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Selle kollektsiooni püsiv URIhttp://hdl.handle.net/10492/2499

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  • Kirje
    Distribution patterns, inter-and intra-host dynamics of an emerging salmonid parasite T. bryosalmonae across temporal and spatial scales
    (Estonian University of Life Sciences, 2024) Lauringson, Magnus; Vasemägi, Anti; Päkk, Priit; Institute of Veterinary Medicine and Animal Sciences; Ros, Albert (opponent)
    Global climate change is shifting the physical and chemical properties of freshwater ecosystems, involving increased water temperature, altered hydrological regime and nutrient concentrations. These changes influence particularly cold-water macro vertebrates, such as salmonids, resulting in loss of habitat and population declines. The physiochemical alternations caused by climate change also have an effect on the biotic environment, including changes in virulence, pathogenicity, distribution and prevalence of pathogens and diseases. One emerging widespread illness is salmonid specific proliferative kidney disease (PKD), caused by myxozoan parasite Tetracapsuloides bryosalmonae, which is primarily affecting juvenile fish during their first growth summer. PKD causes hyperplasia in kidney and spleen tissue, anemia and external clinical signs include abdominal swelling and pale gills. Myxozoans are endoparasites, who have evolved from free-living cnidarians and typically possess a complex two-host life-cycle, involving an invertebrate and vertebrate host. For myxozoan T. bryosalmonae, cycling occurs between freshwater bryozoans and salmonid hosts. In Europe, native brown trout (Salmo trutta), Atlantic salmon (Salmo salar), European grayling (Thymallus thymallus), Arctic charr (Salvelinus alpinus) and European whitefish (Coregonus lavaretus), as well as non-native rainbow trout (Oncorhynchus mykiss) are susceptible to T. bryosalmonae (for review see Ros et al., 2022). While the severity of PKD is strongly dependent on water temperature, with disease symptoms progressing with rising temperature, only a few studies have found T. bryosalmonae in northern regions. Moreover, detailed knowledge on the parasite distribution and prevalence is not available in northernmost regions of Europe. Earlier PKD related research has also primarily been centered around juvenile salmonids, with the main focus on farmed rainbow trout (Oncorhynchus mykiss) and wild brown trout (Salmo trutta) in single host systems. Investigation of T. bryosalmonae resistance and tolerance patterns in sympatric wild salmonid populations is therefore expected to improve our understanding on parasite dynamics and host defence mechanisms. It has been speculated that migrating fish could act as parasite vectors, however it is unclear, if and how anadromous salmonid species contribute to the parasite’s life-cycle during their later life-stages. The specific foci of the current thesis was to cover the abovementioned knowledge gaps by investigation of T. bryosalmonae distribution, prevalence and infection dynamics at different spatial and temporal scales with an addition of intra-host and inter-host dimensions. The thesis revealed how T. bryosalmonae is widely distributed within rivers flowing into the Barents and Norwegian Sea in Northernmost Europe, which indicates that T. bryosalmonae is already present in the region and future climate change and heat waves may likely cause new disease outbreaks in northern latitudes. T. bryosalmonae infection typically occurs during the first growth summer of salmonid fish. However in northernmost Europe, it was found that almost exclusively all young-of-the-year fish were uninfected with the parasite and infections primarily occur among yearlings. It was also apparent that the average summer water temperature was remarkably higher in rivers to host the parasite. Inter-species comparison revealed that brown trout (Salmo trutta) is more frequently infected with the parasite than Atlantic salmon (Salmo salar) in sympatric populations of northernmost Europe. The second study shed light onto inter-specific PKD susceptibility through investigating changes in T. bryosalmonae load and the severity of disease signs (renal hyperplasia, haematocrit) in wild sympatric brown trout and Atlantic salmon populations. Parasite burden and clinical progression of PKD demonstrated highly distinct patterns between sympatric Atlantic salmon and brown trout. While both species initially showed low levels of parasite load, the rate of parasite multiplication was much faster in brown trout compared with Atlantic salmon. However, despite this slower build-up, the amount of parasite DNA reached similar levels in both species by the end of September. This indicates that the speed of parasite multiplication, rather than the absolute number of parasites in the host kidney, may be an important factor causing between-species variation in the disease susceptibility. Comparing parasite load with disease symptoms demonstrated a strong difference in disease tolerance between Atlantic salmon and brown trout. In the beginning of August, renal hyperplasia slightly increased for both species. However, despite the homogeneous build-up of parasite burden between the host species, kidneys of Atlantic salmon recovered by the end of the season. On the other hand, brown trout developed a severe kidney hyperplasia by the end of September with a considerable inter-individual variation. The results demostrate that Atlantic salmon is more resistant than brown trout against T. bryosalmonae. T. bryosalmonae is often found within juvenile salmonids in rivers hosting anadromous salmonid populations, however we knew very little on parasite presence within anadromous adult fish, who have exploited marine environment for several years. Wide-scale T. bryosalmonae sampling among adult sea trout caught from the marine environment within the Estonian coastal area indicated that more than one third of Estonia’s sea trout are infected with the parasite during their marine feeding phase. Spatial analysis revealed an increasing infection trend among the adult fish from south to north and west to east along the coast of Estonia, which mirrored T. bryosalmonae prevalence patterns in nearby rivers and streams. Based on age determination within the sampled sea trout via otoliths, it was observed that the parasite can even be detected in up to six-year-old sea trout and probability of infection increases with age, demonstrating that infections or re-infections can occur in later life stages of the anadromous fish. In all, the current thesis has advanced our understanding on T. bryosalmonae prevalence in different spatial, inter-host and intra-host scales, contributing towards a better understanding on the host-pathogen interactions and parasite distribution in wild salmonid populations.
  • Kirje
    Campylobacter spp. in fresh broiler chicken meat and pig caecal samples in Estonia
    (Estonian University of Life Sciences, 2024) Tedersoo, Triin; Meremäe, Kadrin; Roasto, Mati; Institute of Veterinary Medicine and Animal Sciences; Zwietering, Marcel (opponent)
    Campylobacteriosis has been the most frequently reported zoonosis in the European Union (EU) since 2005. A total of 127,840 confirmed cases of human campylobacteriosis were reported in 2021, with a notification rate of 41.1 per 100,000 people in the EU. Campylobacter jejuni and Campylobacter coli are the main Campylobacter species causing 80 and 10% of human infections, respectively. The majority of Campylobacter spp. infections are mild and self-limiting. However, it can result in severe systemic illness or mortality in children, older adults, and immunocompromised individuals. Several studies have confirmed that poultry meat, especially broiler chicken meat, is the primary source of human campylobacteriosis; however, the role of pork in the development of Campylobacter enteritis in humans has not been well studied. Nevertheless, pig-derived C. coli have been linked to Campylobacter infections in humans. The current study revealed that broiler chicken meat of Lithuanian and Latvian origin sold in Estonian retail stores was contaminated with highly resistant Campylobacter spp. High genetic diversity was observed among the Campylobacter isolates from fresh broiler chicken meat samples. Genotyping has revealed a link between campylobacteriosis in Estonia and imported fresh broiler chicken meat. The antimicrobial resistance profile of Lithuanian broiler chicken meat isolates overlapped with those obtained from humans in Estonia. This implies that eating Campylobacter-contaminated broiler chicken meat could pose a potential risk to Estonians. In addition to broiler chicken meat, pork consumption can also pose a potential public health risk, as this study revealed that pigs are carriers of antimicrobial-resistant C. coli. Antimicrobial-resistant bacteria in food can reach consumers and pose a threat to their health. To mitigate the incidence of antimicrobial resistance in Campylobacter spp., it is critical to adhere to treatment guidelines for both humans and animals, as well as implement proper practices at the farm level.
  • Kirje
    Relationship between bovine colostrum particle size and composition
    (Estonian University of Life Sciences, 2024) Sats, Andres; Jõudu, Ivi; Kaart, Tanel; Lepasalu, Lembit; Institute of Veterinary Medicine and Animal Sciences; Gross, Josef Johann (opponent)
    Colostrum is one of the by-products associated with milk production. Bovine colostrum, as a source of bioactive and functional components, has been studied for decades. When developing and optimizing processing technologies, it is necessary to consider various parameters, including particle size distribution and related factors. This work aimed to fill the knowledge gaps regarding the size distribution of colostrum particles. Additionally, the relationships between particle size, colostrum composition, and some animal-specific characteristics were investigated. The diameter of fat globules in colostrum doubles during the first four consecutive milkings. The fatty acid profile in the first three milkings is similar, but differs noticeably from the fourth milking. Colostrum collected from the fourth milking onwards can be considered as transitional milk. The size of whey particles in colostrum decreases during four succeeding postpartum milkings. The size distribution of whey particles, along with immunoglobulin G (IgG) content results, indicates that a 100 nm (filter)pore size is sufficient for separating IgG particles of approximately 10 nm in diameter. Similarly, the content of casein and the diameter of casein micelles decrease during the first four postpartum milkings, but the latter remains larger than described in regular milk. Gaining knowledge about the alterations in bovine colostrum, with a particular focus on particles size distribution, is essential for both research and practical applications. Knowledge of the dynamics of casein micelle size distribution in colostrum can contribute to a better understanding of casein micelle formation mechanisms and functionality. Moreover, the collected information provides opportunities for optimizing existing colostrum valorization technologies in a more environmentally sustainable way and for developing new technologies that preserve the bioactivity and nutritional value of colostrum components.
  • Kirje
    Trichinella species in wild animals in Estonia
    (Estonian University of Life Sciences, 2024) Kärssin, Age; Lassen, Brian; Jokelainen, Pikka; Institute of Veterinary Medicine and Animal Sciences; Nöckler, Karsten (opponent)
    Trichinella infections in animals pose a worldwide public health concern, including in Estonia. The doctoral thesis comprises of five independent studies: four studies on Trichinella spp. epidemiology in wild animals and pigs in Estonia, and a study evaluating methods for detecting Trichinella spp. in meat. The results show convincingly, that wild animals, including game species play an important role as reservoirs of Trichinella spp. in Estonia. No antibodies against Trichinella spp. were found in domestic pigs, but anti-Trichinella IgG antibodies were found in 42.1% of wild boars. Trichinella infection was detected in 69.0% of red foxes, 57.5% of raccoon dogs, 0.9% of wild boars, 14.7% of brown bears, 65.6% of Eurasian lynxes, three out of five European badgers, and none of the investigated moose. Four Trichinella species were identified in Estonia: T. nativa, T. britovi, T. spiralis and T. pseudospiralis. The findings of T. pseudospiralis and T. spiralis were the first in wild animals in Estonia. In wild boars and lynxes, Trichinella spp. prevalence was higher in the northern and western regions, and significantly lower in the southeast when compared to the southwest, northwest, and northeast. Identified risk factors for Trichinella infection in wild boars and lynxes included the year, age group, and geographical unit. The high Trichinella infection pressure from wild hosts poses a risk for transmission to domestic pigs and humans via game meat consumption. Therefore, continuous monitoring is essential to collect data on changes in Trichinella epidemiology in Estonia, facilitating effective risk assessment.
  • Kirje
    Assessment of developmental potential of in vitro produced dairy cattle embryos by invasive and non-invasive methods
    (Estonian University of Life Sciences, 2024) Nõmm, Monika; Jaakma, Ülle; Kõks, Sulev; Institute of Veterinary Medicine and Animal Sciences; Leroy, Jo (opponent)
    Assisted reproductive technologies (ART) and preimplantation embryo diagnostics have become increasingly essential in cattle breeding. Artificial insemination, in vivo embryo production using superovulation and uterine flushing, collection of oocytes from live animals, and in vitro embryo production have revolutionized cattle breeding. Although these technologies have been used for decades, efforts are constantly being made to improve them. The aim of the thesis was to identify embryo developmental biomarkers and differences in gene expression patterns using various non-invasive and minimally invasive methods to assess the quality of cattle embryos before transfer. It was determined that it is possible to remove in vitro culture media from still-developing embryos without inhibiting their development. Liquid chromatography analysis did not identify any specific biomarkers predicting embryo development. Still, differences were observed in the composition of the maturation media among embryos that had reached the blastocyst stage by the eighth day. Cattle embryos produced in vitro secrete extracellular vesicles into the environment which are nano-sized particles. The concentration of these particles in the maturation media depends on the embryos’ development stage and quality. Single-cell RNA sequencing analysis can distinguish significant differences in gene expression patterns between embryos that can develop into blastocysts and those whose development stopped at the morula stage. Morula biopsy allows genetic analysis from embryos without harming them. Based on the results, it can be concluded that there is great potential for the further development of these methods to find biomarkers for embryo quality, which will be useful in cattle breeding.
  • Kirje
    Culling and longevity of Estonian dairy cows – animal-based, herd infectious and farmerrelated risk factors
    (Estonian University of Life Sciences, 2023) Rilanto, Triin; Mõtus, Kerli; Institute of Veterinary Medicine and Animal Sciences; Wittek, Thomas (opponent)
    The milk production of the cows increases every year with an accompanying decrease in their lifespan both in Estonia and other countries around the world. These trends are especially apparent in larger production farms. Intensive culling and early exit from the herd reflect poor cow health and decreased welfare but may also be related to the production goals and attitudes of the farmers. The short productive life of the cows is associated with greater environmental impact and also does not meet consumer expectations. In this thesis the effect of different factors on dairy cow culling and lifespan were analyzed. The animal-based risk, herd infectious and farmer-related risk factors of culling were investigated in Estonian large dairy farms. In the current study we found that the culling rate and longevity of cows in Estonian dairy herds are similar to results of other high production countries. The highest culling risk was related to calving problems and early post-partum period. Also, the risk of culling increased with an age of the dairy cow. The four most common reasons for culling in this study were feet and claw disorders, udder disorders, metabolic and digestive disorders, and fertility problems. Estonian large dairy herds were endemically infected with many cattle pathogens having significant impact on culling and longevity by impairing cattle health, fertility, and production. In this research was found that farm managers are generally not satisfied with the culling rate and longevity of cows. Also, the culling rate was the highest and the longevity of the cows was the shortest precisely in those dairy farms where the farm managers prioritized the achievement of high milk production more than the long life of the cows. A better understanding of the economic return of dairy cow longevity and finding the compromise between milk yields and cow health would be important for the sustainability.
  • Kirje
    Cytological endometritis in dairy cows: diagnostics, effects on fertility, and associations with metabolic stress
    (Estonian University of Life Sciences, 2023) Valdmann, Merle; Valdmann, Andres; Institute of Veterinary Medicine and Animal Sciences; Opsomer, Geert (opponent)
    Dairy cow fertility and longevity are major concerns. A high prevalence of calving-related disorders and clinical diseases (DIS) in dairy herds is not unusual. One and a half months after parturition, approximately 30% of cows experience uterine inflammation, characterised by an increased proportion of white blood cells, more specifically polymorphonuclear neutrophils in the uterine lumen—a disease termed cytological endometritis (CYTO). CYTO is associated with a decreased conception rate and higher culling risk. In this thesis, we improved tools for CYTO diagnosis by developing an innovative device that allows the collection of uncontaminated uterine smear samples for cytological and microbiomic investigations. We studied the influence of CYTO on the fertility and culling of clinically healthy and unhealthy dairy cows and investigated the associations of metabolic stress during the periparturient period with the development of CYTO. We found that CYTO-positive health status, irrespective of DIS status, decreased the pregnancy rate and increased the culling risk. When DIS-positive and CYTO-positive health statuses were combined, they had an additive negative effect. This finding led us to conclude that the variation in the effects of clinical disease on reproduction can at least partly be explained by the occurrence of CYTO. Multiparous dairy cows were at greater risk of experiencing CYTO diagnosed at 40 days after calving if they showed low plasma insulin-like growth factor-1 concentrations at two weeks prepartum and/or at one week postpartum. In addition, a low precalving body condition score and DIS were associated with the development of a positive CYTO status. Practical advice to farmers would be to aim to minimise metabolic stress during the periparturient period to support dairy cow fertility. In dairy herds with fertility problems, special attention needs to be paid to the occurrence of CYTO, both in DIS-positive and clinically healthy cows
  • Kirje
    Cryptosporidium spp. prevalence, relationship with the general inflammatory response, faecal microbiota and halofuginone lactate treatment in calves
    (Estonian University of Life Sciences, 2023) Dorbek-Kolin, Elisabeth; Orro, Toomas; Institute of Veterinary Medicine and Animal Sciences; Adjou, Karim Tarik (opponent)
    Calf diarrhoea is a common problem in cattle herds, and it has many causative agents including the protozoan parasites of the genus Cryptosporidium. This parasite is detected worldwide and has clinical importance particularly in pre-weaned calves. The most common species in calves is Cryptosporidium parvum. In this thesis, the prevalence of Cryptosporidium spp. in Estonian calves was determined, which species of this parasite were shed with faeces, and which subtypes of C. parvum were shed. Additionally, associations of Cryptosporidium species, general inflammatory response, and faecal microbiota were studied. The effects of treatment with halofuginone lactate were evaluated. Cryptosporidium spp. are widely spread among Estonian calves during their first two months of life. In this thesis, three species were detected, and ten subtypes of C. parvum were described, one of them being novel. Shedding of Cryptosporidium spp. oocysts was most common during the second week of life. The general inflammatory response was measured through blood serum concentrations of acute phase proteins (specifically serum amyloid A and haptoglobin), that are synthesised in liver as a result of pathogen invasion or tissue damage. The more Cryptosporidium spp. oocysts the calves shed in their faeces, the higher the concentration of these proteins in the blood, and the lower the microbial diversity in faeces. Some bacterial genera in faeces were positively associated with the serum concentrations of the acute phase proteins (e.g., Fusobacterium), or negatively with cryptosporidiosis (e.g., Ruminiclostridium 9). Halofuginone lactate treatment decreased mortality of calves and delayed the oocyst shedding. Understanding the interactions of Cryptosporidium spp., host responses, and the microbiota of the calf can help to comprehend the development of the calf as a whole. Based on this knowledge, factors benefiting the welfare and performance of production animals could be found and possibly influenced.
  • Kirje
    Prevalence and counts of Listeria monocytogenes and Campylobacter spp. in food and molecular characterisation of the isolates in Estonia
    (Estonian University of Life Sciences, 2022) Mäesaar, Mihkel; Roasto, Mati; Institute of Veterinary Medicine and Animal Sciences; Møller Nielsen, Eva (opponent)
    Listeria monocytogenes is a bacterial zoonotic agent and a major cause of listeriosis in humans. The invasive form of listeriosis causes severe illness and can be fatal. In the European Union (EU), 2,621 cases of listeriosis were reported in humans in 2019, with a 17.6% case fatality rate. A study carried out in 2012–2013 found that 16.8% of the 185 samples of ready-to-eat fish (RTE) products tested positive, but only one salted and sliced salmon fillet product exceeded the European Union food safety criterion of 100 CFU/g at the end of its shelf-life. Unlike L. monocytogenes, infections caused by Campylobacter jejuni are significantly more common in humans. Campylobacteriosis usually affects people with mild symptoms and is typically a self-limiting disease. In 2019, 220,682 cases of campylobacteriosis were registered in the EU, but the mortality rate per case was only 0.03% compared to listeriosis. A survey conducted in 2012 found that 35.0% of the 220 samples of fresh broiler chicken meat from Estonia, Latvia and Lithuania sold in Estonia were contaminated with campylobacters. Higher prevalence, counts and antibiotic resistance of campylobacters were associated with imported chicken broiler products. These indicators were low in fresh broiler chicken meat products of Estonian origin. The molecular methods used in the study allowed the strain of L. monocytogenes isolated from Estonian food to be associated with a multi-country outbreak of listeriosis in several European countries in 2014–2019. A retrospective survey also revealed that the same strain was already in the company's RTE fish products before the outbreak was first registered. Molecular studies also showed that the primary source of human cases of campylobacteriosis in Estonia is mainly related to poultry, including poultry meat. Systematic application of whole-genome sequencing in routine surveillance will contribute to the effectiveness of investigating food-borne outbreaks and thus to the prevention of related cases.
  • Kirje
    Welfare of livestock sheep transport in hot and cold climates
    (Estonian University of Life Sciences, 2022) Carnovale, Francesca; Arney, David; Aland, Andres; Napolitano, Fabio; Institute of Veterinary Medicine and Animal Sciences; Dwyer, Cathy (opponent)
    Animal transportation, which is increasing due to higher demand for meat and the centralisation of slaughterhouses, and climate changes are challenging for the animal husbandry sector and can have negative effects on animal health and welfare. The present thesis is the summary of research work carried out in Australia and Inner Mongolia (China), focusing mainly on the transport of sheep in different conditions and climates, and on public opinions on animal welfare. The importance of animals´ welfare during their transport is a critical problem that, if addressed, may reduce mortality and injury during transport and avoid economic losses. Climate change, which affects the animals´ environment, may lead to a higher risk of stress and mortality rates during animal transport. It is fundamental to determine if the current minimum standards for livestock transportation are still adequate. One of the world’s longest sea transport routes of live sheep for slaughter is from Australia to the Middle East. As shown in the results, heat stress is a major cause of mortality in shipments of sheep, particularly in sheep leaving Australia in the Southern Hemisphere winter to arrive in the Middle Eastern summer, and from this work it is suggested that shipments offloading at multiple ports should not offload at the hottest port, Doha, first. Following this work, the Australian Government changed its regulations regarding the transport of animals by sea. Cold stress can also have an impact on sheep wellbeing, thus it is important to establish if alternative truck designs and different transport methods can affect and improve sheep welfare during their transportation in cold temperatures. The sheep most at risk of the adverse effects of cold temperatures were found to be those that were transported in open vehicles, those transported for a longer time, and those that were not fed before transport. Understanding and public opinion have always helped to improve regulations and laws in general. In China, few studies have been carried out on public opinion on animal welfare. This study can improve the concept of animal welfare in China and help establish laws and guidelines on animal welfare during transport. It is concluded that animal welfare is of importance to the Chinese consumer, in particular because of its connection to food quality.
  • Kirje
    Changes in acute-phase proteins’ concentrations of neonatal ruminants in relation to colostrum and weight gain
    (Estonian University of Life Sciences, 2022) Peetsalu, Kristel; Orro, Toomas; Tummeleht, Lea; Institute of Veterinary Medicine and Animal Sciences; Sauerwein, Helga (opponent)
    Intensive farming has often led to increased spreading of pathogens in herds. After birth, neonatal ruminants are vulnerable to potential pathogens, as the syndesmochorial type of placentation prevents the transfer of antibodies from mother to foetus. Therefore, the vital immune protection will be obtained by passive immune transfer from colostrum. Colostrum contains various bioactive components, e.g. pro-inflammatory cytokines and acute-phase proteins, the effect of which on offspring is the focus of this research. A major role in protection against pathogens is played by the newborn ruminant's innate immune system, part of which is acute-phase reaction, during which the acute phase proteins are synthesised, mainly in the liver. Acute-phase proteins are used as quantitative sensitive inflammatory markers in medicine. In this thesis, the acute phase reaction during the neonatal period of reindeer calves, lambs and dairy calves was investigated by evaluating the acute phase proteins (serum amyloid A, haptoglobin, albumin, fibrinogen). Additionally, the influence of colostrum acute-phase proteins on the neonatal ruminants' acute phase reaction was evaluated. To identify the possible long-term effect of acute phase reaction in the neonatal period, the average daily weight gain in the 3, 4 and in 9 months was measured. During the neonatal period, there is a fluctuation in acute-phase proteins concentration, which is the lowest on the day of birth. The acute phase reaction on the first living week is influenced by colostrum acute phase proteins and pro-inflammatory cytokines. The acute phase reaction on the second and third week of life has a long-term influence on the animal’s growth. Knowledge of the early immunological development of a newborn ruminant allow providing a better growth environment, which means better welfare and preventing the spread of pathogens in intensive farming systems.
  • Kirje
    Polyphenolic composition of rhubarb (Rheum rhaponticum L.) and blackcurrant (Ribes nigrum L.), antibacterial and free radical scavenging properties of these plants in comparison with some other food plants
    (Eesti Maaülikool, 2021) Raudsepp, Piret; Püssa, Tõnu; Kikas, Ave; Yang, Baoru (opponent)
    Antibacterial and antioxidative compounds are used in food processing to extend shelf life. Consumers are increasingly demanding these compounds to be as natural as possible. Polyphenols are a very diverse group of compounds found in plants, comprising molecules with both antibacterial and antioxidative properties. In the present study, the polyphenolic composition of blackcurrant berries and leaves and rhubarb petioles and roots were investigated by means of liquid chromatography-UV-Vis detector, coupled with ion trap mass detector and comparing the obtained results with scientific literature data. The antibacterial activity and free radical scavenging ability (considered as an antioxidative activity) of extracts made from the same plant parts were compared with the effects of different food plants in two different experiments. Comparison included tomato fruits, bilberry, sea buckthorn, blue honeysuckle and chokeberry berries. It was found that the high content of polyphenols in the plant material does not yet make it possible to say whether the material has good antibacterial or antioxidant properties. These properties seem to depend on different polyphenolic and other compounds. For example, in rhubarb the high levels of polyphenols are due to anthraquinones and stilbenes, which are known to have relatively strong antibacterial properties but weak antioxidative properties. In the blue and red berries, most of the polyphenols are composed of anthocyanins, which have strong antioxidative but weak antibacterial properties. In addition, berries contain vitamin C, which also has an antioxidative effect. By combining different food plants and adding them to other foods, it is possible to achieve both antibacterial and antioxidative properties, while keeping in mind the food safety and sensory properties of the food. Among other results, it was found, that the tested plant extracts (in paper III) had stronger AB effect against B. subtilis, K. rhizophila, L. acidophilus, B. bifidum, L. monocytogenes, E. coli and C. jejuni than sodium nitrite solutions, nevertheless, none of the authors recommends substituting sodium nitrite in the processed meat products entirely with plant materials. Many more studies are needed before such recommendations can be made, especially taking into account hazards, related to bacterial species like Clostridium botulinum and other Clostridia. At the moment, such studies can not be conducted in Estonia. In the later works of our research group, we have used many of the above mentioned plant materials in meat products and achieved both antibacterial and antioxidative activities.
  • Kirje
    Взаймосвязь воспроизводительной способности и молочной продуктивности и ее использование в селекции молочного скота : автореферат диссертации на соискание ученой степени доктора сельскохозяйственных наук
    (Всесоюзный научно-исследовательский институт разведения и генетики сельскохозяйственных животны, 1985) Saveli, Olev
    Актуальность темы. Выполнение Продовольственной программы СССР является главной задачей народного хозяйства. Центральным Комитетом КПСС и Советом Министров СССР предусмотрены эффективные мероприятия по обеспечению населения продуктами питания. Основная роль при этом отводится научно-техническому прогрессу, т.е. интенсификации производства. В климатических условиях северо-западных районов СССР ведущей отраслью животноводства является молочное скотоводство. Наряду с молоком и молочными продуктами в Эстонской ССР производство говядины составляет 42,1 % от валовой продукции мяса. Выполнение задач XI пятилетки по производству молока и говядины решалось в республике главным образом путем интенсификации производства. Повышение удоя на фуражную корову с 3579 кг в 1980 году до 3855 кг в 1984 году и увеличение суточного прироста и живой массы у сдаваемого государству скота позволили эффективнее использовать кормовые ресурсы и интенсивнее капитальные вложения, повысить доходы хозяйств и рентабельность производства. Возрастающая потребность в пищевых продуктах и промышленном сырье требует дальнейшей интенсификации производства молока. Основные резервы кроются в улучшении племенных качеств пород крупного рогатого скота, в достижении ритмичного воспроизводства дойного стада и, конечно, в укреплении кормовой базы.
  • Kirje
    Типы трансферринов у крупного рогатого скота Эстонской черно-пестрой породы и возможности их использования в племенной работе : автореферат диссертации на соискание ученой степени кандидата сельскохозяйственных наук (550)
    (Эстонская сельскохозяйственная академия, 1968) Saveli, Olev
    Непрерывно возрастающие потребности населения выдвигают перед скотоводством очень серьезные задачи, разрешение которых зависит от улучшения условий внешней среды и наследственных качеств животных. Поскольку изменение условий внешней среды в большей степени зависит от сознательной деятельности людей, то эти проблемы исследованы относительно подробно. Выяснение наследственных предпосылок животных является более трудным вопросом. В настоящее время племенную ценность молодняка оценивают лишь на основе их предков. Однако наряду с такой оценкой необходимо непосредственно изучить генотип животного, на что и направлены исследования последних лет в области генетики и разведения сельскохозяйственных животных. Для получения информации о генотипе животного начали интенсивно исследовать некоторые биохимические показатели. Группы крови изучаются уже с начала XX столетия, исследование же белковых компонентов крови и молока достигало успеха лишь в последние годы. Благодаря электрофорезу на крахмальном геле, только у крупного рогатого скота было выявлено 14 генетически контролируемых систем белков. Зная типы разных белков, получают ценную информацию, характеризующую генотип животного.
  • Kirje
    Патоморфологические изменения, патоморфогенез и эпизоотология микобактериозов у свиней, вызываемых микобактериями комплекса avium-intracellulare : автореферат диссертации на соискание ученой степени доктора ветеринарных наук (16.00.02), (16.00.03)
    (Всесоюзный институт экспериментальной ветеринарии им. Я. Р. Коваленко; Всесоюзной академии сельскохозяйственных наук им. В. И. Ленина, 1983) Koslov, Nikolai
    XXVI съезд КПСС, выдвигая широкую программу социального развития и повышения народного благосостояния, на первый план поставил задачу улучшить снабжение населения продуктами питания. Для решения этой задачи разработана и одобрена майским пленумом ЦК КПСС (1982 г.) Продовольственная программа СССР на период до 1990 года, которая является важнейшей составной частью экономической стратегии партии на ближайшее десятилетие. Программой предусмотрено уделять больше внимания дальнейшему развитию свиноводства как наиболее скороспелой отрасли животноводства. Намечено обеспечить производство свинины (в убойном весе) в 1985 году в количестве не менее 6,5 млн. тонн и в 1990 году — 7—7,3 млн. тонн. Важную роль в успешном развитии свиноводства играют ветеринарные мероприятия, обеспечивающие благополучие в отношении инфекционных болезней. В связи с социальным и экономическим значением особое место среди инфекционных болезней занимает туберкулез — одна из главных антропозоонозных инфекций млекопитающих и птиц. Туберкулез свиней представляет опасность и для других видов сельскохозяйственных животных, а также для человека. Кроме того, при туберкулезе бракуется значительное количество туш и органов, что наносит экономический ущерб в результате недополучения продуктов свиноводства.
  • Kirje
    О патологических изменениях при аспергиллезе у гусей и некоторые вопросы этиологии, патогенеза и клиники этого заболевания в Эстонской ССР : автореферат диссертации на соискание ученой степени кандидата биологических наук
    (Академия наук Эстонской ССР, 1962) Koslov, Nikolai
    В директивах КПСС и Советского правительства неоднократно обращалось внимание на необходимость ускорения темпов повышения животноводческой продукции, причем подчеркивалось, что быстрое увеличение мясных ресурсов в нашей стране в настоящее время в значительной мере зависит от успешного развития свиноводства и птицеводства. Мартовский Пленум Центрального Комитета КПСС в борьбе за увеличение производства мяса поставил задачу взять новые высокие рубежи. В ближайшие годы, т. е. на первом этапе, задача состоит в том, чтобы производить 75 центнеров мяса на сто гектаров пашни и 16 центнеров на сто гектаров других угодий. На втором этапе необходимо производить 100 центнеров и на третьем этапе — 150 центнеров мяса на 100 гектаров пашни. В ходе выполнения этой задачи должно внести свой вклад и птицеводство, в том числе и разведение водоплавающей птицы. Для обеспечения успешного развития птицеводства особое внимание надо уделять предотвращению инвазионных и инфекционных заболеваний, причиняющих птицеводству значительный ущерб, выражающийся, с одной стороны, в гибели молодняка, а с другой — в снижении количества и качества птицеводческой продукции. К числу таких инфекционных заболеваний, приносящих птицеводству большой экономический ущерб, относится и аспергиллез.
  • Kirje
    Диагностирование, профилактика и лечение маститов у коров в молочных комплексах : автореферат диссертации на соискание ученой степени кандидата ветеринарных наук (16.00.03; 16.00.07)
    (Эстонская сельскохозяйственная академия, 1989) Klaassen, Mait
    Актуальность темы. Вопросы выполнения "Продовольственной программы СССР на период до 1990 года" рассматривались ХХVII съездом КПСС, наметившим дальнейшие пути развития сельского хозяйства и переход животноводства на промышленную основу. В 1980 году в Советском Союзе было построено 2120 крупных молочных комплексов (из них в Эстонской ССР – 273), производящие 50% молока от общей молочной продукции страны (Е. Valdmann et al., 1980). Однако при концентрированном содержании молочного скота повышается опасность возникновения и распространения болезней животных с инфекционной этиологией, в том числе маститов. Снижение заболеваемости коров маститами является проблемой, решением которой занимаются ученые многих стран. По данным отечественных и зарубежных авторов маститы в большинстве случаев протекают субклинически (0. W. Schalm et al., 1971; Я. А. Ветра с cоавт., 1974; В. М. Карташова, Т. Н. Самоловова, 1975; А. Н. Голиков, Е. И. Любимов, 1977; Е. П. Карманова с соавт., 1979; Т. R. Batra, 1980; С. Б. Брейтерман, 1981; В. Cagienar, 1983; Г. В. Зверева с сoавт,, 1985 и др.), при этом молочная продуктивность больных коров снижается в среднем на 400-500 кг в год и ухудшается качество молока. Поэтому усовершенствование методов диагностики, профилактики субклинических маститов и лечения больных коров является весьма актуальным вопросом уже в течение нескольких десятилетий (И. Н. Афанасьев, 1959; Н. Г. Шатохин, 1969; В. И. Хоменко, 1974; М. П. Рязанский, B. В. Воронкина, 1977; В. М. Воскобойников, Б. С. Спиридонов, 1979; К. А. Петерсон с соавт., 1979; И. С. Загаевский, 1979; Е. П. Кремлев, 1982; Д. Л. Логвинов, Н. Д. Вольвач, 1982; Н, К. Оксамитный, 1982; В. А. Париков с соавт., 1982; Г. А. Черемисинов, А. С. Лободин, 1982; Н. И. Полянцев, А. Н. Синавин, 1985; А. П. Студенцов, В. С. Шапилов, Л. Г. Субботина, 0. Н. Преображенский, 1986 и др.).
  • Kirje
    Эймериоз крупного рогатого скота на фермах Эстонской ССР (эпизоотология, влияние на организм хозяина, профилактика) : автореферат на соискание ученой степени кандидата ветеринарных наук
    (Белорусский научный исследовательский институт экспериментальной ветеринарии, 1987) Karis, Alar
    Актуальность работы. Директивами ХХVII съезда КПСС по двенадцатому пятилетнему плану развития народного хозяйства СССР, а также решениями майского (1982 г.) Пленума ЦК КПСС, на котором была принята Продовольственная программа до 1990 года, предусматривается увеличение производства сельскохозяйственных продуктов, в том числе животноводческих. Одним из путей решения этой задачи является усиление внимания к различным паразитарным заболеваниям, препятствующим повышению продуктивности животных. В этой связи особое место занимает эймериоз крупного рогатого скота. Эймерии и эймериоз крупного рогатого скота широко распространены во всем мире (D.Romeyke, 1977; C.Cotteler, L.Famerce, 1978; O.Majoro, 1980; O.M.Radostis, P.G.Stockdale, 1980; R. Parker, 1981; I.Pavlasek, 1982; H.-J.Burger, 1983; P.Yvore et al., 1983 и др.) и в различных зонах Советского Союза (Т.В.Арнастаускене, 1964; В.Р.Гобзем, 1964; H.М.Лапшин и соавт.,1980; Н.Н.Евплов, 1982; О.Чарыев, Г.Бегмурадов, 1977; С.Г.Манафова, 1972; А.Л.Рашидов, В.И.Елагин, 1981 и др.). Работ, посвяшенных изучению распространения эймериоза крупного рогатого скота в Эстонской ССР, мало (J.Parre, J.Praks, 1975). Концентрация животноводства создала новые экологические условия, определяющие эпизоотологию эймериоза однако исследования по этому вопросу в условиях республики отсутствуют. Несмотря на то, что эймериозы приносят значительные убытки животноводству (L.Niilo, 1970; P.R.Fitzgerald, 1980; Н.Н.Евплов, 1982), вопросы о патогенности эймерий крупного рогатого скота до сих пор полностью не решены. В настоящее время многими исследователями (P.R.Fitzgerald, М.К.Mansfield, 1973; Н.A.Alfonso et al., 1982; 1978; K.Henker et al., 1979; П.Йуркович и соавт., 1979; Н.Н.Евплов, Ю.Т.Андрюшин, 1980; А.П.Коломацкий и соавт., 1982 и др.) испытано большое количество различных препаратов, но данные об их эффективности весьма разноречивы.
  • Kirje
    Relationships between body condition, lipomobilization and insulin resistance in dairy cows
    (Eesti Maaülikool, 2021) Karis, Priit; Jaakson, Hanno; Ling, Katri; Ots, Meelis; Kokkonen, Tuomo (opponent)
    The first weeks of lactation are the most demanding period for the metabolism throughout the calving cycle of a dairy cow. Most of the disease events occur during that period; this highlights the need for deeper understanding of cows’ adaption to lactation to increase the welfare of cows and profitability of farm. Insulin is a pancreatic hormone that has a key role in energy metabolism, in general, it promotes storage of energy within organism. Insulin resistance is a state when insulin causes less than normal response in target tissues. It causes intensive lipolysis, which is a risk factor for the occurrence of numerous metabolic diseases. This doctoral thesis elaborates on the relationships of the volume of adipose tissue during dry period with lipolysis, insulin resistance, and the expression of genes and concentration of proteins in adipose tissue that regulate glucose and lipid metabolism. Four weeks before expected calving multiparous Estonian Holstein dairy cows (n=42) were grouped into three according to their body condition score. Three weeks before and after calving intravenous glucose tolerance test and biopsy from subcutaneous adipose tissue were performed. After the formation of experimental groups, blood samples were taken weekly and body condition was assessed fortnightly. Milk samples were taken and zootechnical data registered until the end of the lactation. The energy corrected milk production of over-conditioned cows was higher than that of optimal or thin cows, but the higher production was achieved at the expense of intensive use of energy stored in adipose tissue. Cows that were more resistant to insulin action before calving were prone to intensive lipolysis at the beginning of lactation, which was related to lower expression of lipogenic genes and lower concentration of glucose transporter 4 in subcutaneous adipose tissue. Results clearly show that excessive volume of adipose tissue increases metabolic load and the risk of metabolic diseases. Monitoring body condition of dairy cows gives an opportunity to assess the feeding level on the farm and to avoid overconditioning.