Aujeszky's disease in a horse

A horse with neurological signs and severe meningoencephalitis caused by Aujeszky's disease is described. The diagnosis was established by immunohistochemistry, DNA-in situ hybridization and serological tests. Aujeszky's disease virus antigen and Aujeszky's disease viral DNA were detected in neurons of the cerebrum. In the serum of the horse antibodies against Aujeszky's disease virus were detected in a virus neutralization test, in a blocking ELISA which specifically detects antibodies against the glycoprotein I (Ig) of the virus, in an indirect double sandwich ELISA and with colloidal gold immunoelectron microscopy which detects antibodies directed against the envelope and nucleocapsid of the virus. Intranasal infection of two points with a high dose of Aujeszky's disease virus caused very wild and transient signs. Although the experimental infection induced virus neutralizing antibodies, it failed to induce gI specific antibodies.     

Assessment of the quality of tests for the detection of antibodies to Aujeszky's disease virus glycoprotein gE in a target population by the use of receiver operating characteristic curves

The performance of tests for the detection of antibodies to Aujeszky's disease virus glycoprotein E (ge) in a target population was evaluated by constructing and analysing receiver operating characteristic (roc) curves. These curves assess the discriminating ability of a test over the entire range of test signals. The advantages of applying the analysis to a sample of the target population (all commercial pigs in the Netherlands), as compared to using a panel of test sera, are that the estimates of sensitivity and specificity, the comparisons between tests and the choices of the cut-off values are all relevant for the target population. The results of a gE-elisa in colostrum (test A) and in a single droplet of whole blood (test B) were compared with the results obtained with the same elisa in serum (gold standard). The area under the ROC curve, which is a quantitative measure of test performance, was significantly (P<0·01) smaller with test A than test B or the gold standard, indicating that test B performed better than test A. No significant difference was observed between test B and the gold standard.     

Manipulation of Domestic Animal Embryos and Implications for Development

Assisted reproductive technologies, as applied to domestic animals, can exert both novel and wide‐ranging influences on the development, viability and welfare of offspring. Some of the changes are evident immediately or soon after the time at which a manipulative procedure is carried out, while other changes may not be evident until later in development or, perhaps, may remain undetected throughout an animal's lifetime. The present review explores some of the consequences – in terms of foetal, placental, neonatal and post‐natal effects – of exposing embryos of cattle, sheep and other species to in vitro culture per se or, during culture, to physically invasive technologies including gene injection and nuclear transfer. The innate sensitivity of oocytes and recently fertilized eggs to their in vitro environment is illustrated by an examination of the later developmental repercussions resulting from apparently innocuous choices related to in vitro culture medium formulations. In contrast, an inherent resilience and paradoxical readiness to resume development following the traumas of nuclear transfer procedures is also in evidence. The extent to which assisted reproductive technologies will succeed, where relevant, in the domestic animal sector will be influenced by our appreciation of embryo requirements, for both short‐ and long‐term developmental fitness, during their earliest developmental stages. Evidence of species‐specific needs is testimony to the challenges ahead. Ultimately, our ability and inclination to resolve the limitations associated with current procedures will probably be greatly enhanced if predictive indicators (genetic, epigenetic or functional markers) of later developmental fitness can be identified.     

Epidemiological study of bovine respiratory syncytial virus infections in calves: influence of maternal antibodies on the outcome of disease

A prospective epidemiological survey on bovine respiratory syncytial virus (BRSV) infections in calves was carried out on 21 dairy farms during one BRSV epidemic season. Special attention was paid to the role of maternal antibodies. On 15 farms the spread of the virus was demonstrated during the investigation period and on eight farms this was accompanied by an outbreak of acute respiratory disease. Disease seldom occurred in calves younger than two weeks old and the most severe disease was observed in calves from one to three months old. Although maternal antibodies did not effectively prevent the disease, both the incidence and severity of disease were inversely related to the level of specific maternal antibodies. Two serodiagnostic techniques were compared. In calves older than three months from herds with disease outbreaks associated with bovine respiratory syncytial virus the diagnosis was established in 80 per cent of the animals by an increase in IgG titre against BRSV and in 77 per cent by the detection of BRSV specific IgM. In comparison, only 10 per cent of the calves younger than three months were positive by IgG serodiagnosis, and 51 per cent by IgM serodiagnosis. On farms where the spread of the virus was accompanied by an outbreak of clinical disease more calves were present, a higher proportion of the calves was younger than three months, and calves of all ages were more often housed together.     

Ovine keratoconjunctivitis experimentally induced by instillation of Mycoplasma conjunctivae

Five sheep, free from Mycoplasma conjunctivae and ocular Chlamydia infection, were experimentally inoculated with M. conjunctivae and five more sheep were exposed to the infection by contact. Keratoconjunctivitis developed in all ten sheep. As in natural outbreaks of infectious keratoconjunctivitis (IKC), clinical signs were generally moderate and transient, and recurred in some sheep. M. conjunctivae was detected throughout the 53-day observation period. Clinical diagnosis was confirmed by histopathologic examination of three sheep. Moraxella ovis, found in six of the ten sheep before the start of the experiment, appeared to play no etiologic role in the development of IKC.     

Immunoglobulin M-specific enzyme-linked immunosorbent assay for serodiagnosis of bovine respiratory syncytial virus infections

An antibody-capture enzyme-linked immunosorbent assay (ELISA) for detection of immunoglobulin (Ig) M antibodies to bovine respiratory syncytial virus (BRSV) in cattle was developed. Monoclonal antibody to bovine IgM was used as the catching antibody. The IgM-ELISA was used, as well as a BRSV-specific IgG ELISA to determine the kinetics of IgM and IgG antibody responses to BRSV infections in cattle. High IgM and IgG antibody titers developed after naturally occurring or induced BRSV infection of calves (6 to 7 months old). Induced infection resulted in an IgM response that was first detectable at postinoculation day (PID) 11 reached a maximum at PID 13, and became undetectable again about PID 28. An IgG response also was detected by PID 11. However, a maximum response was not reached before PID 23, and titers remained high (until PID 80). In naturally occurring infection, IgM and IgG responses in calves were observed in the acute phase of epizootics of respiratory tract disease. Patterns of IgM and IgG response curves were similar to those observed in experimentally infected calves. The involvement of BRSV in an epizootic of respiratory tract disease in 8 calves (2 to 3 weeks old) was demonstrated by the detection of BRSV in several lung lavage samples. All calves had existing IgG antibodies to BRSV which were interpreted to be maternally derived. None of the calves responded with an increase in IgG antibody titer. However, a weak but distinct BRSV IgM antibody response occurred in 6 calves.(ABSTRACT TRUNCATED AT 250 WORDS)     

Estimating the level of disease risk and biosecurity on commercial poultry farms in New Zealand

ABSTRACT

Aims: To collect baseline data on the contact risk pathways and biosecurity practices of commercial poultry farms in New Zealand, investigate the relationship between the farm-level disease contact risks and biosecurity practices, and identify important poultry health concerns of producers.

Methods: A cross-sectional survey of all registered New Zealand commercial poultry operations was conducted in 2016 collecting information on farm demographics, biosecurity practices, and contact risk pathways. Survey responses were used to generate an unweighted subjective disease risk score based on eight risk criteria and a subjective biosecurity score based on the frequency with which producers reported implementing seven biosecurity measures. Producer opinions towards poultry health issues were also determined.

Results: Responses to the survey response were obtained from 120/414 (29.0%) producers, including 57/157 (36.3%) broiler, 33/169 (19.5%) layer, 24/55 (44%) breeder, and 6/32 (19%) other poultry production types. Median disease risk scores differed between production types (p?<?0.001) and were lowest for breeder enterprises. The greatest risk for layer and broiler enterprises was from the potential movement of employees between sheds, and for breeder enterprises was the on- and off-farm movement of goods and services. Median biosecurity scores also differed between production types (p?<?0.001), and were highest for breeder and broiler enterprises. Across all sectors there was no statistical correlation between biosecurity scores and disease risk scores. Producers showed a high level of concern over effectively managing biosecurity measures.

Conclusions: The uptake of biosecurity measures in the commercial poultry farms surveyed was highly variable, with some having very low scores despite significant potential disease contact risks. This may be related to the low prevalence or absence of many important infectious poultry diseases in New Zealand leading farmers to believe there is a limited need to maintain good biosecurity as well as farmer uncertainty around the efficacy of different biosecurity measures. Further research is needed to understand barriers towards biosecurity adoption including evaluating the cost-effectiveness of biosecurity interventions.     

Role of Fatty Acids in Energy Provision During Oocyte Maturation and Early Embryo Development

While much is known about the metabolism of exogenous nutrients such as glucose, lactate, pyruvate, amino acids by oocytes and pre-implantation mammalian embryos, the role of endogenous stores, particularly lipid, has been largely overlooked. The presence of lipid within oocytes and early embryos has been long known, and comparisons between species indicate that the amounts and types of lipid present vary considerably. Large amounts of intracellular lipid can compromise the success of cryopreservation and the removal of such lipid has been the subject of considerable effort. In this review, we present evidence that strongly suggests a metabolic role for lipid, specifically with regard to energy provision, in the late-stage oocyte and the pre-implantation embryo. We focus initially on oxygen consumption as a global indicator of metabolic activity, before reviewing different approaches that either have been designed to investigate directly, or have revealed indirectly the role of endogenous lipid in energy generation. These fall under five headings: (i) fatty acid oxidation; (ii) inhibition of triglyceride oxidation; (iii) culture in the absence of exogenous substrates; (iv) cytoplasmic organization; and (v) delipidation. On the basis of the data derived from these studies, we conclude that there is strong evidence for the utilization of endogenous lipid as an energy substrate by oocytes and early embryos.