TiHo Bibliothek elib - Tierärztliche Hochschule Hannover

Summary
7 Summary
Ungemach, Linda Christine:
The dioxin body burden of primiparous beef cows pastured on exposed
grassland after fattening with uncontaminated feed
The use of dioxin contaminated grassland for feed production or grazing is
associated with the risk of exceeding the maximum permitted levels in feed or food.
Nevertheless, there are some substantial arguments (e. g. flood prevention) for an
ongoing use of these exposed areas. It is achievable to produce feed and food with
dioxin contents below the maximum levels if the production conditions (roughage
production, feeding and animal husbandry) are adapted to this special situation of
exposure.
The aim of this study was to investigate whether a special form of fattening of
primiparous beef cows (so called „Färsenvornutzung“) would allow the use of
grassland which is exposed to dioxins with regards to maximum permitted levels. The
hypothesis of this concept was: If the dioxin contaminated feedstuffs are substituted
by uncontaminated ones before slaughter the dioxin body burden of the animal
decreases, resulting in “safe“ beef (dioxin content < maximum permitted level). The
dioxin burden in the carcasses should be reduced by fattening with uncontaminated
feed during the last months before the slaughter of the animals. Some reduction in
the body burden may occur due to the dioxin excretion via milk, too. Therefore, a
farm with eminently exposed grassland was chosen (Lower Saxonian Elbe Valley) as
the subject of this field work. This farm provided 51 heifers (3 groups: F I, F II, F III)
which initially received potentially contaminated feed: grass in the summer (grazing
on the outer dike) and contaminated grass silage during winter housing. For using
the partly high contaminated feed an official permit was necessary. For a wellfounded
assessment of the dioxin contamination of the habitat, feed and the animals,
multiple matrices were analyzed by HRGC/HRMS for their dioxin (PCDD/F) as well
as dl-PCB contents (LAVES, Oldenburg). These matrices included, among others,
soil samples (LUFA Nord-West, Hameln) of the pasture (outer dike of the river Elbe)
as well as “contaminated“ feed (grass silage and grass from areas on the outer dike).
To ensure that only uncontaminated feedstuffs were used before the slaughter, these
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