Johan A Turkstra

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The objective of this study was to determine the optimal dose of a GnRH vaccine for immunocastration of Chinese male pigs, based on immune, endocrine and testicular responses. Forty-two crossbred (Chinese Yanan x Large White) male pigs were randomly assigned to one of the five treatments as follows: (I) 0 microg (control, n=8); (II) 10 microg (n=8); (III)(More)
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(More)
To use peptides as synthetic vaccines, they have to be coupled to a carrier protein to make them more immunogenic. Coupling efficiency between a carrier protein and a peptide, however, is difficult to control with respect to loading density of the peptide. This makes these carrier proteins poorly suitable for practicle use. Attempts have been reported to(More)
Active immunization to immunomodulate regulatory processes suffers from the disadvantage that the antigen is usually 'self' and therefore poorly immunogenic. This has been well illustrated by the long-standing experience with immunocastration vaccines targeting GnRH, a ten amino acid peptide. Not all animals vaccinated with these vaccines are equally(More)
Surgical castration of young female pigs is common practice in Chinese pig farming today. The purpose of the present study is to investigate anti-GnRH immunization as a practical alternative to surgical castration for female pigs. Thirty-six Chinese female crossbred pigs (Chinese Yanan x Yorkshire) were selected from 12 litters, three pigs from each litter,(More)
In this study, the performance of male pigs immunized against GnRH was determined in relation to the onset of their biological response to the immunization. Pigs were immunized at 9 and 17 wk of age and were housed in a pen together with both a surgically castrated and an intact boar littermate. Feed intake was restricted to 2.8 to 3.2 times maintenance(More)
Active immunization against gonadotrophin-releasing hormone (GnRH) is successfully applied to prevent boar taint in pork. In men, GnRH immunization could be an alternative to hormone therapy in patients with prostate cancer. In this study, a new GnRH vaccine formulation (a modified GnRH peptide conjugate formulated with CoVaccine adjuvant) was investigated(More)
Immunization against gonadotrophin releasing hormone (GnRH) was studied as an alternative for the commonly used surgical castration in stallions. Two GnRH vaccines comprising non-mineral oil adjuvants were evaluated for their potential to induce high antibody titers directed against GnRH and subsequent effects on reproductive characteristics. Twelve(More)
Aggressive behaviour and musth are constant problems in captive and sometimes in free-ranging African elephant bulls. Aggressive bulls are difficult and musth bulls almost impossible to manage without severely restricting their movement either by leg-chaining or using tranquillisers. This study investigated the relationship between faecal androgen(More)