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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Evaluation of microsatellite markers for parentage verification in South Africa Angora goats

Friedrich, Henriëtte 01 September 2010 (has links)
South Africa is currently the world leader in mohair production and emphasis is placed on mohair traits to ensure the production of a high quality clip. Accurate and complete pedigree information is a prerequisite for accurate selection and estimation of breeding values that in turn can improve the traits associated with fleece quality and yield. South African Angora goats are farmed under extensive breeding conditions in relatively large herds. As a result breeders make use of mating systems that tend to limit accurate parentage recording. Incorporation of genetic parentage testing into the breeding plan can improve the accuracy of pedigree records and lead to increased selection accuracy. Microsatellite markers were evaluated for inclusion into a parentage verification panel, to be applied in the South African Angora goat population. The panel of 18 microsatellite markers was constructed, optimized and tested in 200 South African Angora goats. These goats represented different family structures, including candidate parents alone as well as known and candidate parents. The microsatellite markers were evaluated based on the number of alleles, allele frequency, PIC, HE, HO and CPE of each individual marker and as a panel. Four microsatellite markers were excluded from the panel based on their poor performance for the above mentioned parameters. The panel of 14 markers allowed a cost effective panel with the highest exclusion power. The CPE1 of the 14 microsatellite marker panel was 99.73%. The use of molecular parentage verification may aid Angora goat breeders in improving the accuracy of the parentage records of their animals. Copyright / Dissertation (MSc (Agric))--University of Pretoria, 2010. / Animal and Wildlife Sciences / MSc(Agric) / Unrestricted
2

The influence of dual CYP17 expression on adrenal steroidogenesis in the South African Angora Goat

Storbeck, Karl-Heinz 12 1900 (has links)
Thesis (PhD (Biochemistry))--Stellenbosch University, 2008. / This study describes: • the cloning and sequencing of cytochrome P450 17 -hydroxylase/17,20 lyase (CYP17), 3 -hydroxysteroid dehydrogenase (3 HSD) and cytochrome b5 from the South African Angora goat; • the identification of two CYP17 genes encoding two unique CYP17 isoforms in the Angora goat; • the development of a UPLC-APCI-LC method for the separation and quantification of seven adrenal steroids; • the characterisation of the enzymatic activity of the two Angora CYP17 isoforms expressed in non-steroidogenic COS-1 cells. The Km and Vvalues for the metabolism of pregnenolone and progesterone were determined; • the development of a rapid and accurate real-time PCR genotyping test for CYP17 in Angora goats. Three unique genotypes were identified; • the determination of blood cortisol levels upon the stimulation of the HPAaxis by intravenous insulin injection in the three Angora goat genotypes.
3

Attenuated heartwater vaccine (Ehrlichia ruminantium Welgevonden) : immunization of Angora goats using the intra-muscular route of administration

Haw, Anna January 2013 (has links)
Ehrlichia ruminantium, the causative organism of heartwater infections, places severe economic constraint on the livestock industry wherever Amblyomma tick vectors are present. Angora goats are particularly susceptible to this disease and the current live blood vaccine cannot safely be used to protect these animals. An attenuated E. ruminantium (Welgevonden) experimental vaccine has previously shown promising results in Merino sheep and Boer goats. The vaccine was administered by intravenous route (i/v). The general objective of this study was to test the efficacy and safety of the attenuated heartwater vaccine E. ruminantium (Welgevonden) in Angora goats. The specific objectives were, firstly to assess the intra-muscular route of administration of the attenuated vaccine as compared to the standard i/v route and, secondly, to study the haematological changes in Angora goats before, during and after vaccination under controlled conditions at the Onderstepoort Veterinary Institute tick-free stables. A total of 55 Angora goats were used in this trial. They were purchased from an area in South Africa which is known to be Amblyomma-free and heartwater-free. Furthermore, on arrival, the goats were screened for E. ruminantium infection by the immunofluorescent antibody (IFA) test to confirm their disease-free status. The Angora goats were divided into 3 groups: In Group 1, ten were vaccinated by the standard i/v route, in Group 2, 31 received the vaccine by i/m route and 10 served as untreated controls for Group 3. Five of the 10 i/v vaccinated group, 20/31 of the i/m vaccinated and 5 controls were challenged by feeding of known infected adult A hebreaum. The other remaining animals within the three groups were challenged using a known infected blood stabilate administered by the standard i/v route (dose 5xLD50). All animals were challenged 42 days after vaccination. The vaccine did not produce any inflammatory reactions at the site of injection. However, 3/31 (9.7%) of i/m and 7/10 (70%) of i/v vaccinated goats developed febrile reactions starting on Day 11 post-immunisation and were treated. All vaccinated goats were fully protected against either needle i/v or tick challenge, while the control non-vaccinated goats reacted severely to the challenge materials and required oxytetracycline treatment. Despite treatment, two of the unvaccinated goats died from the challenge material. 9 Haematological values (packed cell volume, differential blood cells count) were obtained on blood samples taken from the treatment and control groups at different times during the course of the trial. Wide within group variations as shown by the high standard deviation values were found. As no significant changes were found between vaccinated and control animals, it is likely that the attenuated vaccine does not cause significant clinical haematological changes. This study has demonstrated that the attenuated E. ruminantium (Welgevonden) vaccine is safe in 90.3% and efficacious (100% efficacy) for intramuscular administration in Angora goats. However, further laboratory and on-farms studies are needed in order to establish the lowest effective and safety dose, duration of immunity, and the vaccine’s safety in young and pregnant animals. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Veterinary Tropical Diseases / unrestricted
4

A molecular approach to genetic improvement of South African Angora goats

Visser, Carina 19 October 2011 (has links)
South Africa is considered the primary producer and most reliable source of high quality clip mohair in the world. The application of molecular technologies to improve mohair quality is relatively new to this industry. The aim of the study was to use a molecular approach to genetically improve South African Angora goats, with emphasis on mohair production. A reference population of Angora goats was firstly established consisting of twelve sire families with half-sib offspring (1067 individuals in total). The genetic variation of this population was evaluated using microsatellite markers and the average gene diversity was found to be above 60%. Ninety four microsatellite markers were then genotyped on the reference population, spanning 23 chromosomes (total length 1352cM) with an average marker interval of 23.0cM. This information was used to improve previously published goat linkage maps. Unmapped microsatellite markers were incorporated and previously published inter-chromosomal rearrangements between the goat and sheep genetic maps were confirmed or rejected. Nine new markers were mapped to the goat genome, and six chromosomes showed rearrangement when compared to the previous goat map. Four previously reported intra-chromosomal rearrangements were shown to be either population specific or mapping errors. Variance components and genetic parameters of mohair traits (FW, FD, CVFD, SDFD, CF, SF and SDA) were estimated; including the fibre diameter profile measured using OFDA technology that has not yet been included in genetic evaluations. Heritability estimates ranged between 0.14 (SDA) and 0.63 (CF). OFDA-measured traits should be considered for inclusion into the national breeding strategy. The reference population was lastly analysed to identify QTL associated with fleece traits. Eighteen putative QTL were identified for seven mohair traits on 13 chromosomes. Three putative QTL were detected for FW on CHI 2, 5 and 24 corresponding with KRT and KAP gene locations. Two QTL associated with mohair FD (on CHI 4 and 24) were detected. QTL contributions to variance ranged between 7.44% (CF) and 19.69% (SDA). The results of this study should form part of an integrated approach where both quantitative and molecular tools are applied for genetic improvement of South African Angora goats. / Thesis (PhD)--University of Pretoria, 2011. / Animal and Wildlife Sciences / PhD / Unrestricted
5

Determining thermal stress during the transport of mammals

Wimberger, Kirsten 01 November 2006 (has links)
Student Number: 0218322F Master of Science School of Physiology / The high morbidity and mortality of wild mammals and livestock during capture and transport is generally ascribed to thermal stress. Consequently, capture operators can benefit from improved methods that may reduce thermal stress. The aim of my study was to develop a practical method of measuring the body temperature of mammals during capture and transport operations. Firstly, I determined whether intermittent temperature recordings, which allow for minuteby- minute monitoring of an animal’s temperature, could accurately reflect continuous measures of an animal’s rectal temperature. Intermittent temperatures were measured via telemetry while continuous and off-line recordings were measured with data loggers. Secondly, I compared rectal and abdominal temperatures to determine if rectal temperature can provide a practical, noninvasive method of estimating core body temperature. Additionally, I measured body temperature and environmental conditions throughout transportation and compared pre- and post-transport levels of faecal cortisol, and blood cortisol, haematocrit and catecholamines. Measuring rectal temperatures seems to be the only feasible, non-invasive technique to obtain temperature during transport operations. However, rectal temperature records required about 30 minutes to stabilise after inserting a thermometric device. After rectal temperature stabilised, generally the difference between abdominal and rectal temperatures varied greatly for individual animals, while the average differences in temperatures between the body sites were not significant for all, except one, species. I have also shown that telemeters and data loggers can be used interchangeably to measure the body temperature of animals. The differences between temperatures measured by the devices were not significant, except for substantial differences shown in two animals. The addition of earphones and a large aerial inside the vehicle improved the telemetry results, by limiting the extraneous noise of the capture and transport environment. These conditions probably caused the anomalous readings in the two animals. General thermal responses to stress are that animals showed a peak in temperature due to capture and a decrease in temperature during transport. Therefore, capture-related stress and the likelihood of animals dying during capture could be minimised by ensuring that the animals are not chased longer than a set cut-off time. Further, globe temperature should be monitored to ensure that animals are not captured in high thermal conditions. In contradiction with the current guidelines regarding the appropriate time of day for capture, I recommend that animals should not be caught at the end of the day, as my results show that this is when their body temperatures are the highest. Body temperatures during transport and differences in faeces cortisol before and after transport seem to indicate that animals adapt to repeated stress events.

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