Effect of the fungicide imazalil on hepatic microsomal cytochrome P-450 and cytochrome P-450 dependent activities in the Bobwhite quail (Colinus virginianus)

Bobwhite quails were treated with imazalil for 8 weeks. The fungicide was given admixed in the food at 0, 100, 300, 500 and 1000 mg kg^?1. Even at the highest dose tested, imazalil did not affect the liver weight or the hepatic microsomal protein content. In treated quails, no significant induction of cytochrome P-450 or NADPH-cytochrome c-reductase activity was observed. Furthermore, imazalil did not induce or inhibit 7-ethoxyresorufin or 7-ethoxycoumarin O-deethylase in quail microsomes. Only a slight but significant increase by 35% and 49% in aniline hydroxylase activity was measured for the 500- and 1000-mg kg^?1 dose levels, respectively. After a drug-free period of one week, aniline hydroxylase activity returned to control values, indicating that the effect was fully reversible. It is concluded that imazalil does not induce or inhibit drug-metabolizing enzymes in the quail, even at doses which exceed by far the maximum levels currently used to dress seed under field conditions (100 mg kg^?1).     

Components of resistance to late blight (Phytophthora infestans) in eight South AmericanSolanum species

Four components of partial resistance toPhytophthora infestans were measured after inoculation in the greenhouse and in the field ofSolanum arnezii x hondelmannii, S. berthaultii, S. circaeifolium, S. leptophyes, S. microdontum, S. sparsipilum, S. sucrense andS. vernei, and four hybrid progenies ofS. microdontum withS. tuberosum. The four components were infection efficiency, lesion growth rate, generation time and sporulation capacity. The results were compared with resistance ratings derived from field experiments, and with observations made on the potato cultivars Bintje, Bildstar, Libertas and Pimpernel. Genetic variation for all components was found, while the relative importance of the components of partial resistance appeared to vary between the species. InS. microdontum, generation time, infection efficiency and lesion growth rate, and inS. tuberosum infection efficiency, lesion growth rate and sporulation capacity appeared positively associated, but in other species no such association was found. A strong hypersensitive reaction, the expression of which appeared to depend on environmental conditions, was found inS. microdontum. ForS. berthaultii, infection efficiency appeared to be the main resistance component.Abbreviations ADPC area under the disease progress curve - IE infection efficiency - LGR lesion growth rate - GT generation time - SC sporulation capacity     

Field efficacy of a combined use of Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae vaccines in growing pigs

The effectiveness of simultaneous administration of commercial Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae vaccines was tested in an indoor commercial piggery which had experienced continuing respiratory-disease problems confirmed as due to both of these pathogens. Piglets were randomly assigned in equal numbers to vaccination and control groups, and each vaccine was administered at a separate site to assigned piglets at two and four weeks of age. Live weight of vaccinates immediately prior to slaughter was 2.49 kg higher (p = 0.04) than for controls at equal mean slaughter age of 132 days. Average daily gain (ADG) from 16 weeks to slaughter of vaccinates was also significantly higher (33 g/day) than in controls (p = 0.05). Daily gain was not significantly different in younger age groups. Active enzootic pneumonia lesions were more likely in control than in vaccinated pigs. There were no significant differences between vaccination groups with regard to severity of pleurisy or presence of pleuropneumonia lesions at slaughter. Log-linear modelling was used to test the statistical association between vaccination, enzootic pneumonia lesions, pleurisy lesions and pleuropneumonia lesions. It showed a reduction in the severity of enzootic pneumonia lesions for vaccinated pigs, and the presence of pleuropneumonia lesions increased the likelihood of pleurisy lesions. No other association was significant, and no evidence of synergy between the vaccines in influencing lesion severity for pleuropneumonia was detected (within the limitations set by the trial design).     

Evaluation of pseudorabies viral antigens in the agar gel immunodiffusion test.

Procedures designed to extract pseudorabies viral (PRV) antigens from PRV-infected tissue cultures were investigated to determine whether differences in extraction method had an effect upon the final concentrated antigenic product. All four of the preparations made from PRV-infected tissue culture cells (trypsin extract and disrupted cells) or entire PRV-infected cultures (polysorbate 80 extract and (NH4)2SO4 precipitate) contained relatively large amounts of the same antigen, whereas cell-free PRV-infected tissue culture fluids did not contain significant amounts of this antigen. Specific antibody directed against this antigen was present in all PRV antisera tested. Two other antigens were observed in some of the preparations, but PRV antisera varied in their ability to precipitate with these antigens. Therefore, the number of precipitation lines observed in agar gel immunodiffusion between PRV preparations and PRV-positive antisera depended both upon the extraction method used to obtain the antigen and upon the specificity of the selected antiserum.     

Gastric Hypochlorhydria in Ferret Distemper

In the present investigation 42 female ferrets were studied in regard to the influence of canine distemper in this species on gastric acid secretion. A total of fifteen naturally-infected and 27 non-infected ferrets were fasted and pylorus-ligated, and were either injected with corticosterone (10 or 50 mg/kg, s.c. one injection/day for 4 days) suspended in corn oil, injected with corn oil, on non-injected. Prior to autopsy blood samples were acquired for corticosterone analysis, and at autopsy the volume, pH, free and combined acidity of the gastric contents were evaluated.     

An analysis of the performance characteristics of serological tests for the diagnosis of Neospora caninum infection in cattle

AIMS: To analyse the performance characteristics (sensitivity/specificity) of two enzyme-linked immunosorbent assays (ELISA) against the indirect fluorescent antibody test (IFAT). METHODS: A total of 1199 sera were tested in two ELISAs and the IFAT and results analysed utilising software that performed a receiver-operating characteristic (ROC) analysis. RESULTS: Sensitivity and specificity for the two ELISAs were calculated for a range of different cut-offs. Minimal misclassification was achieved at cut-offs that, in the case of the Central Animal Health Laboratory (CAHL)-ELISA were in line with previously published cut-off values. In the case of the IDEXX-ELISA lower cut-off values than suggested by the manufacturer were calculated. CONCLUSIONS: ROC-analysis resulted in optimised, as compared to the IFAT, cut-off thresholds for the CAHL and IDEXX-ELISA which can be further adjusted depending on the purpose of the investigation.     

Within-farm spread of classical swine fever virus--a blueprint for a stochastic simulation model

A stochastic simulation model to investigate the transmission of classical swine fever (CSF) virus within an infected farm is described. The model is structured according to the processes that occur within and between management groups (pig units or houses). It uses the individual pig as the unit of interest and estimates the number of animals in the states 'susceptible', 'infected', 'infectious', and 'removed' for each day of the disease incident. Probabilities are assigned to the transitions between states. The probability of a pig becoming infected is made dependent on the probability of contact between a susceptible and an infectious pig as well as the probability of transmission. The more pigs become infected in one unit, the more likely is subsequent spread to another management group on the farm. Ultimately, the probability that a shipment of pigs from the farm will include at least one infected pig can be estimated in order to identify high-risk movements during a CSF epidemic. The model results were compared with experimental data on CSF transmission within one pig unit (management group). It could be shown that the model was capable of reproducing the experimentally observed infection and mortality rates. To improve the input parameters and for further model validation, more experimental data and field data from CSF outbreaks are needed.     

A cross-sectional study of risk factors for obesity in cats in New Zealand

This study was done to identify risk factors for obesity in an urban cat population in New Zealand. A door-to-door survey (conducted within the city limits of Palmerston North) obtained information on the diet, health and behaviour of 202 cats. One hundred and eighty-two of these cats were weighed and their back and leg lengths were measured. The interviewer's assessment of the body condition of each cat was the dependent variable used in this study. Variables that were identified as significant (p< or =0.1) following univariable analysis were grouped into one of the three models for stepwise logistic multiple regression (one each for cat characteristics, environmental and management variables and feeding variables). A combined logistic-regression analysis was performed on the significant variables identified from the three component models. In the combined model, only three variables were significant: the presence of dogs in a household (decreased odds of obesity), longer leg length and owners underestimating cats' body condition (both increased odds).     

PrP genotype and lamb birth weight in a scrapie-free environment: Is there an association?

The National Scrapie Plan (NSP) for Great Britain includes selective breeding programmes. These aim to reduce the frequencies of the ovine prion protein (PrP) genotypes at high risk of developing clinical disease (principally those containing the VRQ allele) within the national flock, and select for the low-risk ARR-containing genotypes. The aim of this work was to use available data from embryo transfer programmes in guaranteed scrapie-free environments to investigate whether there was a difference in lamb birth weight associated with the lamb's PrP genotype, which might affect survival. The first analysis utilised data from 355 Cheviot lambs born between 2001 and 2004. The analysis was then repeated using a larger data set of 737 Cheviot, Dorset and Suffolk lambs born between 1999 and 2003. The most important determinants of mean lamb birth weight were litter size, sex and recipient ewe breed, plus lamb breed in the three breed analysis. In both analyses the effects of all these variables are consistent and of the same order of magnitude. In the first analysis there was evidence for an apparent increase in mean lamb birth weight for the ARR-containing genotypes of 0.3 kg (95% C.I. 0.1–0.5 kg). Whereas, in the second data set there was evidence for a decrease in mean lamb birth weight for the VRQ-containing genotypes of − 0.6 kg (95% C.I. − 0.8 to − 0.4 kg). This had been masked in the first analysis by the categorisation of these genotypes with the ARQ/ARQ genotype. Within these flocks, in a scrapie-free environment, neither finding provides support for concerns that selection for low risk ARR-containing genotypes would be detrimental to lamb birth weight, which is considered to be the most important determinant of lamb survival. Extension of this work into field flocks, where scrapie-status cannot be easily assured, will require the collection of sufficient data to adjust for known direct effects as well as any additional potential confounding effects.