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3. Doktoritööd

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

Sirvi

Sirvi 3. Doktoritööd Pealkiri järgi

Nüüd näidatakse 1 - 20 57
  • Pisipilt
    Kirje
    Alterations of Epidermal Cells Functional Activity in Fish Due to Infection
    (Eesti Maaülikool, 2012) Päkk, Priit; Paaver, Tiit; Hussar, Piret
    Previous results have suggested that epidermal club cells have a generic role in response to injury and that they display intense phagocytic activity, having an anti-parasitic function in the host. The presently reported doctoral theses focused on the alterations of epidermal club cell activity and on the integration with mucous cells in common carp epidermis by ichthyophthiriosis and mucus production in triploid Atlantic salmon by gyrodactylosis also elucidate processes involved in epidermal papillomatosis regeneration of koi carp which occurs during a steady temperature increase. The results of this thesis demonstrate the potential role of club cells in healing process during and after damages in carp, but not anti-parasite functions of these cells. For better understanding of club and mucous cells integrated functions further studies should conduct more extensive sampling from all parts of the freshwater fish.
  • Pisipilt
    Kirje
    Antimicrobial Resistance of Escherichia Coli and Enterococci Isolated From Swine, Cattle and Dogs and Mastitis Pathogens Isolates in Estonia in 2006-2015
    (Eesti Maaülikool, 2019) Aasmäe, Birgit; Kalmus, Piret; Orro, Toomas; Nilsson, Oskar (opponent)
    Antimicrobial resistance has been a global emerging threat in both human and veterinary medicine during last two decades. Antimicrobial resistance as a global problem needs to be handled on national, regional and international levels as a “One Health” approach with involvement of professionals in human and veterinary medicine. This broad-based overview of antimicrobial resistance of animal (swine, cattle and dogs) bacteria isolated in Estonia creates a basis for the future investigations and analyses of the resistance development in Estonia. The prevalence of acquired antimicrobial resistance both in commensal bacteria of the enteric microflora of healthy animals (swine and cattle) and animal pathogens indirectly indicates the magnitude of the selective pressure from the use of antimicrobials in animal populations. In light of this, we strongly recommend assessment of the treatment plans in the swine industry in Estonia in order to ensure the prudent use of antimicrobials and to minimise the potential spread of resistant bacteria from swine to the environment and to humans. The use of antimicrobials in cattle in Estonia should be reviewed. Appropriate guidelines for antibiotic usage were first published in 2012, while completed guidelines for antimicrobial treatment of different animal species were published and implemented in 2018. A system for effective control of the use of antibiotics in veterinary medicine in Estonia is still needed.
  • Pisipilt
    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.
  • Pisipilt
    Kirje
    Bacillus smithii TBMI12 as a potential probiotic feed additive
    (Eesti Maaülikool, 2014) Suitso, Indrek; Nurk, Allan; Viltrop, Arvo
    The purpose of the thesis was to investigate the potential of Bacillus smithii strain TBMI12 as a probiotic feed additive. For that safety, colonization, tolerance and challenge studies were performed with mice and pigs. Experiments showed that this strain is able to colonize gastrointestinal tract without harming the host or causing significant changes in the microbiota or disrupting the biodiversity of the gastrointestinal tract. Also colonization of the gastrointestinal tract with the Bacillus smithii TBMI12 endospores decreased the probability of Salmonella Enteritidis infection and decelerated the process of pathogenesis. Based on the results this strain has a potential to be probiotic feed additive.
  • Pisipilt
    Kirje
    Campylobacter spp. and Listeria monocytogenes in poultry products in Estonia
    (Eesti Maaülikool, 2016) Praakle, Kristi; Roasto, Mati; Hänninen, Marja-Liisa; Korkeala, Hannu
    Campylobacteriosis, caused by thermotolerant Campylobacter species, is continued to be one of the most commonly reported zoonosis in humans in the European Union, and Campylobacter is recognized as the most common causative agents of bacterial gastroenteritis in developed world. Listeriosis, the disease caused by Listeria monocytogenes, is a lifethreatening disease for individuals with compromised immune systems. Consumption of different foods, including poultry products, have been associated with campylobacteriosis and listeriosis. Healthy birds may shed Campylobacter spp. and L. monocytogenes in fecal material asymptomatically. Poultry meat may become contaminated with fecal matter during slaughter or through cross-contamination during processing. The main goals of the present thesis were 1) to determine the prevalence and counts of Campylobacter spp. and the prevalence of L. monocytogenes in Estonian and imported raw poultry meat, 2) to serotype and genotype using pulsed-field gel electrophoresis both Campylobacter and L. monocytogenes isolates, and 3) to determine the antimicrobial susceptibility of the Campylobacter isolates. The studies showed that the poultry products of Estonian origin and imported to Estonia were contaminated with Campylobacter spp. and L. monocytogenes. There was high sero- and genotype diversity among Campylobacter and L. monocytogenes isolates. High level of resistance to fluoroquinolones, tetracycline, ampicillin, and erythromycin among the Campylobacter isolates were detected.
  • Pisipilt
    Kirje
    Campylobacter spp. in Estonian Broiler Chicken Production Chain and the Co Effect of Pro- and Prebiotics on the Campylobacter spp. Strains in vitro
    (Eesti Maaülikool, 2010) Meremäe, Kadrin; Elias, Priit; Roasto, Mati; Hänninen, Marja-Liisa
    Termofiilsed kampülobakterid on sagedased akuutse gastroenteriidi tekitajad inimestel. Kampülobakterenteriiti haigestumise peamisteks põhjusteks on ebapiisavalt kuumtöödeldud või kuumtöötluse järgselt kampülobakteritega saastunud broileriliha tarbimine. Seepärast võib Campylobacter spp. laialdane levik broileriliha tootmise ahelas kujutada tõsist ohtu tarbija tervisele. Viimastel aastatel on esile tõusnud ka Campylobacter spp. antibiootikumidele resistentsuse probleem, kuna on avastatud kampülobakterite multiresistentseid tüvesid nii veterinaarmeditsiinis kui humaanmeditsiinis isoleeritud tüvede seas. Arvestada tuleb sellega, et antibiootikumidele resistentsete tüvede poolt põhjustatud kampülobakterenteriit ei pruugi alluda tõsisemate vaevuste korral vajalikuks osutunud antibiootikumravile. Seepärast on oluline teaduslike baasuuringute raames välja selgitada pro- ja prebiootikumide võimalused pärssimaks antibiootikumidele tundlikke ja resistentsete Campylobacter spp. isolaatide elutegevust in vitro. Probiootikumideks nimetatakse inimese soolestikust isoleeritud eluvõimelisi mittepatogeenseid baktereid, mis omavad kliiniliselt tõestatud kasulikku toimet peremeesorganismile. Prebiootikumidena tuntakse lisandeid, mida ei lagundata maos ja peensooles, kuid on sobivaks toitaineks probiootilistele bakteritele nii organismi jämesooles kui ka probiootikume sisaldavates toiduainetes. Käesolevas töös uuriti aastatel 2002-2007 Campylobacter spp. levikut farmi, tapamaja ja jaemüügi tasandil, et saada ülevaade Campylobacter spp. kontaminatsiooni ulatusest broileriliha tootmise ahelas Eestis (uuring I). Töö raames määrati aastatel 2005 2006 isoleeritud Campylobacter spp. tüvede resistentsus antibiootikumide suhtes, et hinnata probleemi tõsidust Eestis (uuring II). Töös uuriti ka probiootiliste bakterite testtüvede (kombinatsioonis 1% oligofruktoosi või 1% inuliiniga ja prebiootikumideta) mõju antibiootikumidele tundlike ja resistentsete C. jejuni isolaatidele in vitro, et hinnata probiootikumide antimikroobseid omadusi nii broileriliha kui ka inimese väljaheite proovidest isoleeritud kampülobakterite suhtes (uuringud III, IV). Mueller Hintoni puljongites määrati probiootikumide poolt produtseeritud orgaaniliste hapete kontsentratsioon ning kasvukeskkonna pH, et välja selgitada orgaaniliste hapete sisalduse, pH muutuse ja C. jejuni arvukuse vahelised seosed. Töö käigus uuriti ka prebiootikumide mõju probiootikumide eluvõimelisusele ja aktiivsusele, et hinnata nende koosmõju erinevates kasvukeskkondades, ning välja töötada sobivad kombinatsioonid C. jejuni valitud tüvede elutegevuse pärssimiseks in vitro (uuringud III, IV). Uurimistöös jõuti järgmiste tulemuste ja järeldusteni. Campylobacter spp. isoleeriti 163 (12.3%) Eesti päritolu broileriliha proovist jaemüügi tasandil ja 115 (6.3%) umbsoolesisuproovist tapamaja tasandil. Farmi tasandil osutusid kõik 1254 värsket roojaproovi Campylobacter spp. suhtes negatiivseks. Järelikult oli Campylobacter spp. kontaminatsioon Eestis kõikidel broileriliha tootmise tasanditel madal võrreldes samalaadsete uuringute tulemustega Euroopa Liidus. Uurimistulemused näitasid, et Eesti broileriliha tootmise ahelas esineb Campylobacter spp. levikus kõrghooaeg juulist septembrini. Campylobacter spp. liigiline identifitseerimine näitas, et C. jejuni (98.2%) oli Eesti broileriliha tootmise ahelas kõige enam isoleeritud liik, millele järgnesid C. coli (1.4%) ja C. lari (0.4%). Uurimistulemustest selgus, et aastatel 2005-2006 osutusid 104 (79.4%) C. jejuni isolaati resistentseks ühe või enama testitud antibiootikumi suhtes. Järelikult tuleks jätkata isoleeritud Campylobacter spp. tüvede tundlikkuse määramist antibiootikumidele ning võtta kasutusele täiendavad meetmed, et minimeerida või vältida veel ulatuslikumat antibiootikumidele resistentsete C. jejuni isolaatide teket ja levikut. Saadud tulemused näitasid, et 27.5% isoleeritud C. jejuni tüvedest olid multiresistentsed, kusjuures kõik isolaadid olid resistentsed enrofloksatsiinile. Antud tulemus on murettekitav, sest multiresistentsuse kõrge näitaja Campylobacter spp. isolaatide seas oli antud uuringute põhjal üks kõrgemaid võrreldes samalaadsete uuringute tulemustega Euroopa Liidus. In vitro segatud bakterkultuuride katsed näitasid, et L. acidophilus ATCC 4356 kombinatsioonis 1% inuliini või 1% oligofruktoosiga ning B. bifidum Bb12 ja B. longum B46 kombinatsioonis 1% oligofruktoosiga inhibeerisid täielikult kõikide testitud C. jejuni isolaatide elutegevuse. Probiootikumide toime oli samalaadne (P > 0.05) nii neile testitud C. jejuni tüvedele, mis isoleeriti kas broilerilihalt või inimese väljaheitest, kui ka neile, mis olid tundlikud või resistentsed uuritud antibiootikumidele. Järelikult probiootiliste bakterite antimikroobne aktiivsus C. jejuni suhtes sõltus eelkõige probiootikumi liigist ja lisatud prebiootikumist, mitte aga C. jejuni tüvest. Saadud in vitro tulemused annavad alust arvata, et valitud probiootikumide antimikroobne aktiivsus kombinatsioonis sobiva 1% prebiootikumiga kõikide testitud C. jejuni suhtes on põhjendatav probiootikumide poolt intensiivse orgaaniliste hapete produtseerimisega, mille tagajärjel kasvukeskkonna pH vähenes kampülobakterite elutegevust pärssivale tasemele, vahemikuni 4.28-4.69. Uurimistulemustest selgus, et prebiootikumide tõhusus probiootikumide eluvõime ja aktiivsuse mõjutamisel sõltus kõige enam selle kontsentratsioonist kasvukeskkonnas. Majanduslikel kaalutlustel ja prebiootiliste lisandite efektiivsuse olemasolu tõttu osutus optimaalseks koguseks 1% (kg/l). Prebiootikumidest suurendasid probiootikumide aktiivsust ning arvukust eelkõige oligofruktoos ja seejärel inuliin. Järelikult antud prebiootikumid koostoimes valitud probiootikumidega osutusid sobilikuks inhibeerimaks C. jejuni arvukust ja elutegevust in vitro.
  • Pisipilt
    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.
  • Pisipilt
    Kirje
    Campylobacter spp. in Poultry and Raw Poultry Meat Products in Estonia With Special Reference to Subtyping and Antimicrobial Susceptibility
    (Eesti Maaülikool, 2008) Roasto, Mati; Hänninen, Marja-Liisa; Hörman, Ari; Elias, Priit; Olsson Engvall, Eva
    Kampülobakterid on üle maailma levinud nii loomade kui inimeste populatsioonis. Kuigi patogeeni ülekande teatud aspektid on seniajani teadmata, on toimunud suur edasiminek nende reservuaaride ja infektsiooni üldise leviku välja selgitamisel. Zoonooside ehk loomadelt inimestele ülekanduvate haiguste uurimine on oluline mitte ainult nende ohtlikkuse ja sageda esinemise tõttu, vaid ka seepärast, et nad on sageli ettearvamatud ning raskesti diagnoositavad. Eelnev kehtib nii kampülobakterite kui ka teiste zoonootiliste patogeenide suhtes. Perekonna Campylobacter mitmed liigid on sageli mets- ja koduloomade (veised, lambad, sead, kitsed, närilised, kassid, koerad ja linnud)maosooletrakti kommensaalideks. Mitmed uuringud on näidanud, et inimestel põhjustavad haigestumist eelkõige loomsetest reservuaaridest pärinevad bakterid. Enamik kampülobakteritest põhjustatud haigustest tekib sporaadiliselt ja nakatumise taust ei ole sageli teada. Nakkusallikateks peetakse tavaliselt linnuliha, toorest või alaküpsetatud liha, pastöriseerimata piimatooteid ning kuumtöötlemata toite, kui on toimunud saastumine töötlemisprotsessis. Toorpiim on samuti sagedane haigestumise põhjustaja. Kampülobakterite probleemi lahendamiseks on olemas nii kohesed kui ka pikemaajalised vastumeetmed. Kohestest meetmetest tuleb märkida pastöriseerimist, toiduainete korralikku läbiküpsetamist (sisetemperatuur tootes vähemalt 72 ºC) ning ristsaastumise vältimist igal tasandil. Toiduainete külmutamine vähendab oluliselt toodete kontaminatsiooniastet, kuid mõnede bakterite eluvõime võib püsida mitmeid kuid. Pikemaajalised meetmed hõlmavad tekitajate saastumisastme vähendamist koduloomade ja lindude seas; protseduuride väljatöötamist, mis hävitavad patogeeni enne toidu tarbijani jõudmist ning avalikkuse toiduhügieenialast teavitamist. Uurimistöö eesmärgid. Määrata Eestis müüdavate toorete linnulihatoodete sa 1. astatus termofiilsete kampülobakteritega, et selgitada linnuliha kui kampülobakterite potentsiaalse siirutaja roll inimesele (I, II, III). 2. Kampülobakterioosialaste epidemioloogiliste uuringute täiendamiseks ning termofiilsete kampülobakterite sero- ja genotüüpilise jaotumuse ning diversiteedi mõistmiseks teostada isoleeritud kampülobakterite tüvede sero- ja genotüpiseerimine (II). 3. Määrata isoleeritud kampülobakterite tüvede tundlikkus antibiootikumidele, et saadud tulemusi võrrelda teiste Euroopa Liidu maadega, saada selgust probleemi tõsidusest Eestis ja pakkuda välja võimalusi probleemide lahendamiseks (II; III). Uurimistöö materjal ja metoodika. Uuritavaks materjaliks olid põhiliselt nii Eestis toodetud, kui Eestisse imporditud toored linnuliha tooted. 1. Eesti väikese võimsusega ettevõtte linnuliha toodang oli võrreldes suure võimsusega ettevõtte toodanguga oluliselt (P < 0,001) rohkem kampülobakteritega saastunud. Lindude rümbad ja tiivatükid (vastavalt 28% ja 31.3%) olid oluliselt (P < 0,001) sagedamini saastunud, võrreldes rinna- ja kintsutükkidega (0% ja 0%). Eesti päritolu jahutatud linnulihatoodete saastumine termofiilsete kampülobakteritega oli 9,1% kusjuures külmutatud impordtoodetel ulatus see näitaja 15,9%-ni. Imporditud linnuliha kõrgem saastumine võis olla tingitud algtootmise kõrgest kontaminatsioonist termofiilsete kampülobakteritega. Võrreldes Tallinnast kogutud proovidega osutusid Tartu turgudel võetud linnuliha proovid oluliselt rohkem saastunuteks termofiilsete kampülobakteritega. Selline oluline erinevus võis olla tingitud proovide laboratooriumisse toimetamise erinevatest transpordiaegadest. Tartust võetud proovid toimetati analüüside teostamiseks laboratooriumi praktiliselt kohe pärast proovide võtmist, kuid Tallinnast võetud proovid analüüsiti Helsingi Ülikooli Toidu- ja Keskkonnahügieeni laboris, mis tähendas mitmete tundide võrra pikemat aega analüüsi alguseni. Hooajaliselt isoleeriti Eestis müüdud tooretelt linnulihatoodetelt termofiilseid kampülobaktereid kõige sagedamini juunist kuni novembrini. Meie termofiilsete kampülobakterite uuringud, mis sellises ulatuses olid Eesti veterinaarmeditsiinis esimesed, peavad jätkuma, et täiendavate uuringutega selgitada välja Campylobacter spp. levimust ja esinemissagedust põllumajandusloomade karjade tasandil. Uuringute jätkumine on vajalik ka edasiste Campylobacter spp. kontaminatsiooni suundumuste välja selgitamisel. 2. Uuringutest saadud tulemused osutasid toiduainetest isoleeritud kampülobakterite tüvede sero- ja genotüüpilisele mitmekesisusele. Olulist seost serotüüpilise jaotumuse ja proovide päritolu vahel antud uuringutes ei leitud. Seitsmekümne Campylobacter ’i isolaadi genotüpiseerimine näitas, et restriktsiooniensüüm KpnI on võrreldes SmaI-ga suurema genotüüpide eraldamisvõimega. Nimelt, andis restriktsiooniensüüm KpnI meie uuringutes 34 PFGE tüüpi võrreldes SmaI restriktsiooniensüümi 29 genotüübiga. PFGE analüüs KpnI ja SmaI ensüümidega tõestas head kampülobakterite isolaatide tüpiseerimise ning katsete korratavuse võimet. Selge seos oli genotüüpilise jaotumuse ja proovide päritolu vahel, kuid genotüüpide ja geograafilise piirkonna seotus vajab ulatuslikemaid uuringuid. 3. Antud uurimuse tulemused näitasid toiduainetest isoleeritud kampülobakterite tüvede kõrget resistentsust praktiliselt kõikide uuringus kasutatud antimkroobsete ühendite suhtes. Kõrged minimaalsed inhibeerivad kontsentratsioonid (MIK) makroliidide ja fluorokinoloonide suhtes osutavad tõenäoliselt võimalikele tervishoiualastele probleemidele tingituna asjaolust, et erütromütsiin ja teatud fluorokinoloonid on inimeste kampülobakteritest põhjustatud infektsioonide ravis esimesteks valikpreparaatideks. Teostatud uuringute tulemuste eriti murettekitavaks faktiks tuleb aga pidada multiresistentsete kampülobakterite tüvede kõrget arvu, 36 isolaati ehk 27,5% isoleeritud kampülobakterite tüvedest, osutus multiresistentseks. Aastatel 2005 ja 2006 toimunud uuringud osutasid selgelt faktile,et fl uorokinoloonide kasutamine võib esile kutsuda multiresistentsete tüvede tekke. Campylobacter spp. antibiootikumidele tundlikkuse uuringud peavad jätkuma, et selgitada välja resistentsuse suundumusi ning seonduvaid resistentsusmehhanisme ja võimalusi termofi ilsete kampülobakterite resistentsuse/multiresistentsuse vähendamiseks Eestis.
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    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.
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    Kirje
    Clinical mastitis in Estonia: diagnosis, treatment efficacy and antimicrobial resistance of pathogens in Estonia
    (Eesti Maaülikool, 2014) Kalmus, Piret; Orro, Toomas; Kask, Kalle
    Mastitis is a most common bovine disease, causing a large economic impact on dairy industry, due to increased treatment cost, decreased milk quality and unnecessary culling of dairy cows. The primary objective of present research was to evaluate clinical mastitis pathogens, antimicrobial resistance and treatment efficacy in Estonian dairy cows. The second objective was to find association between local inflammatory reaction in the udder and bacteriological diagnosis of clinical mastitis using PCR-based method. The clinical mastitis udder pathogens and risk factors in primiparous and multiparous dairy cows were evaluated in eleven Estonian dairy herds. During one-year study period, the incidence rate of clinical mastitis at calving was 6.4% among 1053 primiparous dairy cows. The study showed that housing system was not a significant risk factor for clinical mastitis of freshly calved heifers. Moving heifers to the calving facilities too late increased risk for clinical mastitis at parturition in tie-stall farms. The isolated udder pathogens in heifers did not differ significantly in tie-stall farms compared to freestall farms, but differences were found between heifers and multiparous cows at parturition. To estimate the distribution of udder pathogens and their antibiotic resistance in Estonia during the years 2007-2009, 3058 clinical mastitis samples from 190 farms and 5146 subclinical mastitis samples from 274 farms were investigated. Streptococcus uberis was the bacterium isolated most frequently (18.4%) from cases of clinical mastitis, followed by E. coli (15.9%) and Streptococcus agalactiae (11.9%). The bacteria that caused subclinical mastitis were mainly Staphyloccus aureus (20%) and coagulase-negative staphylococci (15.4%). Antimicrobial resistance was highly prevalent. The proportion of Staphylococcus aureus and CNS isolates that were resistant to penicillin was 61.4% and 38.5%, respectively. Among the E. coli isolates, ampicillin, streptomycin and tetracycline resistance were observed in 24.3%, 15.6% and 13.5%, respectively. The quantity of bacterial DNA in milk samples was associated with concentrations of APP and NAGase activity in the milk. These indicators reflect the inflammatory reaction in the mammary gland, and their concentrations increased with increasing severity of mastitis. Concentrations of APP and NAGase activity in milk significantly differed between different mastitis-causing bacterial species. Milk amyloid A and Hp concentrations and NAGase activity were significantly higher in samples with large quantities of bacterial DNA from Escherichia coli or Streptococcus dysgalactiae compared with milk samples not containing those species. Milk samples containing Corynebacterium bovis and coagulase-negative staphylococci had significantly lower concentrations of MAA and Hp and lower NAGase activity compared with samples where these species were not detected. The efficacy of benzylpenicillin for the treatment of clinical mastitis (n=140) caused by Gram-positive bacteria susceptible to penicillin in vitro was not affected by the route of drug administration. Altogether, 80.3% of the quarters with systemic treatment and 74.7% of the quarters with IMM treatment exhibited a clinical cure, and 54.1% and 55.7% exhibited a bacteriological cure, respectively.
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    Comparative Morphology of European Elk and Cattle Pelves From the Perspective of Calving
    (Eesti Maaülikool, 2014) Nahkur, Esta; Jalakas, Mihkel; Ernits, Enn
    According to the anatomical literature, the osseous pelvis demarcates the pelvic cavity by the paired iliac, ischial, and pubic bones, as well as by the single sacral bone, as well as the first coccygeal vertebra. The findings of the present study show that, in addition to these bones, the elk and the EN cow have an interischial bone, which was previously described in the EHF breed. The latter plays a role in the attachment of muscles. In male animals it is necessary for the attachment of the penis. In female animals, this bone is involved in the fixation of the udder. The interischial bone is cartilaginous in young animals, but it ossifies with age and fuses together with the ischia. In the studied female animals the final ossification of the pelvic symphysis begins at the age of 5–6 years in the ischial symphysis and continues in the cranial part of the pubic symphysis. In all the studied pelves the space between the caudal branches of the pubes had not yet undergone ossification. Parts of the pelvis respond differently to sex hormones, and therefore the growth trajectories show sex- and species-related differences. Some structures of female pelves develop and ossify more quickly than others. Male animals develop longer although, for example, the cyclical nature of the lives of elk bulls slows down growth; however, in the case of favourable living conditions it enables them to grow larger. In the case of elks one cannot agree with the limit of the growth period determined on the basis of the jaw bones because the widening of the pelvic floor take place at the age of 6.5–7.5 years, and bulls experience additionally growth of the ilium and the sacral vertebrae. The shape of the pelvis in a female animal is conditioned mostly by lifestyle, fetal size, and the number of deliveries. Elk fetuses are small and the external measurements of the pelvis are rather narrow, which enables fast movement. The pelvic apertures are high and oval, and the width of the pelvic cavity is even throughout its length. The hip bones have a slanted position and the pelvic axis proceeds rather straight. The pelvic measurements and proportions largely complete their development by the first calving. It is possible to distinguish between the pelves of primiparous and pluriparous elks by the shape of the pubic symphysis, the pubic pecten, and the interischial bone, as well as the ossification of the tubers. Sexual dimorphism in adult elk pelves is more manifested in different configurations and in the case of the surface areas and transverse measurements of the pelvic apertures, which are considerably larger in female animals. The pelvic cavity of a bull is more longitudinal and tapers backwards. The pelves of adult elk bulls and cows can be distinguished by the shape of the pubic symphysis and the pubis, the size of the interischial bone, and the apophyses of its caudal branches. The pelvis of the EN cow shares some similarities with the pelvis of the medieval cow and the elk cow – it has small external measurements and is rather narrow. Suitability for calving is indicated by greater height of the pelvic apertures and an even diameter of the pelvic cavity, later ossification of the sacrum, and preserved mobility of the sacroiliac joint. Because in the EN cow the pelvic apertures quickly reach the possible full measurement, apparently earlier ossification of the pelvic symphysis does not pose a problem during calving. The sex-related difference in the pelvis is the largest in the pubic and ischial regions and becomes apparent with sexual maturity. The external absolute indicators of pelves of EHF bulls exceed those of cows; however, the latter are larger with regard to several internal measurements. More important age-related changes include replacement of cartilaginous tissue by osseous tissue in the acetabula up to ossification in the pelvic symphysis in an adult animal, order of ossification, fusion of the interischial bone with the hip bones. In the case of cows one should mention emergence of the cranial pubic tubercle, shifting of other pubic tubercles, and changes in the shape of the symphysial surfaces. The pelvic floor of medieval cows was similar to the pelvis of the elk cow as regards its gutter shape and caudodorsal widening, but the shape of the ischial tubers and the ilium were closer to the contemporary cow. Modern EHF cows have a large body and capacious digestive organs, which through abdominal muscles influence the strengthening of the prepubic tendon, the pubic pecten, and the symphysial crest. The pelvis is more adapted to carrying the udder and the internal organs; some new bony structures have emerged while mobility of limbs and suitability of the pelvis for calving have decreased. From the perspective of calving the pelvic apertures are too low, and a larger fetus may cause incompatibility between the fetus and the pelvis. For this reason, in cattle breeding and especially in the selection of bulls one has to take into account the height and evenness of the pelvic apertures of their mother and daughters, calving ability, and the birth mass of calves. The pelvis of the freely roaming elk has reached owing to natural selection and adaptation an optimum shape and position for living and procreation in its environment. The pelvis of the elk cow grants good mobility, support of the internal organs, udder attachment, and quick discharge during delivery. Humans have shaped the bovine pelvis by means of breeding and have caused a conflict between the different physiological functions of the pelvis. The specialized textbooks contain some statistical data about the bovine pelvis that need not be valid for modern animals because the breed and the time of measurements are unknown. The present study shows that the interischial bone occurs in addition to several ruminants; therefore, a proposal has to be made to include this term in the nomenclature of veterinary anatomy. At the same time it is necessary to check additionally whether this bone could exist in other animal species. Also, the nomenclature has to be supplemented with terms of the sub-parts by distinguishing between the cranial, lateral, and caudal tuberosities of the ischial tuber.
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    Contribution to the diagnosis and prognosis of canine cardiac disease through electrodiagnostics and diagnostic imaging
    (Eesti Maaülikool, 2020) Mõtsküla, Paul Fridtjof; Orro, Toomas; Fuentes, Virginia Luis; Connolly, David; Viitmaa, Ranno; Wess, Gerhard (opponent)
    Cardiomyopathy is defined as the heart muscle disease, leading to myocardial dysfunction. The World Health Organisation (WHO) classification includes dilated, hypertrophic, restrictive, arrhythmogenic right ventricular (ARVC) and unclassified cardiomyopathies. The study of cardiomyopathies in animals also contributes to a better understanding of the underlying pathophysiological processes and mechanisms of human cardiomyopathies. Cardiomyopathies account for a large proportion of overall morbidity and mortality in canine population with an estimated prevalence of 0.05%. The prevalence of dilated cardiomyopathy in certain dog breeds can be as high as 24-58%. ARVC has been described mainly in Boxer dogs, but the exact prevalence is not known due to the lack of definitive diagnostic criteria. The current study provides valuable prognostic information for the Boxer dogs with suspected ARVC that can be gained from 24-hour ambulatory electrocardiography (Holter monitoring) and from a single echocardiographic measurement that can be easily obtained during routine echocardiographic examination. A large difference between various dog breeds exists in prevalence and progression of different subtypes of cardiomyopathies. To investigate the extent of these differences, the prevalence of cardiac disease in another large dog breed with known predisposition to heart diseases, the Dogue de Bordeaux, was analysed. The previous information on the cardiac disease in this breed is mainly based on single case reports or small case series. The current study gives a broader overview of the heart diseases in this breed. Cardiac magnetic resonance tomography has a very important role in the diagnosis of human cardiomyopathies and the heart diseases in general but has not been widely used in veterinary medicine. The current study also contributes to the knowledge by a comparative analysis of the cardiac volumetric measurements acquired by echocardiography and magnetic resonance tomography.
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    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.
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    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.
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    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
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    Diagnosis, Epidemiology and Control of Bovine Coccidioses in Estonia
    (Eesti Maaülikool, 2009) Lassen, Brian
    Koktsiidid on ainuraksed parasiidid, kes tabandavad paljude imetajate soolerakke. Kõige tähtsamad veistel parasiteerivad koktsiidiliigid kuuluvad perekondadesse Eimeria ja Cryptosporidium. Need parasiidid põhjustavad eelkõige vasikatel ja noortel mullikatel sooleepiteeli rakkude hävimist, mis võib viia kliiniliste nähtude nagu näiteks diarröa tekkeni. Tihti haigustunnused puuduvad või on subkliinilised. Nakkus on iselimiteeruv, kuid selle patogeeni vastu immuunsuse omandamine sõltub nakkusdoosist ning loomade vanusest ja tervislikust seisundist. Koktsiidinakkus on harva letaalne, kuid pidurdab sageli loomade arengut. Aeglasem kaalu- iive võib põhjustada loomade vähenenud jõudlust. Koktsiidinakkusi uuriti Eestis 20 aastat tagasi ning ilma kvantitatiivseid andmeid esitamata. Piimakarjakasvatus on teinud vahepeal läbi tohutud muutused uute pidamissüsteemide kasutuselevõtu näol, mis võivad olla muutnud ka loomade invadeeritust parasiitidega. Käesolevas töös uuritakse koktsiidinakkuste praegust olukorda Eesti veisefarmides, antakse hinnang nakkust mõjutavatele faktoritele ja arvutatakse välja Eimeria nakkusega seotud kaod Eesti piimakarjafarmide jaoks. Uurimus sisaldab ka andmeid ühest autori poolt Leedus teostatud koktsidiooside uuringust piimakarja lehmadel ja kirjanduse ülevaadet parasiitsetest ainuraksetest koduloomadel Eestis. Uurimistöö jooksul koguti kõikide Eesti maakondade 45 piimakarjafarmist kokku 1050 roojaproovi. Loomad jagati kolme vanusegruppi: alla 3 kuu vanused (G0), 3-12 kuu vanused (G1), üle 12 kuu vanused loomad (G2). Koproproovid uuriti kvantitatiivse l otatsiooni meetodil Eimeria ja modii tseeritud Ziehl-Neelseni meetodil Cryptosporidium’i ootsüstide suhtes. Eimeria perekonna liigid määrati morfoloogiliste tunnuste alusel ja Cryptosporidium’i liigid lisaks ka geneetiliselt. Iga farmi juhatajat küsitleti parasiitide esinemise, pidamissüsteemi, veterinaar-sanitaarse hügieeni ja loomade ravimise kohta. Ootsüstide eritumist mõjutavaid faktoreid uuriti statistiliselt juhuslikele mõjudele allutatud multivariaabli segamudeli abil. Stohhastilisel mudelil simuleeriti Eimeria nakkusest põhjustatud toodangu kadusid 100-pealises Eesti katsekarjas kümne aasta jooksul. Statistiliselt tõesed koktsiidinakkused Eesti veisekarjades tehti kindlaks kõikides farmides, nende levimus farmiloomade hulgas ulatus 100%-ni. Vanusegruppides G0, G1 ja G2 esines Eimeria spp. vastavalt 35%, 63% ja 17% loomadest. Cryptosporidium spp. leiti samades vanusegruppides vastavalt 24%, 29% ja 37% loomadest. Veisekarjadest kogutud proovidest määrati kokku 12 erinevat Eimeria liiki: : E. bovis (30%), E. zuernii (22%), E. ellipsoidalis (14%), E. canadensis (13%), E. auburnensis (6%), E. subspherica (6%), E. alabamensis (3%), E. wyomingensis (3%), E. cylindrica (2%), E. brasiliensis (1%), E. pellita (1%), ja E. bukidnonensis (<1%). Esmaleidudeks Eestis olid järgmised liigid: Eimeria alabamensis, E. brasiliensis, E. bukidnonensis, E. canadensis, E. cylindrica ja E. wyomingensis. Ootsüstide genotüpiseerimisel identii tseeriti proovidest Cryptosporidium parvum and Cryptosporidium andersoni. Ühel inimese haigestumise juhtumil, kus nakkus saadi tõenäoliselt farmi külastamisel, identii tseeriti haigustekitajana samuti C. parvum. Kõhulahtisusega loomade arv oli positiives korrelatsioonis Cryptosporidiumi leiuga (semi- kvantitatiivne meetod) loomadel (regresiooni kordaja=0.07, p=0.05), aga Eimeria nakkuse puhul oli seos negatiivne (regresiooni kordaja= -0.08, p=0.01). Diarröad esines kõige rohkem grupis G1 ja see vähenes harilikult loomade vanemaks saades. Ootsüstide arv grammi rooja kohta vähenes koos loomade vanuse suurenemisega nii Cryptosporidium’i kui ka Eimeria puhul. Leedu farmides oli rohkem nii eimeeriatega kui ka krüptosporiididega nakatunud loomi. Võrreldes Eestiga, esines Leedus palju sagedamini E.alabamensis’t. Külastatud farmide juhatajatele esitatud küsimuste vastustest nähtub, et parasiitide vastaseid töötlusi tehakse harva ja enamasti kasutatakse selleks vaid insektitsiide. Teadmised parasitoloogiliste probleemide olemasolust ei olnud vastavuses tegelike parasitoloogiliste leidudega roojaproovidest. Kombineerides epidemioloogilisi faktoreid juhuslike mõjudega segamudelis leiti, et nii Eimeria kui Cryptosporidium’i ootsüstide eritumise võimalus suurenes, kui vasikad eemaldati koheselt pärast sündi emasloomade juurest. Võima lus ed Cryptosporidium’i ootsüstide eritumiseks vähenesid, kui karja suurus ületas 150 looma ja kui loomi peeti karjamaal. Alla 3-kuuste vasikate eraldi pidamisel vähenes Eimeria ootsüstide eritumine üle 12 kuu vanustel veistel. Eimeria ootsüstide eritumine üle 12 kuu vanuste veiste rühmas oli suurim sügisel. Eimeria ootsüstide eritumist suurendavateks faktoriteks samas veiste vanusegrupis olid niiskusesisaldus üle 75% ja vabanenud bokside taaskasutamine. Helmindid reeglina suurendasid Eimeria ootsüstide eritumist, samal ajal kui rühmades G0 ja G2 vähendas veiste herpesviiruse tüüp 1 ootsüstide eritumise võimalusi. Eimeeriatega nakatunud saja looma toodangu languse stohhastiline simulatsioon kolmes erinevas stsenaariumis andis tulemuseks farmeri tulu vähenemise 11%, 8% ja 2%. Need kolm stsenaariumi olid vastavalt: 1) halvim juhtum maksimaalsete Eimeria nakkuse mõjudega loomade arengule, koos suremusega; 2) juhtum praegu Eesti veisefarmides valitsevate hinnanguliste mõjudega; 3) parim juhtum kõige väiksemate võimalike mõjudega. Aeglasest kehakaalu langusest põhjustatud esimese seemenduse hilinemine mullikatel omas kõige tugevamat mõju toodangule ja majandusele. Surmajuhtumid ja aeglasem kaalu-iive olid väiksema tähtsusega. Koktsiide võib leida peaaegu igast Eesti farmist. Eimeria perekonna parasiidid nakatavad sageli 3-12 kuu vanuseid veiseid, kusjuures neil võib ilmneda diarröa. See vanusegrupp on nakkusele kõige vastuvõtlikum tänu võimalikule allasurutud või veel vähearenenud immuunsusele. Vanemad lehmad kannavad sageli nii Eimeria kui Cryptosporidium’i nakkust ja nende eraldamine noorloomadest (G1) aitab ära hoida vasikate nakatumist. Kui bokse ei puhastata, siis võimalused nakkuse levikuks suurenevad, hoolimata ajavahemik pikkusest, mil boksid seisavad tühjalt ning ootsüstid peaksid hävima. Vasikate jätmine emasloomade juurde mõjutab statistiliselt oluliselt Eimeria ootsüstide eritumist (ootsüstide arv on väiksem) Eesti piimakarjafarmides. Ei ole teada, kas seda põhjustavad immunoloogilised faktorid, keskkonnategurid või stressi puudumine, kuid igal juhul tasuks seda koktsidiooside tõrjemeetmeid planeerides arvesse võtta. Täiendavalt karja tabandavad patogeenid sekkuvad juba olemasolevasse nakkusesse ja mõjutavad samuti Eimeria ootsüstide eritumise intensiivsust. Parasiitidega nakatumise suurenemine või vähenemine võib mõjutada teisi patogeene nende vohamise või kadumise suunas ja vajalik oleks terviklik lähenemine probleemile. Sügis on suurima Eimeria-riski aeg ja võiks olla soovituslikuks kõrgendatud teadlikkuse perioodiks piimakarja pidavatele farmeritele. Diarröa ei osutunud käesoleva töö põhjal heaks koktsiidinakkuse indikaatoriks. Uuringute läbiviimise ajal ilmnes, et nii farmerite teadmised koktsiididest kui ka nende parasiitide tõrje Eesti piimakarjafarmides praktiliselt puudusid. Asja annaks palju parandada, kui farmereid koktsiidide olemasolust farmis ja nende tõvestavusest informeerida, tõstes loodetavasti need veiste patogeenid päevakorda. Otsustades nähtud pidamistingimuste põhjal, võiksid suhteliselt väikesed muudatused pakkuda farmerile aastasissetuleku tõusu 6-9% pikemaks ajaks. Käesoleval ajal on saadaval uued ravimid, mis annavad kiireid ja märgatavaid tulemusi. See lähenemisviis on adresseeritud sümptomite, kuid mitte probleemi enda likvideerimiseks. Suuremat kasu ja tulu annaks tõenäoliselt pidamistingimuste parandamine ja seda eriti noorloomade puhul. Koktsiidinakkuste tõrjeks on juba olemas teadmised, meetodid ja vahendid ning neid on vaja vaid rakendada. Kui on saavutatud teadlikkus, mõistmaks nakkuse mõju vähendamise kaudu saadavat kasu, algab ka muutus karjapidamise strateegias.
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    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.
  • Pisipilt
    Kirje
    Effect of crude glycerol feeding on feed intake, lactational performance and metabolic status of dairy cows
    (Eesti Maaülikool, 2014) Kass, Marko; Kärt, Olav; Arney, David
    Nowadays, the majority of glycerol, used as an essential primary good for the pharmaceutical, cosmetic, food and other industries, is becoming available as a byproduct from biodiesel manufacture. The rapid growth of the biodiesel industry has increased the availability of crude glycerol, and therefore its price has declined, making it more attractive amongst dairy farmers as a feed additive. Earlier studies have noted that feeding pure glycerol increases the propionate concentration in the rumen, and therefore its consideration as an efficient glucogenic substance for dairy cows after parturition. This thesis deals with some aspects of the use of unrefined glycerol originating from the biodiesel industry in dairy feeds, and discusses changes caused by its metabolism in the lactating dairy cow on several parameters, with special reference to Estonian feeding practices. In a study with post partum Holstein dairy cows the effects of oral drenching of crude glycerol on lactational performance and indices of negative energy balance were examined. Another aspect was to study the effects of replacement of barley meal with crude glycerol in mid-lactation Holstein dairy diets on the ruminal environment and nutrient degradability of grass silage in relation to feed intake and milk parameters, including milk renneting properties. The administration of 500 ml of crude glycerol for up to 21 days from the beginning of lactation improved feed intakes and milk yields. Adding high amounts of crude glycerol to a total mixed ration based on grass silage for mid-lactation dairy cows improved feed intakes with no negative effect on rumen pH, indicating its suitability as a component of a diet, at least when based on grass silage. In addition, replacing barley meal partially with unrefined glycerol increased milk protein content and improved curd firmness. Based on the experiments carried out it was concluded that, even at relatively high amounts, crude glycerol available from the biodiesel industry, is an appropriate feed supplement for dairy cows after calving, as well as in later lactation, under local feeding practices.
  • Pisipilt
    Kirje
    Effect of Milk Protein Composition and Genetic Polymorphism on Milk Rennet Coagulation Properties
    (Eesti Maaülikool, 2008) Jõudu, Ivi
    Piimal, millest valmistatakse juustu, peavad lisaks muudele kvaliteedinäitajatele olema head laapumisomadused (lühike laapumisaeg ja tugev kalgend), sest halvasti kalgenduvast piimast ei lähe osa kaseiini juustu koostisse, vaid jääb kaona vadakusse, põhjustades juustutööstustele suurt majanduslikku kahju, kuna juustu väljatulek väheneb ning kvaliteet halveneb. Paljudes arenenud veisekasvatusega riikides on leitud, et intensiivse aretustöö tulemusena on piimatoodang suurenenud, kuid piima laapumisomadused halvenenud. Samuti on suurenenud nende lehmade osakaal, kes võivad vähemalt korra laktatsiooni jooksul anda mittelaapuvat piima. Eestis läbiviidud varasemad (2000–2002) uuringud näitavad, et 8–9% piimaproovidest ei kalgendu üldse ning täiendavalt 17– 20% kalgenduvad halvasti. Mõnes karjas võib vähemalt kord laktatsioonil mittelaapunud piimaproovi andvate lehmade osakaal küündida meie andmetel kuni 39%ni. Antud uurimistöö moodustab ühe osa suuremast uurimusest, mille käigus selgitatakse näitajad, mille alusel on võimalik välja töötada võtted juustutootmiseks sobiliku piima saamiseks, ning suurendada selle abil piimatööstuse konkurentsivõimet. Töö käigus selgitati erinevate tegurite mõju piima laapumisnäitajatele (artiklid II, II, IV, V), leiti κ-kaseiini ja β-laktoglobuliini geneetiliste variantide esinemissagedus Eestis kasvatatavatel piimaveise tõugudel ning uuriti nende variantide mõju piima laapumisnäitajatele (II, II). Et nelja kaseiini geenid on aheldatud, siis uuriti eesti maatõu baasil piimavalkude geneetilist variatsiooni ja kaseiini agregaatgenotüüpide mõju piima laapumisnäitajatele (IV). Võrreldi eesti piimaveisetõugude piima valgulist koostist ning selgitati selle mõju piima laapumisnäitajatele (V). Seoses varem laialdaselt kasutatud piima laapumisnäitajaid mõõtnud seadme Formograaf väljavahetamisega Optigraafi vastu, leiti sobivaimad sisendid uuele seadmele ning lähendid, mis võimaldavad kasutada mõlema seadmega mõõdetud näitajaid üheaegselt andmeanalüüsis (I). Piima laapumisnäitajate võrdlusmõõtmisel 1. Optigraafi ja Formograafiga selgus, et mõlema seadmega mõõdetud laapumisajad korreleerusid tugevalt, kuid Optigraafiga mõõtes saadi oluliselt väiksemad väärtused. Pärast uute sisendite (R tõus = 1,784 ja R nihe = –2,303) rakendamist langesid mõlema seadmega mõõdetud piima laapumisajad kogu skaala ulatuses hästi kokku. NIR spektromeetrial baseeruva Optigraafiga leitud kalgendi tugevuse elektrilise näitaja konverteerimiseks varem kasutusel olnud pikkusühikuteks (Formograafil leiti kalgendi tugevus diagrammi harude vahelise kaugusena millimeetrites) saadi parim lähend, kui kasutati ruutfunktsiooni E30 = – 0,0357·A30 2 + 2,8795·A30 – 5,2991, kus E30 on kalgendi tugevus millimeetrites ja A30 on Optigraafil leitud kalgendi tugevus voltides. Leitud Optigraafi sisendid ja lähend kalgendi tugevuse ümberarvutamiseks võimaldavad võrrelda laapumisnäitajaid, mis on saadud erinevate mõõteriistadega, ja nende samaaegset kasutamist andmeanalüüsis (I). Nii piima laapumisomadused kui 2. ka koostiskomponentide sisaldused varieerusid suures ulatuses (I, II, IV, V). Mittelaapunud piimaproove oli 3–6% ja lõikamiseks ebapiisavalt tugeva kalgendiga proove 14– 16% (II, II, IV, V). Piima laapumisnäitajaid mõjutasid oluliselt laktatsioonijärk (II, IV), tõug (II), piima koostis (II, IV, V) ja piimavalkude genotüübid (II, II, IV). Laktatsiooni ja somaatiliste rakkude arvu mõju ei avaldunud nii selgelt (II, IV). 3. Piima laapumisomadused olid parimad laktatsiooni alguses ja halvimad laktatsiooni keskel. Laktatsiooni teisel poolel piima laapumisomadused paranesid (II, IV). 4. Piima laapumisnäitajad olid paremad κ-kaseiini BB-genotüübiga lehmadel. Halvemad piima laapumisomadused kaasnesid κ-kaseiini AA-, AE- ja EE-genotüüpidega. κ-kaseiini AB- ja BB-genotüüpidega lehmade piim oli kogu laktatsiooni jooksul keskmisest paremate laapumisnäitajatega. β-laktoglobuliini geneetilised variandid ei avaldanud olulist mõju piima laapumisnäitajatele (II, II). 5. Kõige sagedamini esines EHF ja RHF tõugu lehmadel κ-kaseiini AA- ning ER ja EN tõugu lehmadel AB-genotüüpi. Sagedasemad β-laktoglobuliini genotüübid olid AB ning BB. Eesti maatõugu ja eesti punast tõugu lehmadel esines κ-kaseiini B-alleeli sagedamini ning ka nende piima laapumisnäitajad olid paremad kui eesti holsteini tõugu lehmadel. Võrreldes varasemate (1972. a) Eestis läbiviidud uuringutega on piima paremate laapumisomadustega seostatava κ-kaseiini B-alleeli esinemissagedus eesti holsteini tõugu lehmadel märgatavalt vähenenud (II, II). Kuigi eesti maatõugu lehmadel oli piima laapumise seisukohalt soodsa κ-kaseiini B-alleeli esinemissagedus suhteliselt suur, esines see alleel enamjaolt heterosügootses kombinatsioonis A-alleeliga. Samas ei leitud eesti maatõugu lehmadel ebasoodsat E-alleeli, mida esines teistel Eestis kasvatatavatel piimaveise tõugudel (II, II, IV). Eesti maatõugu 6. lehmadel (n = 118) leiti 16 kaseiinide (αS1-, β-, κ-kaseiin) agregaatgenotüüpi, millest neli − BB A2A2 AA (21,2%), BB A1A2 AB (16,9%), BB A1A2 AA (14,4%) ja BB A2A2 AB (10,2%) – esines peaaegu kahel kolmandikul loomadel. Agregaatgenotüüp avaldas olulist mõju piima laapumisnäitajatele. Paremini laapus nende lehmade piim, kellel esines kaseiinide agregaatgenotüüp CC A2A2 AB või BC A1A2 BB. Võrreldes sagedamini esinevate agregaatgenotüüpidega lehmi, ilmnes, et piima paremad laapumisomadused kaasnesid BB A1A2 AB-genotüübiga. Piimavalgu juustuks konverteerimist soodustavaid κ-kaseiini BB- ja αS1-kaseiini BC- või CC-genotüüpe sisaldavaid agregaatgenotüüpe leiti eesti maatõugu lehmadel harva. Enamik mittelaapunud piimaproove saadi lehmadelt, kelle kaseiini agregaatgenotüüp sisaldas κ-kaseiini AA-genotüüpi (IV). 7. Piima peamiste valkude (αS1-, αS2-, β- ja κ-kaseiin, β-laktoglobuliin) sisaldust ja kaseiinide osatähtsust kogu kaseiinis mõjutasid oluliselt nii laktatsiooni- kui ka kalendrikuu. Võrreldes eesti holsteini tõugu lehmadega sisaldas eesti punast tõugu lehmade piim oluliselt rohkem valku, kaseiini, αS2-kaseiini ja κ-kaseiini ning β-laktoglobuliini, samuti oli αS1- ja κ-kaseiini osakaal kogu kaseiinis suurem. Piima laapumisaeg oli lühem ning moodustus tugevam kalgend, kui piim sisaldas rohkem valku, kaseiini, sh üksikuid peamisi piimavalkusid, ning kaseiini ja valgu suhe oli suurem. Tugevama kalgendi moodustamist soodustasid väiksem αS2- ja β-kaseiini või suurem κ-kaseiini osakaal kogu kaseiinis ning suurem κ-kaseiini suhe αS1- ja β-kaseiini (V). 8. Eesti punast ja maatõugu lehmade piima paremad laapumisomadused võrreldes holsteini tõugu lehmadega on osaliselt põhjendatavad paremate laapumisomadustega seostuva κ-kaseiini B-alleeli suurema esinemissagedusega (II, II, IV) ning eesti punasel tõul ka suurema piimavalkude sisaldusega (V). Selleks, et kasutada selle töö käigus saadud 9. geneetilist informatsiooni aretusprogrammides, tuleks määrata piimavalkude genotüübid nii aretuspullidel kui ka potentsiaalsetel pulliemadel. See on vajalik, et suurendada paremate piima laapumisomadustega seostunud alleelide esinemissagedust, samas vältides ebasoodsate alleelide esinemissageduse suurenemist (II, II, IV). Piima laapumisomadustega assotsieeruvate koostisnäitajate (nagu näiteks piima valgu- või kaseiinisisaldus) sobivus kasutamaks neid aretusprogrammides piima laapumisomaduste parandamiseks, vajab täiendavat uurimist. Sellealasteks uuringuteks annab hea eelduse OÜ Tervislike Piimatoodete Biotehnoloogiate Arenduskeskuse raames loodav andmebaas. Edasiste uuringutega tuleks välja selgitada ka piima mittelaapuvuse ja laktatsiooni keskel laapumisomaduste halvenemise põhjused.
  • Pisipilt
    Kirje
    Epidemiology of African swine fever in Estonia and characterization of one virus strain
    (Eesti Maaülikool, 2021) Nurmoja, Imbi; Viltrop, Arvo; Blome, Sandra; Depner, Klaus Robert; Dixon, Linda (opponent)
    African swine fever (ASF) is an OIE-listed, dangerous viral disease of pigs, which has a devastating impact on animal health and the pig industry in many countries worldwide. During the period 2014–2020, ASF has been the main animal health issue in Estonia. This dissertation consists of three independent studies, which have been conducted with the aim to analyse the epidemiology of ASF and the course of the epidemic in the Estonian wild boar population, as well as in domestic pigs. In Study I, wild boar surveillance data (n = 7,015) collected from two distinct study areas from September 2014 to September 2016 were analysed. A statistically significant difference between the two areas in the temporal course of ASF seroprevalence was found. These findings indicate that ASF might have been introduced to the north-east of Estonia earlier then to the south of the country. The probability of detecting an ASF-positive animal was higher in young animals (< 1 year). Within wild boar found dead, there was a higher probability of finding an ASF-positive result compared to hunted animals. In Study II, the biological characteristics of the ASF virus strain (Est 14/WB) circulating in the wild boar population of north-east Estonia in 2014 were evaluated. Oronasal inoculation of ten young wild boar led to an acute and severe course of the disease in all infected animals. Nine animals died and one animal recovered completely from the disease. In conclusion, the ASFV strain was still found to be highly virulent. In Study III, the epidemiology of ASF in all 26 domestic pig outbreak herds that occurred in Estonia during the period 2015–2017 was retrospectively analysed. On most of the farms, the first clinical signs were mild and not ASF-specific despite the high virulence of the circulating virus. The highest mortality (29.7%) was seen on backyard farms (1–9 pigs) and the lowest (0.7%) on large commercial farms (> 1000 pigs). The spread of the virus within farms was slow and the contagiousness of the virus was relatively low. Farms of all sizes and types have been at risk. The results suggest that the increase in ASF cases in local wild boar populations is the main risk factor leading to the infection of farms; 88% of domestic outbreaks occurred in areas where ASF virus was detected in wild boar prior to the outbreak, within a radius of 15 km from the outbreak farm.