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Kneer, Martin (2009): Histologische Untersuchung der Haut an den dorsalen Karpalgelenken von Mastbullen aus unterschiedlichen Haltungssystemen. Dissertation, LMU München: Faculty of Veterinary Medicine
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Abstract

Histological investigation of the dorsal carpal joint integument of differently housed fattening bulls Aim of this trial was to investigate - both macro- and microscopically - the effects of various surfaces on the integument of dorsal carpal joints, the main stress zones when cattle rest and rise, using differently housed fattening bulls as samples. The histological differences, which result from the varying housing types, were described to assess possible postural deformities and their subsequent consequences for animal protection with the help of the respective re-sults. Additionally the functional circle “rest behaviour” with its respective motion sequence, which is important to the question at hand, was also included in the trial. Fattening bulls are usually held on concrete slatted floor, which serves as surface for moving and resting. Postural integument lesions at the joint regions exposed during the resting and rising process were previously not of scientific interest. They do, however, have a high rele-vance, not only for the assessment of the animals’ well-being, but also regarding possible sub-sequent clinical illnesses and their economic consequences. In this trial animals were divided in four groups (concrete slatted floor with 2,5-3 m2 = con-crete group, 32 animals; rubber topped slatted floor with 2,5 - 3.0 m2/animal = G1-group, 40 animals; rubber topped slatted floor with 4,5 - 5.0 m2/animal = G2-group, 40 animals; straw housing, 6 animals = straw group). The resting, rising and lie down behaviour of the animals was documented (only slatted floor groups) and the integument in the dorsal carpal joint area was macroscopically examined. Samples of the respective integument areas of each carpal joint were histologically examined after slaughtering. In addition samples were laterally taken from the animals housed on straw at the carpal joint integument. These were examined and analyzed as reference specimen for non-pressure-exposed integument (lateral control). The analysis of the resting, rising and lie down behaviour showed that the position change and in particular the stress on the carpal joints is delayed or avoided by animals using atypical motion patterns on concrete slatted floor. The macroscopic inspection of the integument within the area of the dorsal carpal joints con-cerning the trial parameters scab and swelling of connective tissue showed significantly in-creased values in the concrete group in comparison to G1 and G2. The carpal joints of the straw group could not be examined at the relevant time of trial due to high defilement. The histological investigation of the respective pressure-exposed integument areas showed a thickness increase in all experimental groups compared to the results of the lateral control group not exposed to pressure. All integument layers were affected by this increase in thick-ness, its effects increased from the straw over the rubber to the concrete group, while no dif-ferences could be accounted for between the two rubber groups. The so called bursae subcutis occurred in subcutaneous tissue areas with the slatted floor groups, which is to be regarded as adaption to extreme chronic pressure. As reaction to the increased epidermal proliferation rate an accordingly higher developed stratum papillare, which had and increased amount of elastic fibres in the dermis, was found in the concrete group, probably due to the increased shearing forces of the concrete slatted floor. Within the epidermis were the largest morphometric dif-ferences, to which the stratum corneum contributed the most in terms of numbers. Here the results of the concrete group displayed extreme values, which were about 8-times increased in comparison to the straw group. For the three slatted floor types the mitosis rates and the frequency of occurring paraceratosis hyperplasia (nucleated cells in the stratum corneum) correlated as signs of accelerated horni-fication with the layer thickness growth of the epidermis. Deviating values were documented in the straw group. An accumulated presence of inflammation cells could be observed in the concrete and the straw group; it was, however, not statistically significant. While the histological results sug-gested mechanically caused integument lesions as an inflammation cause in the concrete group, various findings pointed to a damage of the integrity of the epidermal barrier function, due to the chemical-physical influence of a wet, liquid manure-impregnated lie down area in the final weeks of life with the straw group. Various histochemical colourings were prepared for the assessment of the keratinisation and hornification of the epidermis. Significant differences between the investigated groups could, however, not be determined. The implemented investigations produced a comprehensive overview of the development of the dorsal carpal joint’s integument under the effects of various housing types and led to a histological explanation of macroscopically visible integument changes. The determined in-tegument changes at the dorsal carpal joint are to be regarded as an attempt of the integument to form a protection against increased mechanical stress. Nevertheless, in case of animals housed on concrete slatted floor, it does lead to the conclusion that a motion pattern which is covering demand and avoids damage is not possible with the rising and lying down process. This demonstrates the high animal-protection risk of this housing type.