No description available.

Please read the abstract in the section 00front of this document / Dissertation (MSc (Veterinary Science))--University of Pretoria, 2000. / Veterinary Tropical Diseases / unrestricted

Bovine fetal spleen cells synchronized with 2mM hydroxyurea were infected with bovine parvovirus and bovine enterovirus in order to study the events occurring when DNA and RNA viruses mixedly infect single cells. The objectives of this research were threefold. First, to determine the effects of single infection of synchronized bovine fetal spleen cells by bovine parvovirus and bovine enterovirus on cellular macromolecular syntheses. Second, to study the effect of simultaneous infection of synchronized cells by bovine parvovirus and bovine enterovirus. Third, to investigate the interactions which occur when synchronized cells are pre-infected with bovine parvovirus and superinfected with bovine enterovirus. Single infection of cells with bovine parvovirus upon release from hydroxyurea does not affect cellular macromolecular syntheses until 8 hr after infection; whereas, single infection with bovine enterovirus results in a rapid decrease in the rates of total DNA, RNA, and protein synthesis by 2 hr after infection. In simultaneously infected cells, the enterovirus replication is not inhibited while the level of parvovirus is severely reduced. However, in cells pre-infected with bovine parvovirus and super-infected with bovine enterovirus, the replication of both viruses is dramatically decreased. It can be seen from the results obtained in the study of two protocols of mixed infection, that many different virus-host interactions and virus-virus interactions can occur in a mixed infection. The time sequence of infection of the two viruses determines what interactions take place. / Master of Science

A dispersive liquid-liquid microextraction (DLLME) method has been developed, optimized and validated for the extraction of seven beta-agonists (Cimaterol, Cimbuterol, Clenproperol, Clenbuterol, Ractopamine, Isoxsuprine and Ritodrine) from bovine muscle. The homogenized tissue samples were hydrolyzed enzymaticaly by beta-glucuronidase and extracted with DLLME. The extraction parameters (pH, extraction solvent, extraction solvent volume, disperser solvent) were accurately optimized. Separation of the beta-agonists was by gradient elution on C18 LC column using acetonitrile and formic acid aqueous solutions as mobile phases, multiple reaction monitoring (MRM) scan mode was used. The seven beta-agonists were then simultaneous determined and identified in single analysis using 4000 Qtrap LC-MS/MS system. The DLLME method was validated using ISO 17025 and the EU criteria (Commission Decision 2002/657/EC) for validation of analytical method, good precision, repeatability and spiked recoveries were obtained. The limits of detection and quantification for the residues were between 0.0728 – 0.0922 μg/kg and 0.243 – 0.307 μg/kg respectively for beta-agonists. The overall recoveries were between 85% and 100% with the relative standard deviation of (RSDs) between 3.0% and 10%. The recoveries from the developed DLLME method were compared with those obtained from dSPE. DLLME proved to be comparable to SPE. The real samples test showed that the DLLME method developed is accurate and sensitive for the determination of beta-agonist residues in bovine muscle. / Chemistry / M. Sc. (Analytical Chemistry)

Focus of this study was on the development of one of the faster, simpler, cost effective and environmentally friendly sample pre-treatment techniques which employs a supported liquid membrane, in this case a Hollow-fiber supported liquid membrane (HF-SLM) for determination of seven (7) quinolone antibiotics (enrofloxacin, ciprofloxacin, danofloxacin, difloxacin, norfloxacin, nalidixic acid and sarafloxacin) in bovine kidney samples followed by LC-MS/MS analysis. The key parameters of the method were optimized and the method was validated following the 2002/657 EC guidelines. The optimum HF-SLM conditions were therefore; NaH2PO4 as a donor phase at pH 7, 0.1% formic acid at pH 3 as acceptor phase. Triethylamine was the optimized liquid membrane and the stirring time was optimized at 1 hour. Separation of the 7 quinolones including 3 internal standards (enrofloxacin-d5, norfloxacin-d5 and difloxacin-d3) was carried out on a Phenomenex Kinetex 2.6 μm XB-C18, 100 mm x 4.6 mm, 100Å column. Validation parameters such as Correlation coefficients (r2) ranging from 0.9714-0.9975 were obtained, while limit of detection (LOD) ranged between 3-39 ug kg-1 and limit of quantification (LOQ) ranged between 10-130 ug kg-1. The obtained limits at which it can be concluded with an error probability of α = 95% that a sample is non-compliant (CCα) ranged from 28 – 422 ug kg-1 while CCβ; the smallest content of the substance that may be detected, identified or quantified in a sample with an error probability of β = 95%, ranged from 29 – 454 ug kg-1. The method was found to be reproducible with CVs ≤ 23 %. The tested samples from Botswana local abattoirs showed no presence of quinolone antibiotics when the method was applied to real bovine kidney samples. Hollow-fiber supported liquid membrane can therefore be used for extraction of biological samples since it is a “greener technique” which uses less solvent which are less harmful to the environment when disposed as compared to dispersive Solid Phase Extraction (dSPE). / Chemistry / M. Sc. (Chemistry)

No description available.

The present investigation was made in the Laboratories of microbiology of the Ability of Cattle Sciences of the Polytechnic Superior School of Chimborazo, with samples obtained in the Municipal Camal Riobamba and the Community of Tunshi San Nicolás. The incidence of Brucellosis was analyzed in six more important cattle areas of the county using the antigens Brucella abortus and Rosa of Flare. The experimental units were obtained under a systematic sampling. The experiment had a duration of 4 months. The experimental results underwent the following analyses: variance, percentages, stockings, standard deviation, limit for the estimate error. According to carried out analysis of the obtained results, you determines that the analysis technique by means of antigen Brucella abortus, detected more cases of brucellosis (16.59% ± 4.61%) regarding the technique with Rosa of Flare (9.98% ± 3.59%). The biggest percentage of suspicious cases met with the technical Rosa of Flare (9.57% ± 3.35%) regarding the technique of antigen Brucella abortus (5% ±2.5%). According to the sex we have that in more quantity they presented the females with 9.16% in relation to the males with 7.1%, this with the antigen Brucella abortus. With Rosa of Flare we have for the females 5.42% and the males 4.42%. We carry out a study of 17 animals of the Community of Tunshi San Nicolás, we find completely free of this bacterial infection, with the two studied methods.

1. Gesundheits- und Hygienemanagement in ökologisch wirtschaftenden Betrieben mit Milchkühen 2. Untersuchung zur Optimierung von Kälberhaltungsverfahren – Haltung kleiner Kälbergruppen im Außenklima 3. Entwicklung und Erprobung eines Verfahrens zur Roséfleischerzeugung

A methodology for ageing foetal and neonatal cattle is developed, involving radiographic examination of infant mandibles for early developmental stages in molariform teeth; tooth-wear methodologies are imprecise at this stage before wear commences. Known-age modern bovine foetal and neonate material are collected as a control assemblage for method development (n=73); six Neolithic to Norse era assemblages from Orkney are examined using the modified technique together with standard tooth-wear analysis and other methodologies. Foetal and died-at-birth material is diagnosed at most sites using the new technique, together with a range of other peri-natal age-groups. Ageing at this early stage is highly relevant in the diagnosis of milking as a palaeoeconomy: the accepted view is that unwanted (male) calves were slaughtered to maximise milk for human consumption, hence a surfeit of neonate calf remains, as at the study sites. The diagnosis of foetal and died-at-birth material challenges this view, suggesting that attritional causes may have contributed to deaths at this stage. Although milking was probably carried out at most of the study sites, this may have been combined with slaughter of cattle for meat in a pragmatic exploitation strategy. Literary research shows possible attritional causes of abortion and early death in calves, in particular dietary insufficiency in pregnant cows, microbial infections, and also inadequate colostrum uptake. Additionally, research is used to consider the challenges to health that early milking might have posed, to the calf as mentioned, but also to the cow, where three main health issues are highlighted: infertility, mastitis and lameness.

No description available.