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Influencing factors on tail biting in fattening pigs considering various environmental conditions Tail biting is a widespread problem in pig production; it is leading to reduced animal welfare and to economic losses. As the cause a multitude of environmental and managemental factors is assumed, single reasons have not been found yet.
The aim of this work was to find the reasons identified in the literature for tail biting in a field study. For this reason, at three slaughterhouses 16,488 fattening pigs from 179 farms were examined for tail lesions post mortem. In 51 plants (33 conventionally and 18 ecologically working), farmers were asked in an interview for information about husbandry conditions and their personal opinion on estimated causes for tail biting and intervention. In addition, on 31 holdings (26 conventionally and 5 ecologically working), a visitation of the site was allowed.
Defined factors (air, enrichment material, light intensity, activity and visual impression of the animals) were evaluated by means of categorization (1 to 3, 1 was the ideal starting condition).
3.5 % (542) of the pigs of conventional origin and 11.8 % (113) of ecologically working farms showed tail lesions. The appearance of tail lesions on farms working ecologically increased because of one farm (outlier plant), where a management failure had occurred. The chance of tail lesion occurrence under special husbandry conditions was calculated by means of Odds Ratios (OR). Without the pigs of the outlier plant the OR was below 2 (p˃0.05). Under inclusion of results of the outlier plant, were the OR increased to 10 (p˂0.01).
Farmers´ assessment of the estimated causes focused on overcrowding and climatic reasons. 72.5 % of them initiated countermeasures, 15.7 % of them mentioned removal of the biting pig as a measure. In most of the multiple answers “removed the biting pig” was also mentioned as a measure.
At the visitations the majority of the conventional farms were at category 1 on air, light intensity and activity, on the factor enrichment material it was at category 2. 80 % to 100 % of the ecologically working plants were categorized at 1 on all those factors. The results confirm the (partly contradictory) data from the literature. A precise single factor was not identified. The outlier plant shows the importance of farm management. Despite of the high OR and the significance, results were not meaningful enough to identify a general influencing factor.
Comments of the farmers relate to their own experience with the phenomenon.
The categorization of the farm visitations constituted an option to calculate impressions making them comparable.