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J C Bosch

Publications and source records attributed to J C Bosch.

12 recordsLinked to original sources
PubMed2006

Ways to improve the biosecurity of bovine semen.

Semen production and trade is a worldwide industry. A framework, based on international standards is awaiting international and national regulation. In the perspective of biosecurity of the final product, critical notes can be made according to the semen production regulation and product safety. Process description brings the obligatory health standards for the production bulls, collection and processing of semen, identification, registration, worldwide distribution and insemination into discussion. Test frequency, test quality and demands, way of sampling and test consistency can influence product safety. New scientific knowledge can influence the value of the regulation. Whether a country is free of notifiable disease should influence decisions regarding necessary tests for the production bulls. The biosecurity of the semen production process is influenced by several factors. The effectiveness of the antibiotics used is questionable. The extenders for cryopreservation added to the semen can affect product safety. The way materials and storage containers have to be disinfected must be clear. In modern industry, tracking and tracing is an important issue. Worldwide differences in ways of identification of straws do not benefit a proper identification and registration throughout the process. Regulation could help improve the transparency of production and trade. Before anything concerning biohazard is implemented in regulation, each rule should be thoroughly based on scientific research where possible and furthermore it must be possible to enforce the regulation. The effort it takes to enforce the regulation should be in balance with the benefit it provides. An approach to alter regulation quickly is advisable. To produce a safe product that is accepted for international trade is of vital interest for the survival of artificial insemination (AI) in cattle.

Animal Identification Systems↗
PubMed2000

The serological BHV1 status of dams determines the precolostral status of their calves.

Precolostral calves and their dams were serologically investigated for the presence of antibodies against Bovine Herpesvirus 1 in diagnostic tests with a very high sensitivity and specificity. Although the syndesmo-chorial type of placenta of ruminants does not transfer gamma globulins, a large number of calves had antibodies, in most cases in a very low concentration. Significant correlations were found between the serological status of the dam, the status of the calf, and the titre of antibodies. Oral intake of maternal blood by the calf at birth or transmission or leakage of maternal antibodies during pregnancy might be possible causes of precolostrally positive calves. From the results it is concluded that to reduce the risk of obtaining BHV1-positive calves, BHV1-negative dams should be selected for breeding purposes.

Animals↗
PubMed1997

Effect on milk production of vaccination with a bovine herpesvirus 1 gene-deleted vaccine.

A field trial was conducted to determine the effect of vaccination with an inactivated bovine herpesvirus 1 (BHV1) gE-negative marker vaccine on the milk production of dairy cows. The daily milk yield of 455 cows in six herds was measured electronically from six days before vaccination until 14 days after vaccination. The treatment consisted of two injections with either vaccine or placebo, both at an interval of four weeks. There was a small, but significant (P < 0.05), decrease of about 1.4 litres per cow in milk production after a double vaccination, the negative effect being slightly greater after the second vaccination.

Animals↗
PubMed1997

Inactivated bovine herpesvirus 1 marker vaccines are more efficacious in reducing virus excretion after reactivation than a live marker vaccine.

A comparative study was carried out to evaluate the efficacy of three bovine herpesvirus 1 (BHV1) marker vaccines to reduce the reexcretion of virus after reactivation of latent BHV1. A live gE-negative vaccine, an inactivated gE-negative vaccine and an experimental gD-subunit vaccine were tested in three identical experiments in which cattle, latently infected with BHV1, were vaccinated twice before they were treated with high doses of dexamethasone. Virus excretion after dexamethasone treatment was compared with that in BHV1-infected, unvaccinated cattle which served as controls. All cattle, controls and vaccinees, excreted virus. However, the inactivated vaccines reduced virus excretion more efficiently than did the live vaccine.

Animals↗
PubMed1996

An attenuated bovine herpesvirus 1 marker vaccine induces a better protection than two inactivated marker vaccines.

A comparative study on the efficacy of 3 bovine herpesvirus 1 (BHV1) marker vaccines was carried out. An attenuated gE-negative vaccine, an inactivated gE-negative vaccine and an experimental gD-subunit vaccine were tested twice in a vaccination-challenge experiment in cattle. The attenuated vaccine induced the best clinical protection as evidenced by the total absence of clinical signs and fever in cattle. In addition, the attenuated vaccine reduced the shedding of challenge virus significantly more than the inactivated vaccines. Of the inactivated vaccines, the gE-negative vaccine induced a better clinical protection than the gD-subunit vaccine.

Animals↗
PubMed1994

Double blind field evaluation of a trivalent vaccine against respiratory disease in veal calves.

A field trial was performed to determine the effect of a trivalent vaccine on Clinical Respiratory Tract Problems (CRTP) in veal calves. The vaccine has been developed to increase immunity against the causal agents of IBR, BVD and BRSV infection. In total 928 calves, housed in 16 compartments of one herd, were involved. In four compartments of 58 calves each, vaccinated and non-vaccinated calves were housed together. Four other compartments were treated as a whole and 8 compartments were left untreated. CRTP incidence, medications, weight gain, haemoglobulin and IgG level were recorded. From CRTP positive animals, seroconversion and presence of specific bacteriae and/or viruses were measured as well. Results of the compartments where vaccinated and non-vaccinated calves were housed together showed that the incidence of CRTP in vaccinated calves was 0.16 while it amounted to 0.28 in controls. Most cases were found between day 40 and 60 after the start of the trial. Seroconversion for vaccine specific viruses was sporadically found, but the presence of Pasteurella's was confirmed in the majority of cases. Presumably, the higher incidence of CRTP in the control group was due to a higher level of BVDV infection which might facilitate a clinical infection with Pasteurella's. Vaccination was also negatively related to the percentage of affected lungs at slaughter, the number of days antibiotics had to be administered and subsequently to medicine costs, although these effects were not significant. Daily weight gain was significantly affected by CRTP, but not by vaccination. The effects of vaccination in the compartments where calves were either all vaccinated or not-vaccinated, were similar or larger when compared to the effects in compartments where half of the calves were vaccinated.

Animals↗
PubMed1993

[An outbreak of bovine tuberculosis on a dairy farm].

An outbreak of bovine tuberculosis on a dairy farm is described. Following intradermal tuberculination 84 animals out of 111 animals older than 6 weeks had a positive reaction. Of the 34 adult sheep one gave a positive reaction. All animals on the farm were taken over for destruction by the Animal Health Centre. The source of the infection could not be established although there was a strong suspicion that the importation of three older dairy cows had introduced the infection on the farm. A further investigation was done on 45 farms. Two of these farms were infected by buying animals from the dairy farm in question. During the investigations the possible transmission of the infections to people who were in close contact to the infected animals was also investigated. From 35 examined persons 5 had a positive Mantoux-reaction. The outbreak coincided with a political discussion concerning the abolishment of the periodical tuberculination on dairy farms. Since 1 January 1993 the surveillance of bovine tuberculosis in the Netherlands is done by import control and findings in slaughter-houses combined with a good identification system. It is stressed that the examinations of the lymph glands in the slaughter-houses require the necessary attention.

Animals↗
PubMedDate not supplied

An inactivated gE-negative marker vaccine and an experimental gD-subunit vaccine reduce the incidence of bovine herpesvirus 1 infections in the field.

An inactivated glycoprotein E-negative vaccine and an experimental glycoprotein D-subunit vaccine against bovine herpesvirus 1 (V1) were examined for their effectiveness in a randomized, double-bline, placebo-controlled field trial comprising 130 dairy farms. The use of these marker vaccines enabled us to monitor the incidence of infections in vaccinated populations. The aims of this trial were to evaluate whether these vaccines: (1) reduce the proportion of outbreaks in dairy herds; and (2) reduced virus transmission within dairy herds and to what extent. Vaccination with either of the two vaccines significantly reduced the proportion of herds wherein an outbreak occurred as well as the virus transmission within herds, as compared to placebo-treated herds. The estimated number of secondary cases caused by one infectious animal, expressed as the reproduction ratio R, was for both vaccines significantly > 1. This indicates that when BHV1 is introduced into vaccinated herds, major outbreaks may still occur.

Animals↗