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.

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.

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.

Protection of Fasciola hepatica in the gut mucosa of immune rats is associated with infiltrates of eosinophils, IgG1 and IgG2a antibodies around the parasites.

We investigated the immune effector mechanisms that underlie protection against F. hepatica in the gut wall of immune rats, using (immuno)histochemistry. In the lamina propria of immune Wistar rats, four weeks after oral infection, frequencies of IgE-positive cells, eosinophils and mucosal mast cells were significantly increased, compared with naïve rats.

Tonsillar biopsy and PrPSc detection in the preclinical diagnosis of scrapie.

Preliminary findings have indicated that in naturally infected sheep, fully susceptible to scrapie (VRQ-homozygous), PrPSc can be detected in the tonsils approximately one year before the expected onset of clinical disease, whereas no immunostaining can be detected in animals with a semi-resistant genotype. This paper describes the technique for taking tonsillar biopsies from sheep and gives the results of the completed experiment. In another experiment PrPSc was detected even earlier in comparable VRQ-homozygous sheep born and raised in different surroundings.

Virulence, immunogenicity and reactivation of bovine herpesvirus 1 mutants with a deletion in the gC, gG, gI, gE, or in both the gI and gE gene.

Within the framework of developing a marker vaccine against bovine herpesvirus 1 (BHV1), several mutants with deletions in non-essential glycoprotein genes were constructed. Glycoprotein gC, gG, gI and gE single deletion mutants, a gI/gE double deletion mutant and a gE frame-shift mutant were made. The virulence and immunogenicity of these mutants were evaluated in specific-pathogen-free calves.

The immune response of cattle, persistently infected with noncytopathic BVDV, after superinfection with antigenically semi-homologous cytopathic BVDV.

Cattle persistently infected (PI) with noncytopathic (ncp) bovine virus diarrhea virus (BVDV) are at risk for developing fatal mucosal disease (MD), which is considered to occur after superinfection with antigenically homologous cytopathic (cp) BVDV. In this study, we intranasally inoculated four PI-animals, that were PI with 2 ncp BVDV strains with 10(5) TCID50 antigenically closely related cp BVDV. Two PI-animals were inoculated with 10(5) TCID50 ncp BVDV and one PI-animal, with virus free cell culture medium.

Studies on the efficacy of hyperbaric rendering procedures in inactivating bovine spongiform encephalopathy (BSE) and scrapie agents.

The efficacy of the procedures in use at the two rendering plants in the Netherlands was assessed on a laboratory-scale using procedures that simulated the pressure cooking part of the rendering process. A pool of bovine spongiform encephalopathy (BSE)-infected brainstem from the United Kingdom and a pool of scrapie-infected brainstem from Dutch sheep were used to spike the rendering materials. The mixtures were subjected to various time-temperature combinations of hyperbaric heat treatment related to the conditions used in Dutch rendering plants in the early 1990s, and to the combination of 20 minutes at 133 degrees C required by the EU Directive on rendering of 1996.

Comparison of DNA application methods to reduce BRSV shedding in cattle.

We compared the protection afforded by three different DNA application methods against bovine respiratory syncytial virus (BRSV) infection in cattle. A synthetic gene that codes for the G protein of BRSV was inserted into a eukaryotic vector and was used in the vaccine. Intradermal (i.

Effect of dietary vitamin E supplementation on pork quality.

The purpose of this experiment was to examine the effect of dietary vitamin E supplementation on pork quality, and in particular on colour stability. Crossbred pigs (n = 72) at a mean weight of 44 kg were assigned to one of two treatments. One group received, during a period of 84 days prior to slaughter, a tapioca based diet, which contained 8 mg vitamin E per kg feed.

Screening of a small set of random peptides: a new strategy to identify synthetic peptides that mimic epitopes.

Small diversity libraries, composed of 4550 synthetic dodecapeptides and 8000 synthetic tripeptides, have been used to identify sequences homologous to small linear and non-linear parts of epitopes. Here we report that synthetic peptides identified through alignment of dodecapeptides and tripeptides derived from these small libraries have, in direct ELISA and/or competitive ELISA, activities similar to that of peptides covering the native epitope and similar to that of peptides derived from large expression libraries composed of 10(6)-10(7) random peptides. This result was obtained with the monoclonal antibodies 6A.

Genetics of the interval from weaning to estrus in first-litter sows: correlated responses.

The objective of this study was to evaluate relationships between rebreeding performance and growth performance (n = 3,777 gilts) and rebreeding performance and reproductive performance (n = 2,242 sows). Our data were from a selection experiment for shorter intervals from weaning to estrus after the first parity (IWE), involving Dutch Landrace pigs, in which a selection line and a control line without selection were maintained for eight generations. Relationships were evaluated before and after transforming IWE to normal interval (NI; IWE < or = 7 d), prolonged interval (PI; IWE > 7 d), and incidence of a prolonged interval (INC).

Structural homology of the central conserved region of the attachment protein G of respiratory syncytial virus with the fourth subdomain of 55-kDa tumor necrosis factor receptor.

The attachment protein G of respiratory syncytial virus (RSV) has a modular architecture. The ectodomain of the protein comprises a small folded conserved region which is bounded by two mucin-like regions. In this study, a sequence and structural homology is described between this central conserved region of RSV-G and the fourth subdomain of the 55-kDa tumor necrosis factor receptor (TNFr).

Effect of pelvic suspension and cooking temperature on the tenderness of electrically stimulated and aged beef, assessed with shear and compression tests.

Electrically stimulated carcass sides of young bulls were suspended at 1 hr post mortem from the aitch bone (pelvic suspension; PS) and Achilles tendon (AT), respectively. After an ageing period of 14 days at 3 °C, shear force (SF) and compression (20 and 80% compression) tests of the Mm. longissimus lumborum et thoracis (LO) and semimembranosus (SM) were conducted in raw muscle and after heating for 1 hr at 55, 60, 65, 70 and 80 °C.

Inadequate anti-polysaccharide antibody responses in the chicken.

Chickens are notorious for the fact that they carry bacteria such as Salmonellae and Campylobacter, which can cause zoonoses by contamination of the end product, without hampering growth and development of the chicken itself. This carrier status can only been explained by the inability of the chickens immune system to eliminate the pathogen, this in turn being due to insufficient humoral responses towards the polysaccharides of the bacterial capsule. In a previous study, we demonstrated that in chickens a model thymus-independent type 2 (TI-2) polysaccharide antigen, trinitrophenylated Ficoll (TNP-Ficoll), hardly evokes a humoral immune response.

Identification of a conserved neutralization site in the first heptad repeat of the fusion protein of respiratory syncytial virus.

A large set of monoclonal antibodies (MAbs) directed against the fusion glycoprotein complex F1F2 of bovine respiratory syncytial virus (BRSV) and several polyclonal sera from infected or vaccinated animals were tested in Pepscan to locate linear epitopes on the F-protein. The polyclonal sera mapped to antigenic sites that correspond exactly to known antigenic sites on the F protein of human RSV. Only the neutralizing MAb 3 could be mapped with Pepscan.

Effect of monensin on milk production by Holstein and Jersey cows.

Effects of the administration of monensin via concentrates to dairy cows were studied in two trials. In one trial, 64 Holstein cows were assigned to four groups that received 0, 150, 300, or 450 mg/d of monensin from 5 to 24 wk postpartum. Milk production tended to increase (4.

Causes of inaccurate prediction of volatile fatty acids by simulation models of rumen function in lactating cows.

Extant mechanistic models of rumen functions are unable to predict the molar proportion of volatile fatty acids (VFA) accurately. In order to make these models useful in investigating theories on nutrient flows that go beyond the rumen, the representations adopted need to be improved. This theoretical study was directed at identifying what parts of a rumen model may be responsible for the inaccurate VFA prediction.

High-level expression of biologically active recombinant bovine follicle stimulating hormone in a baculovirus system.

Superovulation treatment of cows can benefit from the application of very pure recombinant bovine FSH (rbFSH), which is produced in nonmammalian cells. rbFSH is completely free of LH, and therefore can possibly reduce the variability in the results of superovulation. Furthermore, it does not contain brain-tissue-derived proteins and, when produced under serum-free conditions, it is free of other mammalian substances or potentially infectious material.

Parasites of stomach and small intestine of 70 horses slaughtered in The Netherlands.

The prevalence of metazoan parasites in the stomach and small intestine was investigated in 70 horses slaughtered in the period February 1994-July 1994. Most horses were young (1.5-3 years) and in good condition.

Studies of feather pecking in poultry.

Feather pecking and cannibalism are obviously detrimental to birds' welfare. Moreover, the introduction of alternatives to battery cage housing of laying hens is seriously hampered by these behaviours. Our experimental work reviewed here supports the hypothesis that feather pecking evolves as redirected ground pecking.