Pathology of experimentally-induced, acute toxoplasmosis in macropods

SUMMARY Thirteen Tammar wallabies (Macropus eugenii) were dosed orally with 500, 1000 or 10 000 oocysts of Toxoplasma gondii, as part of a vaccination trial. Eleven animals died of acute toxoplasmosis 9 to 15 days after challenge. The lesions were similar in all animals, consisting of foci of necrosis and inflammation in the intestines, lymphoid tissue, adrenal cortex, heart, skeletal muscle and brain, and severe generalised pulmonary congestion and oedema. Free and intracellular tachyzoites of Toxoplasma were associated with the lesions. The remaining 2 animals had shown no signs of disease when euthanased four months after challenge. Small, focal, non-suppurative inflammatory lesions were seen in brain, heart and skeletal muscle of these animals and chronic Toxoplasma infection was confirmed by mouse inoculation.     

Seroprevalence of respiratory syncytial virus in free-ranging bighorn sheep

Sera from 187 (42%) of 447 free-ranging bighorn sheep (Ovis canadensis) in 9 western states had antibody titers to respiratory syncytial virus (RSV). Titers were from 1:5 to 1:640, as determined by the standard virus neutralization test. Results of the survey indicated that RSV is widespread in free-ranging bighorn sheep populations and that RSV may be an important factor in the bighorn sheep pneumonia-complex.     

Coccidiosis and cryptosporidiosis in sheep and goats

The protozoan diseases, coccidiosis and cryptosporidiosis, are important enteric diseases of sheep and goats, resulting in diarrhea, inefficient weight gains, and occasionally death. Coccidiosis is a widespread, serious economic disease affecting animals who are preweaned, recently weaned, or in unsanitary, stressful, or crowded conditions, as well as after entering feedlots. The Eimeria species in sheep and goats are relatively host specific. Control is accomplished through sanitation and by incorporating one of the modern coccidiostats, such as lasalocid or decoquinate, in feed or salt to ensure an intake of approximately 1 mg of drug per kg of body weight per day for at least 30 consecutive days. Prevention and control of coccidiosis results in significantly greater weight gains and production, whereas disease with or without treatment is likely to result in inefficient production and economic loss to the producer. Cryptosporidiosis, caused by Cryptosporidium parvum, is primarily a disease of lambs and kids less than 30 days of age and is usually a milder disease than coccidiosis. Infective oocysts are passed in feces and are transmitted by oral ingestion. Oocysts readily infect a variety of animals, including humans. Cryptosporidiosis is a prevalent disease in neonatal ruminants and in humans. Effective treatments are not available, but because the disease is usually mild and self-limited, supportive care, primarily hydration, is important. Control is strict sanitation and quarantine of sick animals. Disinfection of contaminated housing with ammonia or formalin will kill the oocysts. The cyst-forming coccidia diseases, toxoplasmosis and sarcocystosis, utilize two hosts in their life cycles: sheep or goats and carnivores. Abortions and reproductive failures are major manifestations of disease. Control is through elimination of carnivore feces from the premises through management.     

A national serological survey to verify Australia's freedom from porcine reproductive and respiratory syndrome

Objective To provide serological data to support Australia's claim of freedom from porcine reproductive and respiratory syndrome.
Design A national serological survey was designed to provide 99% confidence of detecting at least one infected pig herd in Australia, assuming that at least 5% of herds would have been exposed to porcine reproductive and respiratory syndrome virus and that at least 25% of the 'finisher' pigs in these herds would have antibodies to the virus.
Procedure A two-stage testing regime was used. All samples were tested with a commercially available enzyme-linked immunosorbent assay. If assay reactions were found, all samples from the herd were to be tested using the indirect immunofluorescence antibody assay.
Results Of the 875 samples from 163 herds from all States in Australia, there was some evidence of reactivity in only four samples from four herds on the enzyme-linked immunosorbent assay. Further testing using the indirect immunofluorescence antibody assay according to the study protocol demonstrated that the reactions were not due to the presence of specific porcine reproductive and respiratory syndrome virus antibodies in the sera.
Conclusion The results of this study support the view that Australian pigs are free of porcine reproductive and respiratory syndrome virus.     

A survey of beef cattle farmers in New Zealand,examining management practices of primiparous breeding heifers

AIM: To obtain an estimate of the incidence of assistance at calving in primiparous (first-calving) beef heifers and the prevalence of breeding heifers at 15 months of age in New Zealand in 2006,and to identify factors contributing to farmers' decisions regarding breeding strategies for heifers, using a survey of beef cattle farmers.

METHODS: A questionnaire was sent to farmers listed in a Massey University database and to members of selected breed societies, as well as published in an industry newspaper; 331 valid responses were received. Information was gathered on the age and number of primiparous heifers, number of heifers assisted, and the importance of various reasons for and against breeding heifers at 15 months of age. Respondents were also required to outline the criteria used for selecting bulls to join with heifers, and the strategies used to manage dystocia in primiparous heifers.

RESULTS: Sixty-five (95% CI=58–71)% of respondents had only 2-year-old primiparous heifers in 2006, whilst a further 11 (95% CI=8–16)% had both 2- and 3-year-old primiparous heifers. The mean reported incidence of assisted calving was 7.0 (95% CI=6.4–7.5)% for 2-year-old primiparous heifers and 1.7 (95% CI=1.2–2.2)% for 3-year-old primiparous heifers. The reported incidence of assistance at calving within individual herdsranged from 0 to 100% for 2-year-old heifers. Respondents with bull-breeding herds most commonly observed their primiparous 2-year-old heifers twice daily, whilst respondents with commercial herds most commonly observed them once daily during calving. The most important reason for breeding heifers at 15 months of age was “increased profit”, whereas the most important reason for not breeding them at that age was “concern about rebreeding performance of 2-year-old heifers”. Estimated breeding value (EBV) for birth weight was the factor considered most frequently when selecting bulls to join with maiden heifers; age of bull and body shape of bull were the next most frequently considered factors. Selection of an appropriate bull was the most common strategy used to manage dystocia in 2-year-old beef heifers.

CONCLUSIONS: The majority of respondents calved their heifers at 2 years of age, and “increased profit” was the primary motivator. Concern about the rebreeding performance of 2-year-old heifers was the most important reason among the remainder of respondents for not breeding heifers at 15 months of age. Dystocia in 2-year-old heifers was “not a problem” or “a minorproblem” in most herds, but there was much variation amongst herds.