Doctor of Philosophy / Department of Biological & Agricultural Engineering / Ronaldo G. Maghirang / This research was conducted to investigate the potential of charged-water spray in controlling dust in livestock buildings. Specific objectives were to: (1) develop a method to measure the electrostatic charge of airborne particles; (2) characterize the size distribution and charge of airborne particles in a livestock building; (3) evaluate the effectiveness of charged-water spray in controlling dust concentration in enclosed spaces under laboratory conditions; (4) model the effectiveness of charged-water spray in controlling dust in an enclosed building; and (5) develop and evaluate an electrostatically-assisted particulate wet scrubber (EAPWS). A dynamic Faraday-cage sampler was developed for measuring the net charge-to-mass ratio of particles. The device involves collecting particles on a filter and measuring the charge induced. The sampler was calibrated and then used to measure the charge of dispersed particles (i.e., corn starch, NaHCO3, positively charged water spray, negatively charged water spray, and uncharged water spray). The corresponding net charge-to-mass ratios were -0.11 (SD=0.07), +0.20 (0.001), +7.24 (1.6), -6.47 (0.9), and -0.30 (0.12) mC/kg. Characterization of dust in a swine building showed mean dust concentration of 0.89 (SD=0.45) mg/m3, geometric mean diameter of particles of 9.34 μm, and geometric standard deviation of 2.11. The Faraday-cage sampler was also used in the swine building; the net charge-to-mass ratio of particles was +0.68 mC/kg (SD=0.31 mC/kg). The effectiveness of charged-water spray in reducing dust concentration was investigated in an experimental chamber. Test particles (i.e., corn starch, NaHCO3) were dispersed into the chamber and then charged water was sprayed into the chamber. The charged-water spray was significantly more effective than either the uncharged-water spray or no water spray. The removal efficiency of the charged water spray (4 min spray duration, 120 mL/min), based on mass, ranged from 88% to 92% for particles ≤ 10 µm equivalent aerodynamic diameter (EAD) and from 34% to 70% for particles ≤ 2.5 µm EAD. A model based on coagulation was used to predict the particle concentration after spraying of charged water. Predicted values of concentration and removal efficiency agreed well with measured values. A prototype EAPWS was also developed. Laboratory and field evaluations of the EAPWS indicated that it had significantly higher particle removal efficiency than either the control (i.e., no water spray) or the uncharged wet scrubber.

Doctor of Philosophy / Department of Agricultural Economics / Terry Kastens / The production of corn-based ethanol in the U.S. has increased from 1,630 million gallons in 2000 to 4,855 million gallons in 2006, representing a 198% growth over the period considered. This growth is favored by the availability of more efficient technologies in the production process of ethanol and is sustained by the high prices of ethanol in the market. The industry is also supported by a favorable public policy, expressed in the form of laws, mandating an increase in the use of ethanol, and also in the form of tax incentives. The tremendous increase in the use of corn for the ethanol industry is made at the expense of the livestock industry that was the traditional destination for much of the U.S. corn grain. As the ethanol industry continues to expand, concerns are raised in regard to its impact as more and more corn is diverted from the livestock sector. This study investigates the economic impact of the ethanol industry on the U.S. livestock sector. Specifically, a shipping cost model is developed to simulate the impact of the ethanol industry on the shipping cost of corn at the national and individual state levels. The dynamics for major livestock producing states are also analyzed at the crop reporting district level. Different scenarios based on assumptions on the availability of corn and the production capacities of the ethanol industry are displayed. Results from the model indicate that nationwide there is a 5 to 22% increase in the shipping cost of corn for the livestock industry due to the ethanol industry, depending on the scenario involved. At the state level, there is an increase in the transportation cost for most of the states, with shipping cost doubling in some cases. Nevertheless, some states benefit from the dynamics created by the development of ethanol plants and are experiencing a reduction in their livestock industry corn transportation cost.

Please read the abstract in the section 00front of this document / Dissertation (MSc Agric)--University of Pretoria, 2007. / Agricultural Economics, Extension and Rural Development / unrestricted

Livestock farmers on communal land rely heavily on state veterinary services (SVS) for animal health care. State provided primary health care services are however, not readily accessible to many such communities. The study was conducted to investigate the primary animal health care (PAHC) delivery methods that are preferred by communal land-based livestock farmers, with special focus on the possibility of using community-based animal health workers (CAHW). The study was conducted in Mnisi community in Bushbuckridge local municipality of Mpumalanga Province. Questionnaire-based interviews were conducted with 133 cattle farmers from 10 of the 15 inspection points in Mnisi community. After analysis of the data from the questionnaire surveys, group discussions were held at five inspection points to obtain clarity on the community’s needs and expectations for the delivery of PAHC services. Data was captured and analysed in Microsoft Excel using descriptive statistics. Responses from the group discussions and other interviews were captured and reported on. The respondents were predominately male (72 % of all respondents), owners of the livestock (80%) and had an average of 13 cattle each. The major reasons given for the exit of cattle from the herds were sales (38% of exits), drought (18.2%), stock theft (15.6%) and diseases (14.8%). Overall 55.1% of exits were losses while 43.7% were for beneficial purposes (1.2% of the exits from the cattle herds were not explained). The farmers perceived nutritional problems, animal diseases, access to water, stock theft, drought and ticks/dipping the six important constraints to livestock production. Amongst diseases and disease conditions, tick burdens, lumpy skin disease and internal parasites were considered the major challenges. Most farmers (77%) did not vaccinate their cattle. The main reason that was given for not vaccinating cattle was that vaccines were provided free by the SVS. None of the farmers felt that the vaccines were not available, not effective or too cumbersome to apply. Despite the free vaccines, 67% did not know if their cattle were ever vaccinated and or what diseases the administered vaccines prevented. All farmers controlled ectoparasite infestation either by plunge dipping (90.2%) or use of pour-on acaricides (9.8%). Furthermore, 78% of those who dipped their cattle also used other methods to control ectoparasites, popularly, whole body and/or spot spraying as and when it was necessary. Endoparasites were controlled by 59.4% of the respondents, predominately by drenching as and when it was necessary. The alternative products for ectoparasites and endoparasites were obtained mainly from the farmers’ cooperative in Hoedspruit. For 99% of the respondents the primary providers for animal health care in Mnisi were SVS professionals (predominately Animal Health Technicians, AHTs). Other community members were consulted by 30% of the respondents. The common routes of contact were visiting the SVS offices, contact at the inspection points and calling the officials with a cell phone. Two-thirds of the farmers reported diseases to SVS and most of them (94%) were happy with the response to the reports. In general the farmers were satisfied with the accessibility of the AHTs (72%), state veterinarians (95%) and the animal clinic staff (77%). They were also satisfied with the information that they received from SVS. The most preferred providers of animal health care were the AHTs (77%). When prompted, 92% of the respondents said they would use the services of a community-based person trained to handle animal health problems, mainly for advice on disease management, drug administration, disease surveillance, diagnosis and castration. During the group discussions, facilitating access to fodder and water were included in the tasks for the community-based persons. Forty-two percent of the respondents said that they would use such a person frequently and 83% were willing to pay for the services in cash and/or kind. The general impression was that young people should be trained to carry out these tasks. Farmers preferred that the community-based person should work closely with the AHTs and be in contact with the farmers as frequently as 2–3 times a week to monthly. It is concluded that farmers of Mnisi community were satisfied with the availability and accessibility of the PAHC services provided by the SVS, and in fact preferred the SVS for this service. The farmers however lacked the knowledge and ability to adequately handle the production, animal health and livestock security problems with which they were confronted. A community-based service would therefore be beneficial if it holistically addressed the critical challenges of access to fodder and water, control of diseases and ticks, ensured livestock security, and also equipped farmers to manage these challenges. It is therefore recommended that Community-based Livestock Workers could be engaged if they are adequately qualified to fulfil this role. The use of Farmer Field Schools facilitated either by AHTs or CLWs for capacitation of the farmers should be investigated. The cost implications, potential benefits and effectiveness of selected options should be explored further before conclusive decisions are taken. It is further recommended that some effort should be invested in stimulating community cohesion amongst farmers to enable them to collectively address challenges that are common to them. The needs for the delivery of PAHC services in Mnisi community illustrate that such services should be tailor-made for the intended beneficiary communities, taking into consideration the existing support structures, the communities’ socio-cultural issues, cost effectiveness and the possible impact of the services. Copyright / Dissertation (MSc)--University of Pretoria, 2012. / Veterinary Tropical Diseases / unrestricted

The neuroparalytic syndrome called botulism is caused by the neurotoxins produced by bacteria in the genus Clostridium. There are seven toxigenic types of C. botulinum (A to G) based on antigenically distinct toxins produced by different strains of the organism. Animal botulism is caused by C. botulinum type C and D neurotoxins and has a severe economic impact on cattle farming in South Africa and neighbouring countries. Current treatment regimes include the use of acetylcholine for symptomatic treatment, but this is unfortunately very seldom successful. All indications are that there is no cure for this disease and that effective control can only be achieved through development of efficacious vaccines. The botulinum vaccine currently in use in South Africa contains an adjuvanted toxoid form of the type C and o neurotoxins. However, this bivalent vaccine relies on problematic anaerobic cultivation of the Clostridium bacterium followed by isolation, purification and inactivation of the toxin by treatment with formalin. Apart from the fastidious growth requirements of this organism, it has been reported that the production of toxin by these cells declines rapidly and eventually ceases, following laboratory passaging of the bacterial cultures. In addition, improper inactivation of the toxins may also lead to the demise of animals following vaccination. Thus, there exists a great need for a safe, effective and inexpensive vaccine against botulism. To investigate the potential of types C and D botulinum neurotoxins as efficacious recombinant vaccine candidates against botulism, full-length copies of the genes were obtained by polymerase chain reaction (PCR) amplification from bacteriophage DNA isolated from Clostridium botulinum type C (Stockholm) and D (South Africa) cultures. The full-length genes were cloned and subsequently sequenced to verify their integrity. By making use of PCR-based site-directed mutagenesis procedures, three amino acid mutations were introduced in the zinc-binding motif of the respective neurotoxins. Mutation of this domain has previously been reported to successfully detoxify type C neurotoxin. The wild-type and mutant genes were subsequently expressed in insect cells using the BAC-to-BAC™ baculovirus system. Although, unique protein bands corresponding to the size of the neurotoxins could not be seen in Coomassie brilliant blue-stained gels, Western blot analysis indicated immunoreactive material for wild-type and mutant type C corresponding to the size of the type C toxin light chain. However, there was no conclusive evidence to support the successful expression of the full-length wild-type and mutant type D genes. / Dissertation (MSc (Microbiology))--University of Pretoria, 2006. / Microbiology and Plant Pathology / unrestricted

Agriculture is one of the most hazardous industries in the United States, with a fatality rate that consistently surpasses other industries. Livestock handling activities are often found to be the second or third leading cause of on-farm injuries, with machinery and falls being cited as other leading causes. Among all livestock, cattle are responsible for the most injuries and fatalities on farms, and cattle-related nonfatal injuries have been shown to be some of the most costly, and result in more time off work than other injuries. Despite the fact that research has improved our understanding of cattle behavior and sensory functions, developed low-stress handling practices, and determined how facilities can be safer for workers and livestock, injury rates remain high. This project identified the types of equipment commonly used on beef farms, evaluated relationships between injuries and farm characteristics (such as herd size and equipment used), and assessed farmer perceptions of safety and obstacles to implementing changes. Most farms cited that they utilized equipment like alleyways (82.69%), a manual headgate (75.51%), a sorting/diverter gate (53.06%), and a manual squeeze chute (51.02%). However, it was found that having certain types of equipment had no influence on the likelihood of injuries. Herd size, on the other hand, was shown to be influential in that farms with larger than average herd size were shown to have a higher rate of injury. A final finding of this study was that farmers cited the cost of equipment, lack of necessity (their setup worked well already), and lack of time as being the main reasons they have not implemented changes on their operations. This study supports the idea that safe equipment and facilities are being implemented and used on most farms already, which suggests that the focus of future research should shift towards evaluating the influence that factors such as human behavior, handling practices, degree of training received, and training methods used have on the risk of worker injury.

Magister Philosophiae (Land and Agrarian Studies) - MPhil(LAS) / Municipal commonage has the potential to make a major contribution to land redistribution in South Africa. During the Apartheid era, land under the control of local government was leased out to commercial farmers at commercial rates, which ensured an important source of income for municipalities. Post-1994, municipalities have been tasked by the Department of Land Affairs with making land available to the previously disadvantaged and thus managing and administering the commonage for purposes of poverty alleviation.

Marginal communities living in semi-arid Namibia face significant challenges in sustaining rural livelihoods due to environmental degradation and poverty. Research has shown that livestock farming depends on rain-fed agriculture among other things, thus making communal farmers vulnerable to climate change in the future. Given this, it often makes sense for farmers to sell their livestock and explore alternative livelihood options. However, farmers in northcentral Namibia are reluctant to sell their livestock despite a noticeable temperature increase and rainfall decrease over the past forty years. This study analyses the barriers to selling livestock in the face of a drought in the Omusati region of north-central Namibia. The study was carried out in three villages namely Omahanene, Okathitukeengombe and Oshihau, in the north-central Omusati region of Namibia. Household livestock distribution, perceptions of climate change, barriers to the sale of livestock and alternative livelihood strategies from other semi-arid regions were explored among 30 households using semi-structured household interviews and a systematic literature review. Results from the study indicate that 80% of communal farmers predict future droughts in the region and able to recall climate change through frequent droughts, increasing temperatures and decreasing rainfall. Farmers claimed that these changes have affected their livestock numbers. However, several barriers including cultural beliefs, lack of financial security, access to information, lack of institutional support and lack of efficient markets hinder livestock sales. The study suggests that the imminent impact of climate change coupled with the reluctance to sell livestock will threaten food security in the future. The study argues that rural livelihood diversification strategies are critical to safeguarding sustainable livelihoods in the future, including those of communal livestock farmers specifically. Additionally, policy recommendations like access to credit through public and private funding, access to markets by providing transportation facilities, encouraging market participation by improving quality of grazing lands, increasing water availability, building veterinary facilities, employing extension officers and access to information through reliable channels can help build a sustainable future in the face of climate risks.

Cryptosporidium spp. is an oocyst-forming apicomplexan protozoan, which infects humans and a large variety of animals. Several species and genotypes are potentially zoonotic and ruminats are considered as an important source of infection. Pre-weaned calves are major hosts for zoonotic C. parvum, and show higher rates of infection than post-weaned or adult animals. Cryptosporidium infection has been demonstrated in a wide variety of wild animals, which may co tribute to environmental contamination. In sub-Saharan Africa, where the HIV infection prevalence is the highest in the world, high incidence of severe and even fatal Cryptosporidium infection have been reported in humans. This study investigated the epidemiology of Cryptosporidium spp. simultaneously in wildlife, indigenous cattle and young children living at the wildlife, livestock and human interface on the western boundary of the Kruger National Park (KNP) in Mpumalanga Province, South Africa. Initially, a pilot study was carried out to assess the zoonotic or anthroponotic importance of Cryptosporidium in diarrhoeic children in South Africa, representing the human group most likely to be infected. This geographically broad study involved hospitals from four provinces in South Africa. Stool samples from hospitalized diarrhoeic children from 0-1 year of age were analysed by microscopy (modified Ziehl-Neelsen (MZN) acid-fast staining) and molecular techniques: polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP) and sequencing. An overall prevalence of Cryptosporidium infection of 12.2% was revealed, mainly involving species of anthroponotic origin, such as C. hominis (76%) and C. parvum of anthroponotic nature (20%). Only one species of uncertain zoonotic importance (C. meleagridis) was detected in this study. These findings were in accordance with reports from sub-Saharan Africa (including South Africa), where anthroponotic species of Cryptosporidium were responsible for most infections in humans. The study then concentrated on the public health importance of cryptosporidiosis at the wildlife/livestock/human interface of the KNP. Cryptosporidium oocysts were detected in elephant, impala and buffalo samples collected in three different study areas of the KNP; two located close to the boundaries of the KNP and a third one in the centre of the KNP. The MZN staining technique and an immunofluorescent antibody (IFA) test were applied to identify oocysts from faecal samples. The prevalence detected with MZN was higher than that detected with IFA, however both tests found a higher prevalence in elephants (25.8% and 4.2%, respectively) compared to the other species. The prevalence of Cryptosporidium in buffalo was 5.5% and 1.4% with MZN and IFA, respectively, and 4.2% and 1.8% respectively in impala. In the two study areas adjacent to the fence of KNP, the combined prevalence was significantly higher compared to the area in the centre of the KNP. The agreement between the MZN staining technique and the IFA test was assessed for each wildlife species; the estimates of kappa suggested moderate agreement in buffalo and impala and fair to poor agreement in elephant. The above results of were analysed further by the use of molecular techniques in order to reveal the species and genotypes of the parasite in wildlife and in addition faecal samples collected from post-weaned calves. A questionnaire was also conducted among farmers to investigate observed contacts between cattle and wildlife species in grazing areas outside and inside the KNP. Four of the 241 wildlife samples were PCR-positive (2.8% each in impala and buffalo and of 0.0% in elephant) and sequencing revealed the presence of C. ubiquitum in two impala and one buffalo and C. bovis in one buffalo. Cryptosporidium ubiquitum has been commonly found in a large number of animals, including humans. Among calf samples, 8% (4/51) were PCR-positive and were identified as C. andersoni (2/4) and C. bovis (2/4). The probability of contact between cattle and wildlife outside the KNP, observed by farmers, was higher for buffalo (Pr=0.6) and impala (Pr=0.46) than for elephant (Pr=0.04). This suggests that the detection of C. bovis in both cattle and buffalo might be due to direct or indirect contact between these two species. The detection of C. ubiquitum in wildlife, with its zoonotic potential, suggests that Cryptosporidium may be of public health concern for people living at the interface. We further investigated the prevalence of Cryptosporidium infection in cattle and humans, this time targeting younger (pre-weaned) calves and children. Children <5 years were sampled at six rural clinics within the same interface and stool samples were screened by the MZN staining technique. All MZN-positive and suspicious samples of children and samples of 36 calves within the age of 0-4 months were analysed by nested PCR. Eight of the 143 children (5.6%) were positive on PCR, and sequencing identified predominantly C. hominis, while one sample was identified as C. meleagridis. Eleven of the 36 calf samples (30.5%) were PCR-positive and were identified as C. bovis and C. ryanae. Due to limited resources, molecular analysis could not be performed on more samples. Variables such as source of drinking water, age and contact with animals for children, were analysed as potential risk factors for humans and cattle; however, none were statistically significant. In conclusion, the prevalence of Cryptosporidium detected in human and wildlife was low compared to that reported in other studies in Africa. The species and genotypes detected in humans were predominantly of anthroponotic nature; however, the isolation of C. Ubiquitum from buffalo and impala shows that at least one species of zoonotic importance is present at the wildlife/livestock/human interface. The prevalence of HIV/AIDS in our study area is one of the highest worldwide; therefore the potential public health importance of this parasite should be investigated further. / Thesis (PhD)--University of Pretoria, 2013. / gm2013 / Production Animal Studies / unrestricted

Medusahead (Taeniatherum caput-medusae (L.) Nevski) is currently one of the biggest threats to rangelands and livestock operations in the Western US. High silica concentrations in medusahead contribute to its invasiveness. I developed a model to explain how silica is involved in the invasion process, and attempted to manipulate silica to increase use of the grass by livestock. Experiments were conducted to determine: 1) whether rotational grazing on established forages of improved nutritional quality would provide supplemental nutrients to increase cattle use of medusahead; 2) evaluate intake of and preference for medusahead treated with a glyphosate herbicide at different rates by sheep; and 3) evaluate intake and selection of medusahead by cattle by separating the effects of a glyphosate herbicide (Roundup®) from other chemicals in the formulation (salt, adjuvant). Additionally, experiments were conducted to 4) determine the nutritional value and digestibility of medusahead treated with Roundup® at different rates and at different plant particle sizes; and 5) determine if cattle grazing with trampling can increase seeding success on medusahead-invaded rangelands. Rotational grazing from supplemental pastures to medusahead-invaded pastures increased medusahead use by cattle during the second year of the study. Furthermore, glyphosate did not increase medusahead consumption in a choice between three glyphosate treatments, but did in a two-way choice test. Cattle grazed glyphosate-treated medusahead more than that of the non-treated grass and completely avoided the salt-treated grass. The active ingredient in a glyphosate herbicide increased consumption of medusahead while other ingredients in the herbicide (i.e., salt and adjuvant) had no influence on this choice. A smaller particle size increased the digestibility of medusahead compared to larger particle sizes. Glyphosate also increases digestibility, but not as much as particle size. Finally, cattle trampling did not help establish seeded plant species, and the seeding attempt was unsuccessful. Thus, grazing rotations between improved pastures and medusahead-infested rangeland, and the combined glyphosate application-grazing are new approaches for medusahead control, as they prepare a seed bed for revegetation and increase the nutritional quality of the grass for improved livestock nutrition.