Thesis (Ph.D.)--Pacific Graduate School of Psychology, 1993. / Source: Dissertation Abstracts International, Volume: 54-12, Section: B, page: 6464.

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Raymond R. R. Rowland / Infectious cDNA clones of PRRSV make it possible to construct marker viruses for the study of virus replication and pathogenesis. The nonstructural protein 2 (nsp2) of porcine reproductive and respiratory syndrome virus (PRRSV) is the single largest protein produced during virus replication. The cDNA of the pCMV-129 infectious PRRSV clone was modified by creating unique Mlu I and SgrA I restrictions sites at nucleotide (nt) positions 3,219 and 3,614, respectively: both located within the C-terminal region of nsp2. cDNAs coding for oligo- and polypeptide tags, including FLAG, enhanced green fluorescent protein (EGFP) and firefly luciferase were inserted into the newly created restriction sites. The results showed that only the EGFP-containing genomes were properly expressed and produced virus. EGFP fluorescence, but not EGFP immunoreactivity, was lost during passage of recombinant EGFP viruses in culture. Sequencing of a fluorescence-negative EGFP virus showed that the EGFP remained intact, except for the appearance of mutations that may affect chromophore formation. The results show that nsp2 can be a site for the expression of foreign proteins. Removal of the region between Mlu I and SgrA I sites resulted in a virus that contained a 131 amino acid deletion. The deleted region was replaced with EGFP or an eight amino acid influenza hemagglutanin (HA) tag. Recombinant viruses were used to infect pigs. Gross and micro-histopathology showed reduced pathogenesis when compared to the parent wild-type virus. The 131 amino acid peptide, when expressed as a recombinant protein and coated onto enzyme linked immunosorbent assay (ELISA) plates, was recognized by sera from pigs infected with wild-type virus, but not the deletion mutants. The results from this study show that nsp2 is a potential target for the development of marker vaccines that can differentiate infected from vaccinated animals (DIVA) and for virus attenuation.

This study is a questionnaire-based, descriptive assessment of informal livestock slaughter practices by small scale farmers in Gauteng. This study aims to assess if the practice of informal slaughter poses a potential risk to public health specifically to brucellosis exposure, a disease of high seroprevalence in Gauteng and South Africa. Informal livestock slaughter from antemortem selection to carcass dressing, butchering and product preparation were descriptively assessed for potential disease exposure and resultant public health risk. This study assessed the frequency of brucellosis testing and the occurrence of livestock abortions as a possible disease indicator. Farmers were asked on the particulars of informal slaughter to ascertain if disease exposure could occur through this practice. The study made use of a questionnaire where 109 study participants were interviewed individually. Questionnaire results were compiled in Microsoft® Excel where data was analysed through descriptive statistics to identify trends and frequency data from the results. The study found that the majority of small-scale farmers participating in the study were older individuals, the majority of whom were not earning an income. It was found that study participants would slaughter livestock informally themselves or with a family member. This would occur only once or twice a year, usually for cultural or religious purposes or for a special occasion. Livestock most commonly owned and slaughtered by small-scale farmers were cattle, carriers of Brucella abortus. Participants rarely made use of adequate protective personal protective equipment (PPE) when slaughtering informally. The use of PPE and the adequacy thereof was however found to increase in frequency with participant age group. Older individuals, elders in their communities were often given the responsibility of livestock slaughter, thus providing some risk mitigation to disease exposure during the process. High risk structures such as lymph nodes and reproductive organs were handled during slaughter, the former frequently consumed with the tripe due to lack of recognition. While some organs previously found to harbour Brucella organisms were consumed raw or only exposed to short cooking times, the majority of slaughter products were exposed to prolonged cooking times, sufficient to reduce bacterial loads, reducing risk through consumption. While many participants recognised brucellosis as a zoonotic disease, the routes of transmission were poorly recognised. Exposure to Brucella spp. through informal slaughter is likely in the current environment of high brucellosis seroprevalence, poor disease control and the unreliable disease history of animals sourced for slaughter, posing a risk to public health. Should a brucella infected animal be slaughtered informally, exposure of those performing the slaughter, dressing the carcass and those involved in food preparation is likely and may lead to brucellosis. / Dissertation (MSc)--University of Pretoria, 2018. / Veterinary Tropical Diseases / MSc / Unrestricted

Rickettsia africae is a gram-negative bacterium which causes African tick bite fever (ATBF) in humans. ATBF is a febrile disease mainly affecting travellers to Southern Africa. This bacterium is known to be transmitted by Amblyomma hebraeum and Amblyomma variegatum ticks. In Southern Africa, the principal vector is A. hebraeum. This project was performed in a rural community in Mpumalanga province and aimed at addressing knowledge gaps of R. africae infection in A. hebraeum ticks. Infection rates in adult ticks and larvae as well as transovarial transmission efficiency of R. africae from the tick to its offspring were determined. To accomplish this, 106 adult A. hebraeum ticks were collected from cattle from Utah A and 106 from Welverdiend A. Larvae (n=1060) were collected by dragging at each of the two targeted dip tanks. Engorged female A. hebraeum ticks (n=53) were also collected from cattle from each of the two dip tanks and they were incubated in a humidity tank to oviposit and egg masses were collected from each tick. DNA was extracted from the engorged ticks and the egg masses as well as from the adult ticks and the larvae. After DNA quantification, a real-time quantitative PCR targeting Rickettsia gltA gene was performed to screen all samples for Rickettsia DNA. The gltA gene is common in all Rickettsia species. Samples positive for the gltA gene were subjected to conventional PCR targeting the ompA gene, which is specific for the Spotted Fever Group to which R. africae belongs. The samples positive for amplicons of ompA gene were sequenced and all the sequenced samples were found to be 99.98% identical to R. africae sequences from GenBank. From the sampled adult ticks, 13.43% tested positive for R. africae and 13.20% of the larvae also tested positive. The infection rate for larvae and adult ticks collected from Utah A was 15.09% and those from Welverdiend A was 11.79%. From these results, there were no notable differences in the infection rates of ticks at different stages of development. R. africae infection rates for the two study sites were found to be similar which can be an indication of even distribution of R. africae in this area. Transovarial transmission was found to be 100% in engorged female ticks collected from Utah and 71.43% in ticks from Welverdiend, which indicates a high transmission rate of the pathogen to the offspring of the vector. The presence of R. africae in A. hebraeum ticks from this area is a cause of concern since there are chances of people getting ATBF after bites by these ticks. / Dissertation (MSc)--University of Pretoria, 2019. / Veterinary Tropical Diseases / MSc / Unrestricted

In the Bushbuckridge Local Municipality (BLM), Mpumalanga, the size and economic importance of the local, mostly informal, cattle trade has been considered negligible to date by local policy makers. Opportunities for the local cattle farmers to access formal live or product markets remain severely limited, mainly as a result of movement restrictions associated with foot-and-mouth disease (FMD) control. Data, in the form of movement permits and monthly cattle registers were used to analyse movement and trade activity in the area over a four-year period (May 2015 - April 2019). The population fluctuated around 77 166 head of cattle, distributed between 9739 emerging rural livestock farmers. The proportion of animals/products moved ranged between 3.1 and 7.2 percent (0.04 ± 0.02). Movements were found to be highly seasonal (p < 0.001) with the ‘cool dry’ season (April-July) being the most active. Most movements consisted of live cattle which were herded to their destinations. The vast majority of trade did not leave Bushbuckridge and was informal in nature. Farmers moved animals and products much further to access formal markets (p < 0.001) than informal markets, and generally required use of motorised transport to do so. The FMD outbreak of 2017 did not prove detrimental to the local cattle industry in the medium term. However, distinct changes to the overall Bushbuckridge herd dynamics were noted, with small scale farmers most severely affected. As a direct result of the heightened movement restrictions in this period, an estimated 96% of formal trade; 85% of informal trade, and 54% of local trade were lost. In 2018, an improvement in cattle prices stimulated farmers to access the formal marketplace, and an increase in the proportion of the cattle population moved was observed. It was concluded that farmers pursue formal marketing options only when financially incentivised or pressurised by adverse conditions such as environmental factors or disease outbreaks. Growing established local markets is likely the best way to assist the local population with market access, development and poverty reduction. The key constraints to marketability of animals/products originating in the BLM were identified as the absence of a competitive market system and associated infrastructure such as FMD designated abattoirs, disease control regulations, poor carcass quality, and seasonality of offtakes. These limitations will need to be considered when policy decisions are made. Context-specific solutions should be generated to address local needs and effectively support development of a sustainable cattle trade going forward. / Mini Dissertation (MSc (Tropical Animal Health))--University of Pretoria, 2019. / Veterinary Tropical Diseases / MSc (Tropical Animal Health) / Unrestricted

In rural areas of developing countries like South Africa, people typically depend on goat farming for both meat and milk production due to the shortage of grazing and the higher maintenance cost of cattle. An understanding of the functionality of the mammary gland and subsequent drug transport into milk are important factors in determining milk withdrawal periods and drug residues in milk intended for human consumption. Tight cellular monolayers, cultured to resemble the in vivo blood-milk-barrier, are used to evaluate the transepithelial transport of drugs into milk in vitro. The aim of this study was to culture and maintain tight monolayers of primary Boer goat mammary epithelial cells that would be a barrier to paracellular drug movement. Cells were cultured and maintained similarly to the method described by Pantschenko and colleagues (2000), with some adaptations and with MCF10a as growth medium. The formation of tight barriers was evaluated by measuring transepithelial electrical resistance (TEER) and the paracellular movement of dextran-FITC. An aggregated monolayer was established which had the characteristic cobblestone appearance, typical of epithelial cells, with no fibroblasts seen microscopically. On day 11 the monolayers appeared to be confluent under microscopic examination, they presented a significant barrier to the movement of FD70 dextran (Papp = 0.001), and the transepithelial electrical resistance (TEER) was greater than 200 ?.cm2. At day 18 of culture, macroscopically the cells started to stack and cell debris formed, presumably due to overgrowing and cell differentiation, and the monolayers were no longer appropriate for use. Furthermore, cryopreservation techniques were performed on the cells and these cells were frozen, stored, and regrown as viable epithelial cells. Primary Boer goat mammary epithelial cells, cultured and maintained using the methods described in this dissertation, form tight monolayers that are a significant barrier to the paracellular movement of relatively large molecules like dextran70, with TEER values appropriate for xenobiotic transcellular flux studies between day 11 and 18 of culture. This timeframe corresponds with the time in which drug transfer studies are typically done in cell cultures from other species. Viable cryopreservation of Boer goat mammary epithelial cells is a useful tool that can be used to enhance these studies. / Dissertation (MSc)--University of Pretoria, 2015. / tm2016 / Paraclinical Sciences / MSc

Master of Science / Department of Diagnostic Medicine/Pathobiology / Gary A. Anderson / Foot-and-mouth disease (FMD) is a highly infectious viral disease of cattle, pigs, sheep, goats, buffalo, and artiodactyl wildlife species. Foot-and-mouth disease virus is endemic and periodic devastating epidemics have occurred and caused heavy economic losses in Iraq for a long time. The first official cases of FMD were recorded in 1937, while the first record of a specific FMD serotype in Iraq was serotype A in 1952. Other serotypes have been reported since then; serotypes O, SAT-1 and Asia1 were recorded in 1957, 1962, and 1975, respectively. Veterinary Services in Iraq has been severely weakened over the past two decades, and its infrastructure has been devastated as a consequence of previous political conflicts, wars and international sanctions. The breakdown of Veterinary Services led to the disruption of disease control strategies, collapse of disease surveillance and monitoring, and weakening of response systems. The destruction of the Al-Dora FMD laboratories for diagnosis and vaccine production by the United Nation in 1996, and the restrictions placed on the importation of vaccines have strongly affected the FMD control program. A severe epidemic of FMD occurred in Iraq in 1998, affecting 2.5 million ruminants and causing heavy losses in newly born animals. It is estimated to have killed about 550,000 animals. The outbreak was due to the serotype O1 Middle East strain which has affected large and small ruminants. In 2009, Iraq was severely affected by new serotype A (subtype A Iran 05). The major efforts of Veterinary Services in Iraq have been directed towards control of FMD by vaccination strategies. Two types of vaccine have been used, trivalent vaccine (O, A 22, and Asia 1) for cattle and buffalo and monovalent vaccine (O Manisa) for sheep and goats. Vaccination has been implemented once yearly on a voluntary basis. Sometimes other limited control measures have accompanied vaccination, which include quarantine, movement control, focused vaccination, disinfection, and public awareness programs. The FMD control program in Iraq has been confronted by many challenges: deficits in FMD surveillance and emergency preparedness, limited diagnostic capabilities, difficulties in restricting animal movement, and lack and irregular supply of appropriate vaccines.

Master of Science / Department of Clinical Sciences / David E. Anderson / Lameness in cattle is a common cause of pain however there are no approved cattle analgesic drugs. Flunixin meglumine, the only non-steroidal anti-inflammatory drug approved for use in adult dairy cattle, is labeled for pyrexia associated with bovine respiratory disease, endotoxemia, acute mastitis and associated inflammation. There is currently a lack of objective data regarding the analgesic efficacy of flunixin meglumine in cattle. The objectives of this study were to characterize an amphotericin B-induced lameness model and to ascertain the analgesic effects of flunixin meglumine using multimodal assessment. We hypothesized that flunixin meglumine would provide analgesia as evidenced by increased activity levels as well as increased exerted force and contact area on the affected limb in flunixin treated steers. Amphotericin B-induced synovitis arthritis was induced in the distal interphalangeal joint of 10 dairy steers. The cattle were randomly allocated between a treatment and a control group. The treatment steers received flunixin meglumine at the time of arthritis induction and at 12 hours post-induction. Accelerometric, gait, pressure mat, vital parameter and plasma cortisol data were gathered in the pre and post-induction phases. The data were analyzed using linear mixed models with treatment and time designated as fixed effects. Induction of amphotericin B arthritis produced a moderate, transient lameness. Control steers were more than twice as likely to be lame as flunixin meglumine treated steers using visual lameness assessment (92.2% ± 8.1 versus 40.7% ± 2.5) (P<0.03). Flunixin meglumine treated steers placed significantly greater force and contact area on the affected foot. Control steers also placed significantly greater force, impulse and contact area on the paired claw as compared to control steers. Flunixin treated steers spent considerably less time in recumbency than their control counterparts, particularly in the immediate post-induction time period. This is one of the first studies to document the character of an amphotericin B-induced synovitis arthritis model in cattle as well as to document analgesic efficacy of a nonsteroidal anti-inflammatory drug in an induced lameness model. Flunixin meglumine was efficacious in providing analgesia in an amphotericin B-induced lameness model in dairy steers.

Endocrine regulation of expression of GnRH receptors is an important step in the control of reproduction. During the early follicular phase of the estrous cycle in the ewe, GnRH receptor expression increases in preparation for the preovulatory surge of LH. The studies described herein were designed to further elucidate the hormonal interactions controlling GnRH receptor expression. In long-term ovariectomized ewes, neither removal of progesterone, nor the presence of estradiol affected the expression of GnRH receptors. However, in ewes ovariectomized during the luteal phase of the estrous cycle and immediately implanted with progesterone and estradiol for 48 hours, low levels of estradiol for 24 hours were required to increase GnRH receptor mRNA following the removal of progesterone. In ovariectomized ewes following hypothalamic-pituitary disconnection, low levels of estradiol and pulsatile GnRH were required to increase GnRH receptor expression within 24 hours of treatment initiation. These results suggest an interaction between estradiol and GnRH is involved in increasing GnRH receptor expression during the periovulatory period. How progesterone, estradiol and, GnRH interact to increase GnRH receptors is unknown, but a possible candidate involved in mediating these interactions may be the cell specific transcription factor, steroidogenic factor-1 (SF-1). SF-1 mRNA increased within 24 hours of treatment of ewes with prostaglandin F₂(α) compared to ewes in the luteal phase of the estrous cycle. This suggests that progesterone may have an inhibitory effect on SF-1 mRNA. SF-1 mRNA was similar between ovariectomized ewes and ovariectomized ewes following hypothalamic-pituitary disconnection treated with estradiol and GnRH. Treatment with estradiol or GnRH alone did not increase SF-1 mRNA. The results of these experiments suggest that progesterone removal as well as the presence of estradiol and GnRH are required to increase GnRH receptor expression during the early follicular phase in the ewe. Further, the transcription factor, SF-1 may be involved in mediating the effects of these hormones on GnRH receptor expression.

<p> Research has shown that direct-fed microbials (DFM) and enzyme supplementation can impact the dry matter intake (DMI), milk production, and milk composition. However, limited research has evaluated the impact of DFM and enzyme supplementation on colostrum quality and the uptake of the Immunoglobulins A and G (IgA and IgG) by calves. In this study, 36 multiparous Holstein cows were blocked by expected calving date and randomly assigned to 1 of 3 treatments 3 weeks prior to calving and remained on these treatments until week 8 postpartum. These treatments were: 1) 0 g of DFM and enzyme (control), 2) 45.40 g/d of Tri-Lution&reg; (Tri), or 3) 45.40 g/d of Tri-Lution&reg; and 18.16 g/d of Zy-mend&reg; (Tri + Zy). The amount of total mixed ration (TMR) fed and orts refused were measured each day to determine DMI. Blood samples were taken on the cows every Monday, Wednesday, and Friday at 1100 h from the coccygeal veins and arteries to be analyzed for &beta;-hydroxybutyrate (BHBA), glucose, and nonesterified fatty acids (NEFA). Cows were also weighed once a week throughout the course of the study. Colostrum was harvested and weighed at parturition and later analyzed for IgA and IgG concentration via radial immunoassay. Calves were fed 4 L of maternal colostrum within 2 h after calving. Blood samples were also taken from the calves at 0 and 24 h in order to be analyzed for IgA and IgGconcentrations and to determine apparent efficiency of absorption of IgA and IgG. Finally, milk yields were taken daily for 8 wk postpartum and samples were taken once a week and sent to DairyOne (Ithaca, NY) to be analyzed for quality. Prepartum body weight (BW), BW, efficiency of gain, DMI, BHBA, NEFA, and glucose concentrations were not impacted by treatment. There was also no impact of treatment on colostrum yield, IgA and IgG content, and composition with the exception of IgA yield and ash percentage. The ash percentage of colostrum tended (<i>P</i> = 0.07) to increase with the Tri and Tri + Zy treatments while the IgA yield (<i>P</i> = 0.05) decreased with the Tri treatment. Treatments did not impact BW, serum IgA and IgG concentrations or apparent efficiency of absorption of IgA and IgG of the calves. Postpartum BW, DMI, blood metabolites, milk production and composition, with the exception of BW gain and somatic cell score (SCS), of the cows were not impacted by treatment. Cows on the Tri treatment gained more BW (<i>P</i> =0.03) and tended to have a greater efficiency of gain (<i>P</i> = 0.09) in comparison to those on the Tri + Zy treatment, but both treatments did not differ from the control. This suggests that there is a negative effect of applying the Tri-Lution&reg; and Zy-mend&reg; together which might be due to negative interactions among ingredients and microorganisms. An increase in SCS (<i>P</i> = 0.04) was also observed with the Tri treatment. All these results indicate that the supplementation of DFM and enzymes is not beneficial in improving the health and performance of dairy cattle during the transition period and early lactation.</p>