The apxIC genes of the Actinobacillus pleuropneumoniae serovar 5 (SC-1), encoding the ApxI-activating proteins, was deleted by a method involving sucrose counter-selection. In this study, a mutant strain of A. pleuropneumoniae (SC-1) was constructed and named AapxIC/ ompP2. The mutant strain contained foreign DNA in the deletion site of ompP2 gene of Haemophilus parasuis. It showed no haemolytic activity and lower virulence of cytotoxicity in mice compared with the parent strain, and its safety and immunogenicity were also evaluated in mice. The LD50 data shown that the mutant strain was attenuated 30-fold, compared with the parent strain (LD50 of the mutant strain and parent strain in mice were determined to be 1.0 x 10(7) CFU and 3.5 x 10(5) CFU respectively). The mutant strain that was attenuated could secrete inactivated ApxIA RTX toxins with complete antigenicity and could be used as a candidate live vaccine strain against infections of A. pleuropneumoniae and H. parasuis.

Cestodes are parasitic flatworms that live in the digestive tract of vertebrates as adults and often in the liver, muscle, haemocoel, mesentery and brain of various animals as larval stages. To identify the cestodes infecting Clarias gariepinus Burchell, 1822 (sharptooth catfish) in the Vaal Dam, a total of 45 host specimens were collected with the aid of gill nets between October 2011, January and April 2012. The fish were sacrificed and examined for cestode parasites. Two adult cestodes, Tetracampos ciliotheca Wedl, 1861 (prevalence 86.7%, mean intensity = 15, n = 45) and Proteocephalus glanduligerus (Janicki, 1928) (prevalence 51.1%, mean intensity = 5, n = 45) were found in the intestines of the catfish. Both T. ciliotheca and P. glanduligerus are new locality records. There were statistically insignificant differences in the infection of the male and female C. gariepinu. Fish with standard length ranging from 40 cm - 54 cm (>3 years) had the highest prevalence and mean intensity while those ranging from 10 cm - 24 cm (< 1 year) had the lowest prevalence and mean intensity for both cestodes. The study highlights the importance of changing feeding habits of C. gariepinus with age on the prevalence and mean intensity of the two gastrointestinal cestode parasites.

A cross-sectional study was conducted to determine the prevalence of sub-clinical and clinical mastitis and the associated factors in cows from selected smallholder dairy farms in Zimbabwe. Physical examinations were conducted on all lactating cows for evidence of signs of clinical mastitis. Composite milk samples were collected from all lactating cows for bacterial culture and somatic cell counting. Cows were categorised as clinical if they exhibited clinical features of mastitis, or sub-clinical if no apparent signs were present but they had a positive bacterial isolation and a somatic cell count of at least 300 x 10³ cells/mL. Farm-level factors were obtained through a structured questionnaire. The association of mastitis and animal-and herd-level factors were analysed using logistic regression. A total of 584 animals from 73 farms were tested. Overall, 21.1% (123/584) had mastitis, 16.3% (95/584) had sub-clinical mastitis and 4.8% (28/584) had clinical mastitis. Herd-level prevalence was 49.3%. Coagulase-negative staphylococci (27.6%), Escherichia coli (25.2%), Staphylococcus aureus (16.3%), Klebsiella spp. (15.5%) and Streptococcus spp. (1.6%) were the most common isolates. In individual cows, pure dairy herds (OR = 6.3) and dairy crosses (OR = 3.1) were more likely to have mastitis compared to Mashona cows. Farms that used pre-milking teat dipping were I: associated with reduced mastitis prevalence. Further research is needed on the prevalence of mastitis and a comparison of data for both smallholder and commercial dairy farms in all regions of Zimbabwe should be undertaken.

Moraea pallida (yellow tulp) poisoning is economically the most important intoxication of livestock in South Africa. Poisoning varies according to locality, climatic conditions and growth stage of the plant. The primary objective of this study was to determine the concentration of the toxic principle, epoxyscillirosidine, in yellow tulp leaves and to ascertain I the variability of epoxyscillirosidine concentrations within and between different locations. A secondary objective was to utilise Geographic Information Systems in an attempt to explain the variability in toxicity. Flowering yellow tulp plants were collected at 26 sampling points across 20 districts of South Africa. The leaves of five plants per sampling point were extracted and submitted for liquid chromatography/mass spectrometry analysis. A large variation in mean epoxyscillirosidine concentrations, ranging from 3.32 µg/g - 238.27 µg/g, occurred I between different geographical regions. The epoxyscillirosidine concentrations also varied tremendously between individual plants (n = 5) collected at the same sampling point, with up to a 24 times difference between the lowest and highest concentration detected. No generalised I correlation between epoxyscillirosidine concentrations and soil elemental concentrations could be established. However, samples obtained from the north-eastern part of the sampling I region tended to have higher epoxyscillirosidine concentrations compared to samples obtained from the south-western part of the sampling region. Higher toxin concentrations in the northeast were associated with statistically significant higher soil concentrations of iron, bismuth, bromide, cadmium, chromium, rubidium, tellurium, thallium, titanium and zinc, whilst soil concentrations of strontium and soil pH, were significantly lower. This study corroborated the contention that epoxyscillirosidine concentration in yellow tulp fluctuates and may explain I the variability in toxicity.

The purpose of this study was to explore the audits, quality assurance (QA) programmes and legal frameworks used in selected abattoirs in Zimbabwe and slaughterhouse workers' perceptions on their effectiveness. Data on slaughterhouse workers was gathered through a self-completed questionnaire and additional information was obtained from slaughterhouse and government records. External auditing was conducted mainly by the Department of Veterinary Public Health with little contribution from third parties. Internal auditing was restricted to export abattoirs. The checklist used on auditing lacked objective assessment criteria and respondents cited several faults in the current audit system. Most respondents (> 50.0%) knew the purposes and benefits of audit and QA inspections. All export abattoirs had QA programmes such as hazard analysis critical control point and ISO 9001 (a standard used to certify businesses' quality management systems) but their implementation varied from minimal to nil. The main regulatory defect observed was lack of requirements for a QA programme. Audit and quality assurance communications to the selected abattoirs revealed a variety of non-compliances with most respondents revealing that corrective actions to audit (84.3%) and quality assurance (92.3%) shortfalls were not done. A high percentage of respondents indicated that training on quality (76.8%) and regulations (69.8%) was critical. Thus, it is imperative that these abattoirs develop a food safety management system comprising of QA programmes, a microbial assessment scheme, regulatory compliance, standard operating procedures, internal and external auditing and training of workers.

The insulin-like growth factor system (insulin-like growth factor 1, insulin-like growth factor 2, insulin-like growth factor 1 receptor, insulin-like growth factor 2 receptor and six insulinlike growth factor-binding proteins) and insulin are essential to muscle metabolism and most aspects of male and female reproduction. Insulin-like growth factor and insulin play important roles in the regulation of cell growth, differentiation and the maintenance of cell differentiation in mammals. In order to better understand the local factors that regulate equine physiology, such as muscle metabolism and reproduction (e.g., germ cell development and fertilisation), real-time reverse transcription polymerase chain reaction assays for quantification of equine insulin-like growth factor 1 receptor and insulin receptor messenger ribonucleic acid were developed. The assays were sensitive: 192 copies/µL and 891 copies/µL for insulin-like growth factor 1 receptor, messenger ribonucleic acid and insulin receptor respectively (95% limit of detection), and efficient: 1.01 for the insulin-like growth factor 1 receptor assay and 0.95 for the insulin receptor assay. The assays had a broad linear range of detection (seven logs for insulinlike growth factor 1 receptor and six logs for insulin receptor). This allowed for analysis of very small amounts of messenger ribonucleic acid. Low concentrations of both insulin-like growth factor 1 receptor and insulin receptor messenger ribonucleic acid were detected in endometrium, lung and spleen samples, whilst high concentrations were detected in heart, muscle and kidney samples, this was most likely due to the high level of glucose metabolism and glucose utilisation by these tissues. The assays developed for insulin-like growth factor 1 receptor and insulin receptor messenger ribonucleic acid expression have been shown to work on equine tissue and will contribute to the understanding of insulin and insulin-like growth factor 1 receptor physiology in the horse.

The use of haematological techniques to assess fish health is generally accepted. The aim of the current study was to determine selected haematological changes that occur in Clarias gariepinus (Burchell, 1822). infected with trypanosomes. Blood films were prepared according to standard techniques to confirm trypanosome infections and whole blood was collected, the serum and plasma separated, and prepared for albumin and total protein concentration analysis. Plasma albumin levels were significantly higher in infected wild caught fish than in uninfected wild caught fish and uninfected breeding stock. Serum albumin levels were significantly lower in infected wild caught fish when compared to uninfected breeding stock. The total plasma and serum protein levels were within the normal range for C. gariepinus, that is, 3 g - 6 g/100 mL. The total plasma protein levels varied significantly between the three groups. However, the total serum protein levels were only significantly different between uninfected breeding stock and uninfected wild caught fish, as well as uninfected breeding stock and infected wild caught fish. The total protein levels were significantly higher in infected wild caught fish than in the other groups, a possible indication of an infection or inflammatory host response.

Three each of 3-year-old Angus and Simmental heifers, surgically modified to collect bile, were used to measure the effects of pregnancy and breed on bile flow, biliary copper and zinc excretion and plasma copper and zinc concentrations. Bile copper excretion was significantly higher at 7-mo of pregnancy when samples from both breeds were pooled. From then onwards it declined to its lowest, one week post-partum. During pregnancy, plasma copper concentration increased slightly, reaching its highest level at 7-mo of pregnancy and then decreased slightly until full term. In pooled samples from both breeds, the correlation between increase in bile copper excretion and plasma copper concentration from 0 to 7-mo of pregnancy was high (r = 0.85) and significant (p < 0.05). Plasma zinc concentration decreased to the lowest level around 6-mo of pregnancy but increased thereafter until full term. In cows that were dried off one week after parturition, major shifts in bile and plasma copper and zinc parameters occurred at one week following and these coincided with a marked decline of bile flow and bile copper and zinc excretion. By 3-mo post-partum, biliary copper and zinc excretion and plasma copper and zinc concentrations had reached levels observed prior to pregnancy. When the data from all samples were pooled, the bile flow and bile copper excretion were significantly (p < 0.05) higher in Simmental, and plasma copper and zinc concentration higher in the Angus.