Histologische Untersuchung der Haut an den dorsalen Karpalgelenken von Mastbullen aus unterschiedlichen Haltungssystemen

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.