Time course of the porcine cellular and humoral immune responses in vivo against pseudorabies virus after inoculation and challenge: significance of in vitro antigenic restimulation.

We investigated the time course of porcine cellular and humoral immune responses against pseudorabies virus (PRV) after pigs were inoculated with PRV gE(-) mutant strain M141 and challenged with wild-type virus NIA-3. Peripheral blood mononuclear cells (PBMC) were isolated from blood samples; half were used directly and half were restimulated with PRV in vitro before use in a cytolytic assay. We determined time course and extent of PRV-specific lymphoproliferative and cytolytic response.

Estimation of the biological activity (potency) of batches of brucellin prepared from a mucoid strain of Brucella abortus.

A study was conducted to determine the repeatability of a procedure used to prepare brucellin from a mucoid strain of Brucella abortus, and to determine the biological activity of those brucellins. The brucellins were standardized to contain 1 mg protein/ml, and their potency was estimated according to the European pharmacopoeia norm for tuberculin. Estimation of the potency was done in cattle that have been sensitized with living or killed brucellae.

An infectious cDNA clone of porcine reproductive and respiratory syndrome virus.

A plasmid containing a full-length cDNA copy of the Lelystad virus isolate (LV) of porcine reproductive and respiratory syndrome virus was constructed. When RNA that was transcribed in vitro from this full-length cDNA clone was transfected to BHK-21 cells, infectious LV was produced and secreted. The virus was rescued by passage to porcine alveolar lung macrophages or CL2621 cells.

Optimizing pure line breeding strategies utilizing reproductive technologies.

The development of new reproductive techniques has had a great effect on schemes for dairy cattle improvement; AI resulted in progeny-testing schemes, and, more recently, multiple ovulation and embryo transfer has resulted in nucleus breeding schemes. In traditional breeding schemes, the use of multiple ovulation and embryo transfer resulted in only small increases of genetic gains because the selection intensity of bull dams was already high, but the selection intensity of cows in nucleus breeding schemes increased considerably. This increase makes nucleus schemes very competitive, especially when in vitro maturation and fertilization is used to increase female reproductive rates further.

Effects of simulated lairage conditions on the physiology and behaviour of pigs.

The responses of pigs to being driven and mixed together in lairage were investigated. Five groups of six and five groups of seven 70 kg pigs were transported for 40 minutes on a lorry and then subjected to one of the following treatments: two groups were driven down a passage; four groups (A to D) were mixed together for one hour (A and B together, and C and D together); and, four groups were driven down the passage and then mixed ('combined treatment'). The pigs' behaviour was recorded, skin damage was scored and saliva samples were taken for analysis of cortisol.

Antigen detection in vivo after immunization with different presentation forms of rabies virus antigen, II. Cellular, but not humoral, systemic immune responses against rabies virus immune-stimulating complexes are macrophage dependent.

In this paper we describe the effect of depletion of splenic macrophages on the uptake, and immune response against, different formulations of rabies virus antigen. Splenic macrophages were removed by intravenous injection with clodronate liposomes. beta-propiolacton inactivated rabies virus (RV-BPL) and immune-stimulating complexes (iscom) containing these antigens were given to macrophage-depleted and control mice.

Starch supplementation of grass harvested at two stages of maturity prior to ensiling: intake, digestion, and degradability by dairy cows.

The effects of the maturity of grass prior to ensiling and the supplementation of starch to grass silage on apparent digestibility, degradability, rumen content, and feed intake by dairy cows were investigated using a Latin square design. Treatments were silages from early or late cut grass with or without 4 kg of supplemental flaked corn starch. The silage from early cut grass contained more N and sugars than did the silage from late cut grass but was lower in neutral detergent fiber (NDF).

Effects of strawbedding on physiological responses to stressors and behavior in growing pigs.

To study the effects of environmental enrichment on physiological responses to stressors and behavior in growing pigs, pigs were housed in either a poor environment (standard farrowing pens followed by standard rearing and fattening pens) or in an enriched environment (larger farrowing pens followed by larger rearing and fattening pens, provision of straw). Body temperature, heart rate and salivary cortisol were measured during baseline conditions and in response to relocation, isolation and restraint. Pigs housed in the poor environment performed more manipulative social behavior directed to penmates than pigs housed in the enriched environment.

Effects of regular moving and handling on the behavioral and physiological responses of pigs to preslaughter treatment and consequences for subsequent meat quality.

The effects of regular moving and handling during the finishing period on behavioral and physiological responses of pigs during preslaughter treatment and consequences for meat quality were studied. From the age of 10 wk onward, 144 pigs were housed in groups of four (two gilts and two castrates) and subjected to one of the following treatments. The Environment treatment allowed pigs to move freely for 8 min outside their home pen.

Impedance recordings to determine change in extracellular volume in the brain following cardiac arrest in broiler chickens.

The present study describes a method to determine the onset and development of brain damage in broiler chickens. Exsanguination disrupts the brain metabolism and causes the brain to become ischemic. Energy-requiring systems in the cell membrane fail, which results in an ionic shift over the membrane, accompanied by a water influx into the cell.

In vitro inhibition of the bioactivity of follicle-stimulating hormone by antisera against a peptide representing part of the FSH-receptor.

The aim of the present work was to define an FSH receptor (FSHR) peptide that can induce antibodies that will inhibit the bioactivity of FSH. Therefore, the hFSHR sequence was aligned with that of all other known G-protein coupled receptors. An area with increased sequence homology was identified between the FSH-, LH-, TSH receptors, the C5a receptor and the IL8 receptor.

Further observations on the impact of a veterinary programme in Afghanistan on seasonal livestock mortality.

This paper reports further results of a two year livestock mortality survey in Afghanistan, where a war of more than a decade had completely disrupted the veterinary field services. A questionnaire-based survey to measure the impact of a veterinary field programme indicated that average annual mortality in cattle, sheep, and goats was substantially lower in districts that received veterinary services (covered districts) than in districts without any veterinary services (control districts). The impact of the programme varies according to the season and the age group of the animals involved.

Location of induction and expression of protective immunity against Fasciola hepatica at the gut level: a study using an ex vivo infection model with ligated gut segments.

In the present study, we investigated the site in the host where protective gut immunity to Fasciola hepatica is induced and expressed, following the infection route of the parasite. Expression of protection was studied in ex vivo gut segments with intact blood and lymph supply that were prepared at different locations along the entire length of the small and large intestine. Four weeks after oral infection, significant protection was detected in the duodenum, upper jejunum, midjejunum, and ileum.

Critical factors affecting the diagnostic reliability of enzyme-linked immunosorbent assay formats.

This paper aims to evaluate different formats of the enzyme-linked immunosorbent assays (ELISAs) for detection of virus-specific antibodies and focuses on factors that may influence the diagnostic reliability of such tests. Newly developed and well-established ELISAs for detection of infections of bovine herpesvirus 1 (BHV1), bovine respiratory syncytial virus (BRSV), classical swine fever virus (CSFV), pseudorabies virus (PRV) and bovine viral diarrhoea virus (BVDV) are used as examples. Differences between competitive and non-competitive ELISAs are described, with special reference to the influence of the antigen, the conjugated antibody and the test sample on the test results.

Management practices and use of anthelmintics on dairy cattle farms in The Netherlands: results of a questionnaire survey.

In December 1996, a questionnaire about farm management and parasite control measures in calves was sent to 956 randomly chosen dairy cattle farmers in The Netherlands. Another 150 farmers in the vicinity of Deventer who had vaccinated their calves in 1995 against lungworm were approached with the same questions. Our object was to investigate the consequences on worm control of the withdrawal of the lungworm vaccine from the market for reasons of possible BSE contamination of the vaccine.

A novel ex vivo rat infection model to study protective immunity against Fasciola hepatica at the gut level.

We describe an ex vivo rat infection model to study protective immunity against Fasciola hepatica at the gut level. An exact number of newly excysted juveniles (NEJs) was injected into a gut segment with an intact blood supply and which was still attached to a live anaesthetized rat. NEJs that penetrated the gut wall during the following 6 h were recovered from a beaker filled with medium and were counted under a microscope.

Silent memory induction in maternal immune young animals.

Maternal immunity was shown to be an effector mechanism which does not include transfer of memory. 'Boosting' of maternal immunity by vaccination was not effective. Transferred maternal immunity negatively interfered with the induction of optimal protection by vaccination.

Prevention of diarrhoea using pathogen specific monoclonal antibodies in an experimental enterotoxigenic E. coli infection in germfree piglets.

In the present study we describe the effect of oral application of mAB specific for ETEC F4ac fimbriae in an experimental ETEC challenge model in neonatal germfree piglets. The results show that mAB, specific for different F4ac epitopes protect animals against ETEC specific pathology. Moreover, the results show that protection is independent of F4ac epitope specificity.

The F41 adhesin of enterotoxigenic Escherichia coli: inhibition of adhesion by monoclonal antibodies.

The anti-adhesive properties of 23 specific monoclonal antibodies (MAbs) against the F41 adhesive fimbrial antigen of enterotoxigenic Escherichia coli (ETEC) were studied in brush border adhesion inhibition tests and haemag-glutination inhibition tests with four F41-positive E. coli strains and purified F41 antigen. These MAbs recognize five epitope clusters, F41-1 to F41-5.

Weaning piglets as a model for studying pathophysiology of diarrhea.

During fifty years weaning age of piglets decreased from, in former days, ten to twelve weeks till, nowadays, three to five weeks. Early weaned piglets frequently have diarrhea. When piglets had diarrhea after weaning, enterotoxigenic E.

Maintenance of Brucella abortus-free herds: a review with emphasis on the epidemiology and the problems in diagnosing brucellosis in areas of low prevalence.

This review covers some epidemiological aspects that allow Brucella to survive, spread, and maintain itself in the environment. Because the success of maintaining Brucella-free herds is determined by the efficiency of the serological tests to detect a single infected animal the limitations of the traditional serological tests are emphasized. Serological tests cannot differentiate between cattle infected with Brucella and cattle infected with microorganisms that serologically cross-react with B.

New GnRH-like peptide construct to optimize efficient immunocastration of male pigs by immunoneutralization of GnRH.

Castration of male pigs is routinely performed in order to prevent the occurrence of boar taint in pig carcasses. However, boar taint can also be eliminated by immunological castration using a synthetic peptide vaccine against GnRH. For pig farming, to make immunocastration a feasible alternative method to surgical castration, the composition of the vaccine has to be not only reliable and effective but also cost-efficient and safe.

Perspectives of future feed information based on energy and nutrient availability.

The need for improvement of feed information in future is discussed from the perspective for implementation in practice. Weaknesses of the current feed evaluation systems, energy systems in particular, are described: prediction of voluntary feed intake, additivity of digestibilities of individual feedstuffs and dynamics of digestion, efficiency of utilization of energy and variation in maintenance requirements. A brief inventory of models to quantify energy and nutrient metabolism by farm animals is followed by an overview of aspects required to fulfill the demands for a nutrient-oriented feed evaluation.