breed (Aviagen, 2019) recommendations. The results from these studies are promising as there is a possibility of lowering dietary crude protein intake content by reducing the crude protein content of the feed or by means of feeding more phases. The positive effects of a dietary crude protein reduction described in the literature, such as improved litter quality, decreased incidence of foot lesions, and lower nitrogen excretion were confirmed. Furthermore, the lower ammonia volatilization from the litter may lead to lower ammonia emissions from commercial broiler facilities, which has several environmental advantages.
In addition to nutritional strategies, management strategies to mitigate ammonia were also studied in this thesis. Different types of bedding materials will have different physical and chemical properties that will affect the litter quality and ammonia volatilization throughout the rearing period. Therefore, the effect of different bedding materials on ammonia volatilization and litter quality was studied. Six bedding materials were compared: wood shavings, flax, peat, corn silage, chopped wheat straw, and broken flax pellets. Choice of bedding materials was based on what is commonly used in Europe. The ammonia concentrations at litter level did not differ significantly between the different bedding materials at 30 and 36 days of age. At 30 days of age, the flax, peat, corn silage, and broken flax pellets treatments numerically had the lowest ammonia concentrations. At 36 days of age, numerically the highest ammonia concentrations were measured for the peat and chopped wheat straw treatments. Chopped wheat straw, wood shavings, and flax had the worst litter quality and the highest incidence of foot lesions at the end of the rearing period. For the total period, highest feed intake and body weight was obtained if broilers were housed on peat. The bedding materials such as flax, peat, corn silage, and broken flax pellets have the potential to reduce ammonia volatilization from the litter earlier in the rearing period (up to about 30 days of age). After that, the accumulation of excreta in the litter may outweigh the unique properties (natural acidity, friability, water absorption and ammonia adsorption capacities) of the individual bedding materials, which probably caused the increase in ammonia measured at 36 days of age. The studied bedding materials may each require specific preparation and individual management to optimise broiler performance and to mitigate risks of the development of foot lesions and ammonia release from the litter. For example, bedding materials such as wood shavings, wheat straw, and flax, which tend to compact relatively easy when moisture content increases may be regularly turned or de-caked to improve friability. However, such practices may lead to surges in ammonia emissions. Another approach may be to mix such bedding materials with peat or corn silage which maintain their friability well. In the case of peat and corn silage, it may be beneficial to apply a higher amount of bedding material at the beginning of the rearing period. This may reduce the diluting effect caused by excreta accumulation in the litter, and the naturally low pH may be better preserved. Considering all parameters measured in this experiment, corn silage and broken flax pellets performed quite well, however, more research is needed to find a more suitable bedding material which is beneficial to the environment as well as the welfare of broilers.
To study the effect of litter friability and compaction of the litter layer as well as litter moisture content on ammonia volatilization an experiment was set up where the litter was regularly raked or left undisturbed, and the moisture content was artificially increased by means of regularly spraying water over the litter surface. In total, 6 treatments were studied: NR(0) = no raking of the litter, no water added; R(0) = raking of the litter, no water added; NR(1.5) = no raking of the litter, 1.5 L of water added; R(1.5) = raking of the litter, 1.5 L of water added; NR(3.0) = no raking of the litter, 3.0 L of water added; R(3.0) = raking of the litter, 3.0 L of water added. At 38 days of age, the ammonia concentrations at litter level was significantly higher for the raked litter treatments compared to treatments of which the litter was left undisturbed. The higher ammonia concentrations measured for the raked litter treatments coincided with a higher litter pH and temperature as well as a lower uric acid and total nitrogen concentration in the litter at 37 days of age. This suggests higher microbial activity in the litter and conversion of nitrogen to ammonia. The addition of water to the litter resulted in lower litter quality scores and a higher incidence of foot lesions at 29 and 37 days of age. Compacted litter resulted in lower ammonia concentrations while friable litter led to more ammonia being volatilized from the litter. The results from this study suggest that the effect of different litter parameters (moisture, nitrogen, and uric acid content, temperature, and pH) on the production of ammonia in the litter and the volatilization of ammonia from litter are interdependent. Furthermore, the physical properties of litter such as friability and compaction have a prominent impact on the chemical properties of the litter, and potentially the ammonia emissions from the broiler house.
To conclude, the source-oriented strategies studied in this thesis offer promising results with regards to ammonia reduction, though, the effect sizes vary between the strategies. Other parameters such as litter quality and composition also differ and are favourably or unfavourably influenced, depending on the strategy implemented. Except for very low crude protein diets, broiler performance is often maintained. The insights obtained from this thesis may assist the poultry sector towards a socially acceptable and more sustainable, low-emission farming system
Compare the incomparable : decision-making on priorities in youth care as a practice of moral judgement
No full textThis is the dissertation of a PhD research project conducted at the Department of Social Work and Social Pedagogy of Ghent University.
The research highlights several aspects of prioritisation at a case level in youth care. Many practitioners in social work are confronted with the task of prioritising cases. They often consider it as a necessary evil, caused by scarce resources and waiting lists. But it is also a controversial practice, accompanied by indignation and debate, because of its severe impact on the real-life accessibility of care.
This book explores how prioritisation practices relate to their policy context and what kind of decision-making takes place in these practices. To end with, the question is discussed how prioritisation can be understood as a moral and a political practice, based on the principle of social justice
Identification, phylogénie et caractérisation du profil des mycotoxines des espèces pathogènes Fusarium et Alternaria associées aux syndromes de déclin soudain et aux symptômes de flétrissement et de tâches foliaires du palmier dattier en Tunisie
No full textIn heel Noord-Afrika wordt op grote schaal dadelpalmen gekweekt. In Tunesië neemt de dadelpalm een strategische plaats in de sociaal-economische stabiliteit van semi-aride en aride gebieden. Ver-scheidene biotische en abiotische factoren kunnen de dadelpalmteelt in gevaar brengen. In 2017 observeerden we uitgebreide symptomen van plotselinge achteruitgang, bladverwelking en bladvlek-ken op dadelpalmen in zuidelijk Tunesië. Fusarium was het meest waargenomen schimmel geslacht. De sequenties van TEF1, Calm1 en RPB2 werden gebruikt om de Fusarium stammen te identifice-ren. De voornaamste gedetecteerde soort was F. proliferatum, en in veel mindere mate F. brachygib-bosum, F. caatingaense, F. clavum, F. incarnatum, en F. solani. Alle Fusarium soorten waren patho-geen en voldeden aan Koch's postulaten. De F. proliferatum stammen produceerden vooral fumo-nisinen (FB's), beauvericine (BEA), en, in mindere mate, enniatinen (ENN's) en moniliformine (MON). Alle F. brachygibbosum stammen produceerden lage gehalten BEA, diacetoxyscirpenol, en neosolaniol; twee stammen produceerden ook T-2 toxine, en een enkele stam HT-2 toxine. Fusarium caatingaense, F. clavum en F. incarnatum produceerden alleen BEA.
De F. solani stammen produceerden MON, BEA, en ENNs. Voor het derde syndroom, bladvlekken, worden Alternaria soorten worden echter gerapporteerd als de meest frequente ziekteverwekkers. Vijftig stammen werden geïsoleerd en geïdentificeerd als Alternaria en Curvularia. Door sequentie-bepaling van de allergen-alt-1a, GPD en calm1 genen konden we 35 stammen, geïdentificeerd als A. arborescens, A. tenuissima en A.alternata soorten, en 10 stammen, geïdentificeerd als A. consortialis. Op basis van de analyse van de seqentie van de gecombineerde Internal Transcribed Spacer, GPD en Elongation factor, werden alle 5 Curvularia stammen geïdentificeerd als C. spicifera.
Alle Alternaria en Curvularia soorten die op dadelpalm plantjes getest werden, bleken pathogeen te zijn, en voldeden aan Koch's postulaten. Het vermogen om in vitro mycotoxinen te produceren werd geanalyseerd. Geen van de A. consortialis stammen produceerde enig mycotoxine, terwijl meer dan 80% van de stammen uit de Alternaria sectie zeer wisselende hoeveelheden van meerdere mycotoxi-nen produceerde, zoals AOH, AME, TEN en TA. Bovendien produceerde 40% van de stammen van de Alternaria sectie ook ALT. We testten ook de productie van FB's. Enkel de C. spicifera stammen vertoonden het vermogen fumonisinen te produceren.
Dit werk rapporteert voor het eerst een uitgebreide multidisciplinaire studie van schimmel pathogene soorten die in verband gebracht worden met sudden decline disease, bladverwelking en bladvlekken op dadelpalmen, waarbij zowel fytopathologische als voedselveiligheids kwesties aan de orde komen.
De gevoeligheid van de isolaten voor zeven fungiciden werd geëvalueerd zowel in in vitro proeven als in het veld. In vitro bleken de contactfungiciden uitstekend te werken. Van de doordringende fungiciden vertoonde Luna Experience een hogere werkzaamheid tegen Fusarium soorten om de myceliumgroei te remmen. Ook vertoonde het een vergelijkbaar effect tegen Alternaria en Curvula-ria soorten. Wat contactfungiciden betreft, werd de beste remming gerapporteerd voor Biobac WP. En het derde fungicide dat een uitstekende werking tegen Alternaria vertoonde was Carial Top. Een veldproef met deze drie beste fungiciden tegen dadelpalm bladziekte veroorzaakt door A. arbores-cens, bevestigde hun werkzaamheidDate palm (Phoenix dactylifera L.), is widely cultivated across North Africa. In Tunisia, with about 300 thousand tons of fruits produced per year, date palm occupies a strategic place in the socio-economic stability of semiarid and arid regions. Several biotic and abiotic factors can compromise date palm cultivation. In 2017–2018, extensive symptoms of sudden decline, leaf wilt symptoms were and leaf spots observed on date palms in southern Tunisia. Based on morphological identification, Fusarium was the most frequent fungal genus detected. A sequencing of translation elongation factor, calmodulin, and second largest subunit of RNA polymerase II genes was used to identify 63 representative Fusarium strains at species level and investigate their phylogenetic relationships. The main species detected was F. proliferatum, and at a much lesser extent, F. brachygibbosum, F. caatingaense, F. clavum, F. incarnatum, and F. solani. Pathogenicity on the ‘Deglet nour’ variety plantlets and the capability to produce mycotoxins were also assessed. All Fusarium species were pathogenic complying Koch’s pos-tulates. F. proliferatum strains produced mainly fumonisins (FBs), beauvericin (BEA), and, to a lesser extent, enniatins (ENNs) and moniliformin (MON). All F. brachygibbosum strains pro-duced low levels of BEA, diacetoxyscirpenol, and neosolaniol; two strains produced also T-2 toxin, and a single strain produced HT-2 toxin. Fusarium caatingaense, F. clavum, F. incar-natum produced only BEA. F. solani strains produced MON, BEA, and ENNs
Enabling interactive querying for latency-sensitive applications on big datasets
No full textIn de moderne hyperverbonden wereld laat vrijwel elke interactie die we hebben met onze omgeving een digitaal voetspoor achter. Organisaties in alle sectoren wenden zich steeds meer tot technologieën die zich in het domein van het zogenaamde Internet of Things (IoT) bevinden om hun activiteiten te monitoren en data over hun bedrijfsactiviteiten te verzamelen. Naarmate de hoeveelheid, de verscheidenheid en de complexiteit van data groter worden, neemt ook de moeilijkheid toe om er inzichten uit te verwerken, te analyseren en te distilleren. Dergelijke big data zijn de mogelijkheden van traditionele technologieën voor databeheer al lang ontgroeid. De meeste dataverwerking die tegenwoordig wordt uitgevoerd, is nog steeds voornamelijk gebaseerd op methoden geschikt voor de verwerking van batches waarvan bekend is dat ze een aanzienlijke responstijd met zich meebrengen. Hierdoor lopen organisaties het risico beslissingen te nemen en actie te ondernemen op basis van verouderde data, met name voor tijdkritische toepassingen die op deze grote, meerdimensionale dataverzamelingen draaien. Deze thesis heeft daarom als doel om onderzoek te doen naar de realisatie van interactieve query’s met een lage responstijd die op grote multidimensionale datasets uitgevoerd worden
Targeting Transient Receptor Potential channels to modulate the gastro-intestinal function in the weaned piglet : the potential of cinnamaldehyde
No full textThis thesis explored the interaction between phytogenic feed compounds and transient receptor potential (TRP) channels. These cation channels are expressed on sensory neurons in almost every tissue of the body, where they contribute to sensory transduction of stimuli. Recent evidence indicates that TRP channels are also expressed in non-neuronal cell types in rodents, associated to the release of a range of gut peptide hormones suggesting that they might be involved in the regulation of gut function. Targeting TRP channels with phytogenic compounds would result in the release of gut peptide hormones regulating gastric emptying and improving protein digestion in the weaned piglet. After a characterisation along the gastrointestinal tract of the weaned piglet focussing on TRPA1 and TRPV1, the potential of both capsaicin and cinnamaldehyde to stimulate the release of cholecystokinin and glucagon-like peptide 1 was studied. Here, cinnamaldehyde as a TRPA1 agonist, was suggested as the most promising candidate to modulate gastric function, by activating intestinal brake mechanisms. After exploring its structural features important for its bioactivity, a pelletized formulation of cinnamaldehyde was developed, to optimally target TRPA1 in the gut. Newly weaned piglets were fed with two doses of pelletized cinnamaldehyde. Cinnamaldehyde failed to affect TRPA1 mRNA abundance at the desired location without resulting in any major effect on protein hydrolysis and digestibility. This thesis created more knowledge towards the mode of action of cinnamaldehyde and its interaction with TRP channels, and will contribute to rationalize its use in piglets
From captured carbon to food : assessing production routes, cultivation strategies and their impact on the yield and quality of microbial protein from C1 compounds
No full textData-driven symbolic models for mechatronic system identification and control
No full textThe primary goal of this doctoral thesis is to automate the process of finding ‘white-box' models that are interpretable and consist of symbolic equations with focus on mechatronic systems.
To achieve this goal, we develop new algorithms for discovering mathematical models using symbolic regression. We focus on the application of symbolic regression towards mechatronic system identification, i.e. finding a symbolic expression for the governing input-output relationship of a complex mechatronic system; and control, i.e. discovering the control law from data.
Our primary research goal is realized through three subgoals: (i) automated model building for system identification and control, (ii) automated model selection and (iii) realization of symbolic models and their application on mechatronic systems, namely mechanical Duffing oscillator, electric induction machine and weaving mill as examples of mechatronic systems.
The developed algorithms and methods bring us many steps closer to the goal of realizing automated mathematical model extraction on physically dynamic systems in which the modeling cost is simplified and the user interaction can be limited or even eliminated.Het primair doel van dit doctoraal proefschrift is het automatiseren van het proces om `white-box' modellen op te bouwen die intepreteerbaar en extrapoleerbaar zijn en bestaan uit symbolische vergelijkingen. Dit met een specifieke focus op mechatronische systemen. Voor het verwezenlijken van dit doel ontwikkelen we nieuwe algoritmen voor het ontdekken van wiskundige modellen gebruik makende van symbolische regressie. We focussen op het toepassen van symbolische regressie voor (a) mechatronische systeemidentificatie, met name het vinden van symbolische vergelijkingen die het input-output gedrag van het complexe mechatronische systeem beschrijven. (b) mechatronische regeling, meer bepaald het ontdekken van regelwetten op basis van data. Het onderzoek bestaat uit volgende drie deeldoelen: (i) automatische modelvorming voor systeemidentificatie en controle, (ii) automatische modelselectie, (iii) realiseren van symbolische modellen en deze toepassen op mechatronische systemen, namelijk op een mechanische Duffing oscillator, elektrische inductiemachine, en een weefgetouw systeem die dienst doet als mechatronisch voorbeeld. De ontwikkelde algoritmen en methoden brengen ons heel wat stappen dichter bij het doel om wiskundige modellen voor fysische dynamische systemen te gaan extraheren waarbij de modelleringskost wordt vereenvoudigd en de gebruikersinteractie beperkt tot zelfs geëlimineerd kan worden
