| 1. |
- Almqvist, Viktor
(författare)
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Who you gonna call? Examining the possibilities of remote veterinary meat inspection
- 2021
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Doktorsavhandling (refereegranskat)abstract
- Demand for locally produced meat from small-scale slaughterhouses and game-handling facilities brings severe logistical challenges in meat inspection, since such facilities are often situated in rural areas and the costs and time associated with inspection visits to remote establishments are significant. With advances in technology, it might be possible to conduct meat inspections remotely via video link. This thesis aims to determine the performance of remote inspections, both ante mortem and post mortem, where a guided, untrained assistant present at the slaughterhouse relays video and sensory impressions to a veterinarian off-site. Performance was evaluated based on agreement between remote and on-site inspections. As part of this, a practical technological solution, with emphasis on a less-is-more approach, was conceived, assembled and tested in practical use. Comparisons between methods were conducted using Cohen’s kappa-based statistics. On directly comparing findings under 26 different inspection codes or classifications recorded by two veterinarians conducting inspections on 400 carcasses and organs of pigs at a Swedish large-scale slaughterhouse, it was found that the level of agreement between the two methods was generally high, with most findings scoring ‘almost perfect agreement’. When ante mortem inspections were evaluated in a similar way, it was concluded that, due to extremely low prevalence of findings, ante mortem inspections are difficult to perform remotely under current conditions. In conclusion, remote post mortem veterinary inspections appear very promising, but the method needs to be evaluated further.
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| 2. |
- Alwall Svennefelt, Catharina
(författare)
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Occupational injuries and communications in Swedish agriculture safety interventions
- 2019
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Doktorsavhandling (refereegranskat)abstract
- Systemic changes in Swedish agriculture have seen the average farm size increase, employees become more common, adoption of new technologies and an ageing farm population. This has led to many new physical and psychological health risks and the need for continued work in preventing occupational injuries. To date, education has been the main tool (in terms of total spending) used by stakeholders to influence work safety behaviour. However, this approach has been criticised by occupational safety experts for being inefficient, if not largely ineffective. It is often unclear whether the education tool itself or its implementation is the problem. Given the need to improve safety at work within agriculture and identify the mechanisms underlying intervention outcomes, this thesis explored work safety interventions in Sweden and sought to develop a deeper understanding of how motivation can be used to effect behavioural change and the underlying cognitive factors promoting or hindering these changes. Over a six-year period, four studies were carried out using mixed methods and covering topics such as occupational safety intervention implementation, outcomes, fear appeals and cognitive mediation processes. The results confirmed that there is marked under-reporting of occupational injuries in Sweden. More importantly, they showed that, despite substantial efforts to reduce occupational injuries, on taking into account the reduced labour demand in agriculture and the decline in the number of farms since 2004, the rate of occupational injuries has not significantly decreased. Fear appeals were found to be the most common motivational tool used by the largest organisations in Sweden to influence work safety behaviours. Use of an extended parallel processing model (EPPM) to describe and evaluate marketing communications revealed a mismatch between the types of threats used in communications and the behaviours promoted. Contradictory evidence was also found. On the one hand, some farmers interviewed seemed to be aware of the most common threats in their environment and nearly all had made at least some changes to their work safety environment (crediting an intervention that took place one year earlier), indicating that the intervention had worked in terms of generating awareness and stimulating adaptive behaviours. On the other hand, many of the same farmers who had made adaptive changes also showed clear signs of maladaptation. These insights can be applied to address the communication motivation and cognitive challenges in safety interventions in Swedish agriculture.
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| 3. |
- Auckburally, Adam
(författare)
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Optimising pulmonary gas exchange in anaesthetised horses : unravelling the role of pulsed inhaled nitric oxide using computed tomography angiography of the lung
- 2021
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Doktorsavhandling (refereegranskat)abstract
- Mortality rates in healthy, anaesthetised horses are higher than in most other species. Hypotension, hypoxaemia and hypoventilation are implicated as risk factors, which develop due to the combined effects of general anaesthesia and recumbency. Hypoxaemia is largely a consequence of ventilation perfusion (V̇ /Q̇ ) mismatch. When horses are recumbent, dependent areas of lung become compressed and collapse. These atelectatic lung regions receive a large proportion of pulmonary blood, do not participate in gas exchange and contribute significantly to venous admixture. Whilst the hypercapnia associated with hypoventilation is easy to manage, treatment of hypoxaemia is more challenging. Mechanical ventilation (MV) is often employed, but can have detrimental effects, and the response to it is unpredictable. Pulsed inhaled nitric oxide (PiNO), has been used successfully to manage hypoxaemia in anaesthetised horses. The presumptive mechanism of action is via redistribution of pulmonary perfusion, from dependent areas of lung, to better ventilated, non-dependent lung regions. This movement of blood occurs due to the selective, pulmonary vasodilatory effect of PiNO. However, it necessary to further elucidate the mechanism of action of PiNO. The aims of these studies were to: develop a CT method to quantify regional pulmonary perfusion in the equine lung; measure changes in regional pulmonary perfusion when PiNO is administered, during spontaneous breathing (SB) and MV and; measure changes in pulmonary perfusion in response to PiNO during SB and MV in hypotensive and normotensive horses. The CT method could reliably measure changes in aerated and atelectatic regions of lung, and compared well to previously reported values measured using microspheres. During SB and MV in the normotensive horse, PiNO caused a redistribution of blood to non-dependent lung regions which led to improvements in gas exchange. Unexpectedly, PiNO was ineffective during MV if horses were hypotensive. However, during SB, the response to PiNO was similar regardless of blood pressure. By developing a new CT method with angiography for studies of the distribution of pulmonary perfusion, these experiments have shown that PiNO is an effective and safe treatment option for hypoxaemic horses, but blood flow and blood pressure must be supported if horses are mechanically ventilated.
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| 4. |
- Gatiso, Tsegaye Ginbo
(författare)
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Essays on heterogeneity and uncertainty in climate policy and development
- 2021
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Doktorsavhandling (refereegranskat)abstract
- This thesis consists of four papers focusing on the role of heterogeneity and uncertainty in the context of climate change policy and agricultural development. By using intra-household data, the first paper illustrates differences in spouses’ perception of climatic risks and its effect on household’s adoption of climate change adaptation in sub-Saharan Africa. In Kenya, female spouses’ perception of climatic risks increases the household’s likelihood of adopting climate adaptation strategies, whereas males’ perception has no statistically significant effects. The adoption of livestock-based strategies for climate change adaptation is positively associated with both female and male spouses’ perceptions of climatic risks in Uganda, whereas it has a negative relationship with females’ perception in Tanzania. Moreover, both male and female spouses’ perceptions of climatic risks have positive associations with households’ likelihood of adopting crop-based strategies for climate change adaptation in Uganda and Tanzania. The second paper assesses how the impacts of climate change vary across crops and across agro-ecosystems in Ethiopia using the household-level panel data. The empirical results show that climate change will induce an increase in coffee and teff yields at high altitudes while it will decrease coffee yield at low altitudes, and barley, maize, and wheat yield at high altitudes by the years 2041-2060. The third paper provides a systematic review of literature that uses a real-options approach for the analysis of investment in climate adaptation and mitigation actions. The review shows the need of future research incorporating climate uncertainty, risk preferences, and decisions-makers’ strategic interactions. The fourth paper models farmers’ opportunity to relocate coffee farms to higher altitudes in Ethiopia as climate adaptation strategy. The results illustrate how the uncertainty in net returns and high establishment costs may induce farmers to postpone their adaptation actions. The findings of papers presented in this thesis point to the need to take into account the differences in individual behaviours, vulnerabilities and uncertainties in designing climate and development policies.
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| 5. |
- Iqbal, Mudassir
(författare)
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Biological control of plant-parasitic nematodes by the fungus Clonostachys rosea
- 2019
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Doktorsavhandling (refereegranskat)abstract
- Plant diseases caused by plant-parasitic nematodes are serious constraints to sustainable crop production due to high yield losses, the persistent nature of these nematodes and a lack of efficient control methods. Biological control is a promising approach to reduce plant diseases caused by nematodes.This study investigated the effect of the fungus Clonostachys rosea strain IK726 on nematode populations in a naturally nematode-infested soil planted with wheat in a climate chamber under controlled conditions. Populations of plant-parasitic nematodes extracted from soil and roots were 40 to 73% lower in soils when C. rosea was applied than in untreated soils, whereas non-parasitic nematodes were unaffected. Soil inoculation with C. rosea increased the shoot weight and shoot length of wheat plants by 20 and 24%, respectively. Light microscopy of in vitro C. rosea–nematode interactions did not reveal evidence of direct parasitism; however, culture filtrates of C. rosea grown in potato dextrose broth (PDB) exhibited toxicity towards nematodes and immobilized nematodes. A genome-wide analysis of protease genes showed that C. rosea contains more protease genes than other studied biocontrol fungi. A computational analysis of gene family evolution revealed a high gene copy number of serine protease subfamilies S8A, S9X and S33 in C. rosea, suggesting the involvement of these proteases in biotic interactions. A genome-wide association analysis of 53 strains of C. rosea further identified 279 single-nucleotide polymorphism markers that were significantly associated with the in vitro antagonism trait against plant-parasitic nematodes. Two non-ribosomal peptide synthetase (NRPS) genes (nps4 and nps5) were identified in genomic regions associated with nematicidal activity whereas nps1 was included based on previous published reports of functional studies. Gene deletion strains of nps1, nps4 and nps5 were generated and showed increased growth and conidiation rates. Culture filtrates from C. rosea Δnps1, Δnps4 and Δnps5 strains exhibited reduced nematicidal activity and immobilized lower numbers of nematodes compared with the wild type after 24 h of incubation. However, NRPS deletion strains still possessed some nematicidal activity compared with the PDB control treatment, which may be due to the presence of additional nematicidal compounds or enzymes (e.g., serine proteases). Furthermore, Δnps1, Δnps4 and Δnps5 strains showed reduced biocontrol efficacy in a naturally nematode-infested soil in a pot experiment and failed to reduce populations of nematodes in soil or in roots of wheat as efficiently as the wild type strain.This study demonstrates that C. rosea can control plant-parasitic nematodes and improve the growth of plants at the same time. The antagonistic potential of C. rosea could be used to control plant-parasitic nematodes, which may contribute to reduced applications of chemicals as part of an integrated pest management programme.
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| 6. |
- Jupiter, Kristofer
(författare)
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The function of open fields : agriculture in early modern Sweden
- 2020
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Doktorsavhandling (refereegranskat)abstract
- This thesis examines the spatial arrangement of holdings and villages in early modern open fields, the dominating system in large parts of Europe for nearly a millennium. Open fields is characterised by the spatial division of holdings, scattered and intermingled in one or more fields. The thesis examines the practical aspects of open field farming and the function of scattered holdings, and the aim is to study how scattered holdings were integrated into farming practice and the larger institutional and communal arrangement of open fields the mixed farming system. Open fields in southwest Sweden are analysed empirically on farm, village and inter-village level using historical maps. Methodologically, maps are combined with written sources for spatial and temporal analysis and estimates of time consumption in cultivation and transportation. Furthermore, it analyses the distribution of plots in two different field systems and discusses the efficiency of small-scale production and area-productivity in open fields, and cooperation between villages and reconstructions and analysis of fence-organisations.This thesis shows that scattered and intermingled holdings facilitated an efficient management of time, work and space. The open fields allowed for spatial and temporal sequence of work and diversification crops. What ultimately defines an open field is both the openness of a physical landscape, fence or unfenced and, more so, the requirement of the cooperation between its participants and synchronisation of key activities of farming.
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| 7. |
- Karlsson, Maria
(författare)
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Stability of ultra-high temperature treated milk : the effect of raw milk quality, storage temperature and storage time
- 2019
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Doktorsavhandling (refereegranskat)abstract
- The composition and properties of raw milk are important for the stability of dairy products, especially for products with long shelf-life, e.g. ultra-high temperature (UHT) treated milk. In the UHT process, milk is subjected to temperatures above 135 °C for a few seconds, resulting in a product that can be stored for several months at ambient temperature.This thesis investigated how natural variations in the composition and properties of raw milk affected the stability of UHT milk during long-term storage at different temperatures. For this purpose, samples of unprocessed raw milk as well as the resulting UHT milk were obtained every month for one year from a commercial dairy plant. Additionally, in a full factorial experiment, milk was modified with respect to levels of calcium, citrate and urea to investigate the effect on the stability of the resulting UHT milk.The quality traits analysed in the raw milk included composition, bacterial counts, enzymatic activity, colour and measures of stability, i.e. heat coagulation time (HCT) and alcohol test. During storage of UHT milk, sensory attributes and stability measures were analysed. Multivariate statistics was used to identify batches of milk showing similarities with respect to total variation.There were only small natural variations in the composition and properties of raw milk. Elevated calcium content, and associated decrease in pH, had a strong negative effect on the stability of UHT milk. Higher concentrations of citrate and urea in milk did not affect the stability compared with unmodified reference UHT milk.Storage temperature correlated with colour and pH, whereas storage time correlated with creaming, sedimentation and HCT. Cold (4 °C) or ambient (20 °C) storage gave the longest shelf-life, limited by sedimentation and deviating taste. In UHT milk stored at 30 or 37 °C, the shelf-life was limited by several parameters, including colour, taste and sedimentation. Changes in the stability of UHT milk during storage are suggested to be explained by known mechanismKnowledge of how the composition and properties of raw milk affect the stability of the resulting product can aid the dairy industry to more accurately predict the shelf-life of UHT milk. Better understanding of how storage conditions affect the shelf-life of UHT milk can provide useful guidance to consumers on appropriate storage temperature.
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| 8. |
- Kokla, Anna
(författare)
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Haustoria regulation in the facultative parasitic plant Phtheirospermum japonicum
- 2022
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Doktorsavhandling (refereegranskat)abstract
- Parasitic plants are important agricultural pests that lead to considerable yield losses annually. Parasitic plants that completely rely on their hosts for their survival are known as obligatory parasites, whereas those independent of their hosts but parasitize under the right conditions are known as facultative parasitic plants. All parasitic plants form a multicellular organ termed the haustorium via which they invade their host, establish vascular connections and uptake water and nutrients. Despite recent advances in our understanding of parasitic plants, the mechanisms of haustoria regulation remain largely unknown. Here we aimed to identify how the environmental nutrient status affects haustoria formation in the facultative parasitic plant Phtheirospermum japonicum. We showed that P. japonicum inhibits haustoria formation in response to the macronutrient nitrogen and that this nitrogen-mediated haustoria inhibition is mediated by the hormone abscisic acid (Paper I). Further investigation of haustorium regulatory mechanisms demonstrated that P. japonicum harbors a haustoria autoregulation mechanism (AOH) that utilizes a long-distance signalling mechanism that involves small mobile peptides (Paper II). Lastly, we investigated the role of cell wall modifying enzymes in haustoria and xylem bridge formation. We identified two genes encoding cell wall modifying enzymes, one pectin methylesterase and one pectin methylesterase inhibitor, that are involved in both haustoria and xylem bridge formation in P. japonicum (Paper III). Overall this thesis contributes to our understanding of haustoria regulation in response to nitrogen availability or pre-existing established haustoria.
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| 9. |
- Loots, Sonja
(författare)
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Habitat characteristics, genetic diversity and conservation concerns for the genus Lithops in Namibia
- 2019
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Doktorsavhandling (refereegranskat)abstract
- The dwarf succulent genus Lithops (Aizoaceae) is endemic to southern Africa, with 16 species in Namibia. Lithops are vulnerable to a variety of threats and assignment of accurate conservation status is difficult due to insufficient information about population parameters and influence of habitat variables. In addition, taxa are defined according to leaf characters that may be adapted to plant habitat, resulting in over-classification. Plant density, spatial arrangement of plants and habitat profile was investigated in a 1 ha study area in a population of L. pseudotruncatella. Five out of seven plant density estimation methods vastly over- or under-estimated plant number as determined in a census. Plant number in 100 10×10 m test plots was positively associated with a higher percentage cover of gravel and pebbles as opposed to sand or stones, and with a gentle rise as opposed to slopes and depressions. Plant abundance and habitat variables were also evaluated in 9 populations of L. ruschiorum. Evaluation of the 51 and 43 sites of the meticulously studied RUL population, and the remaining 8 populations, respectively, showed that plant density and/or plant number was associated with aspect, slope, soil texture, substrate and geographic distance from the coast. Results are concordant with a strong impact of fog-based precipitation on plant density in the coastal populations, whereas rain is probably more important at RUL, situated further inland. Plant number dropped by 50% in 21 10×10 m plots monitored at RUL over nine years, most likely due to a prolonged drought in 2012–2016. Plant number declined also in some of the 15 plots in the other populations. AFLP markers were employed to study 52 individuals from 7 populations of L. ruschiorum, and 223 individuals from 44 populations representing 15 Lithops species and 23 taxa in total. An AMOVA demonstrated low levels of genetic differentiation between populations of L. ruschiorum, and a significant but rather weak isolation-by-distance pattern. Analyses of genetic structuring and phylogenetic relationships identified several groups of closely related species, while subspecific taxa often overlapped considerably. Main reason for the overall low variability in Lithops is probably a rapid and recent diversification of succulents after the global expansion of arid environments in the late Miocene. Three nomenclatural changes were made, affecting: (1) L. optica and L. herrei, (2) L. amicorum and L. karasmontana, and (3) subspecies bella and eberlanzii of L. karasmontana.
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| 10. |
- Martin, Frida
(författare)
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From field to genetics : anthelmintic resistance in the equine roundworm Parascaris univalens
- 2021
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Doktorsavhandling (refereegranskat)abstract
- The equine roundworm Parascaris univalens is a common parasite of foals. Most foals show mild clinical symptoms, but large worm burdens can lead to severe colic and even death. Regular treatment with anthelmintic drugs has resulted in resistance development, mainly to ivermectin but also to pyrantel and fenbendazole in sporadic cases. In Sweden, resistance to ivermectin is considered to be widespread.The aim of the thesis was to examine the efficacy of anthelmintic drugs on stud farms in Sweden and Iceland, develop novel models for research and study genetic mechanisms potentially involved in drug metabolism and anthelmintic resistance.Faecal egg count reduction tests showed that resistance to both pyrantel and fenbendazole has emerged on Swedish stud farms, and that ivermectin resistance is common on Icelandic farms. Due to the potentially lethal consequences of infection, this is a serious situation. We developed a novel method to hatch P. univalens eggs in order to use larvae in in vitro experiments to study resistance mechanisms. Quantitative PCR, RNA sequencing and amplicon sequencing were used to study genetic and transcriptomic mechanisms behind anthelmintic resistance in P. univalens. Several genes coding for drug metabolising enzymes, transport proteins and a possible drug target for ivermectin were found to be differentially expressed in P. univalens after exposure to anthelmintic drugs. However, mutations in β-tubulin genes responsible for benzimidazole resistance in many other parasitic nematodes were not present in a fenbendazole-resistant P. univalens population. In conclusion, the current level of resistance in P. univalens has been updated in this thesis, a novel research method has been developed and novel candidate genes for future research have been identified.
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