Browsing by Subject "Eber"

Now showing 1 - 3 of 3
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    Effects of immunological castration on the regulation of metabolism in boars
    (2010) Bauer, Aneka; Claus, Rolf
    Compared to surgical castrates, boars have a superior anabolic potential due to gonadal steroids, i.e. androgens and oestrogens. In consequence, they have an improved fattening performance and lean fat ratio in the carcass. However, most male piglets are surgically castrated without anaesthesia within the first week of life to avoid the unpleasant urine-like boar taint which is not acceptable to many consumers. Boar taint is mainly caused by androstenone which is synthesized in the testes together with the gonadal steroids. Skatole is another compound which contributes to the off odour. But this substance has a faecal smell and can be controlled by feeding strategies. Castration without anaesthesia is now regarded to cause acute pain and stress to the piglets, so that surgical castration is no longer tolerated due to animal welfare considerations. Different alternatives are discussed but it appears that active immunization against the gonadotropin releasing hormone (GnRH) is the most practicable alternative to surgical castration. It is based on application of a commercial antigen (Improvac®) two times at an interval of 4 weeks. The second vaccination then leads to a high antibody formation and to a blockade of GnRH and thus luteinizing hormone (LH). In turn, the testicular biosynthesis of anabolic hormones as well as androstenone is inhibited. Several studies found that immunized boars still had a better performance than surgical castrates. One explanation is that immunized boars maintain part of their anabolic potential before the second vaccination and thus the onset of antibody formation. Therefore, an exact time schedule for immunization is required to optimize the fattening period without risk of tainted carcasses at slaughter. Another explanation may be that high growth hormone (GH) concentrations are maintained in immunized boars at a boar specific level. In addition to low GH, barrows also have low concentrations of the anabolic insulin-like growth factor I (IGF-I). The present four studies were performed to investigate the hormonal and metabolic reactions before and after the second vaccination and to clarify why high GH concentrations are maintained. The cause for elevated GH levels in immunized boars could not be identified in the present studies. Nevertheless, results allow an exact timing of the vaccinations and thus an optimal use of the anabolic potential of immunized boars without the risk of tainted carcasses at slaughter. A further improvement of the fattening performance may be realized by feeding strategies and their influence on IGF-I.
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    Immunocastration of male pigs
    (2020) Kress, Kevin Benjamin; Stefanski, Volker
    In Europe, male piglets have been surgically castrated for centuries in order to avoid boar-tainted carcasses and to eliminate boar-specific aggressive and sexual behavior. Surgical castration of male piglets is still legal within the European Union during the first week of life, even without anaesthesia or analgesia. These circumstances have led to increasing societal criticism, as the castration is painful and violates the physical integrity of the animals. In 2010, European stakeholders of the pork chain committed themselves voluntarily to ending surgical castration from 2018 onwards, but at present, more than 2 years later, the majority of male piglets are still castrated surgically without adequate pain relief. Immunocastration is one alternative to surgical castration or pork production with boars. Although this technique is approved for commercial use in Europe since 2009, the market shares of immunocastrates within the European pork market are very low. The main reasons for this low market acceptance are uncertainties whether immunocastration is reliable, competitive and accepted along the pork chain. The main objective of the present doctoral thesis was therefore to investigate the advantages and disadvantages of immunocastration with regard to the three pillars of sustainability aspects. The various sustainability aspects of immunocastration were summarized and reviewed. In addition, the effects of different housing conditions on the reliability of immunocastration were experimentally tested, as was the impact of housing conditions and sex group on the growth performance of male pigs. Finally, the consequences of pork production with immunocastrates and boars on the profitability of German pig production were analyzed with a simulation model using different carcass pricing systems for immunocastrates and risk scenarios for boar taint. Immunocastration is an active immunization against GnRH and consists of two consecutive vaccinations to induce antibodies which temporarily suppress testicular functions and prevent boar taint. It is a method which ensures both a high product quality and a high level of animal welfare. The impact of immunocastration on the three pillars of sustainability has been studied extensively, although a contemporary global overview of its different aspects has been missing. Performance results in immunocastrates are better than in barrows, but worse than in boars. The environmental impact of pork production with immunocastrates is lower than with barrows, but higher than with boars. The level of aggression is considerably lower in immunocastrates compared to boars. Societal concerns are mainly related to food safety, and are not supported by scientific evidence. After the second vaccination, immunocastrates switch physiologically from a boar-like to a barrow-like status. Therefore, the timing of the second vaccination is a fine-tuning tool to balance advantages of boars with their environmental and economic benefits against the increased risk of welfare problems and boar taint. Nevertheless, both the synergic and the conflicting relationships between the pillars of sustainability must be communicated along the value chain to produce tailored pork products. The present doctoral thesis shows that immunocastration can balance the advantages and disadvantages of pork production with boars or barrows, and thus serve as a sustainable alternative for the European pork chain. If used correctly, immunocastration is reliable in preventing boar taint and can be economically competitive with traditional surgical castration. Based on this thesis, future studies might investigate quality assurance systems that reliably detect non-responders, or animals that are incorrectly vaccinated, before slaughter or at slaughter line. In addition, the economic impact of switching from traditional pork production with barrows to pork production with immunocastrates along the entire pork chain should be further analyzed.
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    Steuerungsmechanismen der Spermatogenese beim Eber: Auswirkungen einer GnRH-Immunisierung und anschließender Estradiolinfusion
    (2005) Wagner, Anna; Claus, Rolf
    Whereas the regulation of spermatogenesis is well known in various species, specific differences, however, exist for the boar, which require species-specific investigation. High concentrations of estrogens are synthesized in the boar testis. It is known, that they play a synergistic role for male behaviour and function of accessory sex glands. Additionally, estrogens in the ejaculate reach the female genital tract and contribute to sperm transport and ovulation in the sow. A possible involvement of estrogens in spermatogenesis, however, was not investigated so far. Similarly, high concentrations of glucocorticoids occur in the tubuli of mature boars. Their regulatory function in spermatogenesis so far is unknown. For clarification, boars were actively immunized against GnRH. GnRH stimulates gonadotropin-release from the pituitary. The evaluation of hormone concentrations in blood plasma after GnRH immunization showed unexpectedly, that the gonadotropin FSH is not influenced, whereas LH- and in consequence steroid- (androgen and estrogen) concentrations were abolished. This offers the possiblity to characterize the selecitve function of estrogens in the presence of FSH. Three groups were evaluated: intact boars (n=5), immunized boars (n=5), 17ß-estradiol infused, immunized boars (n=6). All animals were fitted with indwelling cephalic vein catheters on both sides. One of them was reserved for infusion, the other one for uncontaminated blood sampling. All animals were infused with physiological saline over 7 weeks. For the 17ßEstradiol infused, immunized boars, a defined concentration of estradiol was added to the solution. Blood samples were collected over the whole 7-week period for LH, FSH, testosterone and estradiol. Blood samples were later analysed by established radioimmunological procedures. At the end of the 7-week period, all animals were killed. Tissue samples were fixed for histological examination. Morphological criteria included e.g. tubular diameter, seminiferous epithelial height and number of Leydig cells. Imunocytochemical evaluation was performed for mitosis (Ki-67), apoptosis (TUNEL) and the glucocorticoid receptor. The number of germ cell in the tubuli was reduced by 60% in immunized boars compared to the intact controls. These changes were explained by a more pronounced expression of the glucocorticoid receptor in spermatogonia, followed by the appearance of apoptosis in spermatogonia and primary spermatocytes. In consequence these findings demonstrate for the first time an involvment of glucocorticoids in the quantitative regulation of spermatogenesis. They counteract tubular mitosis by reducing the number of germ cells by apoptosis. In the 17ßestradiol infused group of immunized boars, the infusion led to the restoration of physiological estradiol concentrations (230 pg/ml) in peripheral blood plasma. As expected, androgen concentrations were minimal, so that the specific role of estrogens for spermatogenesis could be clarified. Data from the histological evaluation showed, that the expression of the estrogen receptor alpha occured in spermatogonia, selectively in the mitotic active stage of the seminiferous epithelial cycle leading to a 41-50% rise of germ cell numbers compared to immunized boars. The apoptotic rate in the tubuli of the estradiol infused boars however was not changed compared to immunized boars, so that physiological sperm numbers as they are characteristic for intact boars, were not reached. This study shows for the first time that both glucocorticoids and estrogens play an essential role for spermatogenesis in the boar. They are involved in the regulation of sperm yield by influencing the mitosis-apoptosis equilibrium in the tubuli of boars.