Übersetzte Kurzfassung:
In conventional pig farms in Germany, the keeping of the animals on slatted floors with automated feeding is the predominant system because it is optimized economically and for work management. However, in these housing-systems behavioral disorders increasingly arise. One of the most serious behavioral disorders is tail-biting, which is attributed to the barren conventional housing-conditions and is considered to be multifactorial. Tail docking, due to reduce the behavioural disorder, is routine in conventional farms so far. In the EU Directive of 2008 on the minimum requirements for the protection of pigs it is already appointed, that tail docking should not be done routinely. However, conventionally managed farms in Germany generally have an expert`s report by which the exceptional case is certified and so almost all conventionally produced pigs in Germany are tail-docked.
The aim of this research was to obtain reliable findings on the effects and the risk of not docking the tails in conventional stables on slatted floors. In addition, possible preventive measures relating to the pen design, the stocking density and the effectiveness of practical countermeasures in acute tail biting by accurate and repeatable experiments under controlled conditions should be tested. For a total of six trial runs, eight identical rearing pens with 10 m² respectively were available. The piglets were stabled at the age of four weeks after weaning and the trial runs each lasted six weeks. During the 6-weeks of the experimental period the tails of the animals were scored twice weekly.
In the first two trial runs (trial runs 1 and 2) the influence of tail docking should be determined under conventional standard conditions. For this purpose, four pens were stocked with tail-docked piglets (two-thirds of the tail had been removed) and four pens were stocked with undocked piglets, all under identical conditions.
In the trial runs 3 and 4 the focus was placed on the influence of housing conditions. Due to the results of the first two trial runs, the question was whether the risk of the occurrence of tail biting can be reduced by changing the housing conditions. For this, all the animals were left undocked. In four pens, the stocking density was reduced (20 animals per pen = 0.5 m² per animal) and the offer of enrichment objects and materials was increased.
In the last part of the experimental series (trial runs 5 and 6) the influence of the stocking density in the enriched pens on the incidence of tail biting should be evaluated.
Therefore, only two of the eight pens were left in standard condition with each 28 animals as a control treatment. The other six pens were equipped with enrichment as in the trial runs 3 and 4. In three of the six enriched pens 20 animals were stabled and in the other three pens 27 animals (one animal less than in the standard pen, because of the space required by the straw rack) to determine the effects of stocking density in the enriched pens.
The results of the first two trial runs showed highly significant differences (Chi² test; p <0.001) between the experimental variants "docked" and "undocked" with regard to the injury and partial losses by tail biting. The docked animals had no serious injuries, while undocked animals suffered massive damage caused by tail biting already in the second week of the experiment (at the age of six weeks).
The results of the trial runs 3 and 4 showed that the pen design has a highly significant effect (Chi² test; p <0.001) on the incidence of tail biting. The animals in the enriched pens had significantly lower tail injuries and tail biting occurred much later and was milder than in the conventional pens.
In the trial runs 5 and 6 the differences in the damages of the tails were also highly significant (chi-square test, p <0.001) between the variants. In the conventional pens serious tail biting occurred, as in the previous trial runs, in the second week of the experiment. In the enriched pens with 20 animals tail biting could be also observed, but the registered stronger injuries were, analogous to the trial runs 3 and 4, significantly lower and occurred significantly later on. In the enriched pens with 27 animals the relative frequency of stronger injuries was significantly higher than with 20 animals, but also significantly reduced compared to the conventional pens.
In conventional pens non-docking the tails brought a significant risk to the occurrence of tail biting. Through the use of enrichment materials injuries could be significantly reduced and delayed. Nevertheless, the risk of tail biting in undocked piglets in enriched pens was higher than the risk in docked piglets in conventional pens.