Retrospektive Feldstudie bei Schlachtschweinen zu den Risikofaktoren der Caudophagie
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Beschreibung
Retrospective field study in slaughter pigs on the risk factors of tail biting
Tail biting is a common problem in pig farming. Pigs affected by tail biting suffer from serious pain, injury and har1m. Additionally, the farms have to face substantial economic loss. To prevent tail biting tail docking in piglets has become a routine procedure used by piglet producers in Germany. This procedure is not in accordance with EU legislation. Hence, it is necessary to find effective strategies to resolve the problem of tail biting amongst pigs without the need of tail docking.
Previous studies have shown that tail biting amongst pigs is a complex and multifactorial phenomenon. However, the mechanisms triggering tail biting have not been fully researched yet.
The study at hand is designed to fill these gaps. Based on data collected by official veterinarians at a German abattoir, 20 commercial fattening pig farms in North-Rhine-Westphalia, Germany, were selected to participate in this study. Depending on pathological findings such as the occurrence of necrosis of the tail tip, pelvic abscesses, abscesses at the base of the tail and spinal abscesses of slaughtered pigs, which all were classified as results of tail biting the participating fattening pig farms were assigned to a high risk and a low risk group of farms. The present study compares 10 fattening pig farms where no pathological findings connected to tail biting could be observed at the abattoir during the previous 18 months (so-called low risk farms, LRF) to 10 fattening pig farms with pathological findings observed in 1 – 5 % of the slaughtered pigs within the previous 18 months (so-called high risk farms, HRF). The working hypothesis was to find correlations between gastrointestinal health and tail lesions originating from tail biting with a focus on the previous nutrition. Since tail biting is known to be of multifactorial origin, all participating fattening pig farms were evaluated using a questionnaire regarding factors known to play a crucial role in the development of tail biting. The results of this survey, which focused on feeding management and the composition of the fed pig feed were then correlated to post mortem analyses of the gastrointestinal tract of the slaughtered pigs from participating farms.
The evaluation of the questionnaire showed that there were no major differences in housing when comparing LRF to HRF. However, the use of antibiotic drugs was higher in HRF than in LRF farms, which could partly be related to the higher occurrence of tail biting in those pigs from HRF. In nine LRF and ten HRF, pig feed samples were drawn for further analysis. Differences in particle size or nutrients could not be detected. It could be observed that the crude fiber level in the samples taken from HRF was lower than the level in samples from LRF. Overall, the measured content of crude fiber in the pig feed sampled in LRF as well as HRF was lower than indicated in the declaration of the feed whereas the analyzed crude protein concentration was higher than declared. The analyses of short chain fatty acids in the gastric and caecal content did not differ in slaughtered pigs from LRF or HRF.
For post mortem studies 40 pigs from LRF and HRF were subjected to pathological / anatomical analyses. The studies were performed on 10 healthy pigs from LRF, which showed no tail lesions and 30 pigs from HRF, which were assigned to three different groups based to condition of their tail (10 healthy pigs with no tail lesions, 10 pigs with fresh acute tail wounds and 10 pigs with chronic healed tail wounds). The post mortem analyses in those pigs mainly focused on gastrointestinal health. In the group of pigs from HRF 87% of animals showed pathological alterations in the gastric mucosa. In 30% of those pigs, gastric ulcers could be detected. In comparison, 50% of the healthy pigs from LRF showed alterations in the gastric mucosa. In one of those pigs a gastric ulcer could be noticed. To further support the pathological / anatomical results, haptoglobin levels in blood samples from 18 slaughtered pigs were analyzed. The levels of the inflammation marker haptoglobin were found to be higher in healthy and pigs with acute lesions from HRF when compared to the samples from healthy pigs from LRF. Nevertheless, an analysis of the expression rate of pro-inflammatory genes such as TLR-5, IL-8, IL-10, IL-17 and NKG2D in samples derived from the small intestine of the slaughtered pigs showed no significant differences in animals from LRF to HRF. However, the analysis indicated that TLR-5, NKG2D and IL-8 had the tendency to be upregulated in pigs with acute lesions from HRF when compared to pigs with chronic lesions from HRF. In addition to haptoglobin levels and gene expression rates, a histological inflammation score of the intestinal tissue of small intestine and colon from pigs from LRF and HRF was assessed. The results of this histological analyses showed that the highest rate of inflammation could be detected in the samples derived from pigs with acute and chronic lesions from HRF when compared to the histological findings in healthy pigs with no signs of tail lesion from LRF.
Due to the limited number of commercial fattening pig farms participating in this study and consequently the limited number of pigs used for post mortem analyses, the interpretation of the results must be classified as preliminary. Nevertheless, the results indicate that there are inflammatory processes ongoing in the gastrointestinal tract of pigs with acute and chronic lesions from farms with a history of tail biting. A strong correlation between gastrointestinal health and tail biting might therefore be postulated. To further prove this hypothesis, larger studies with higher number of participating fattening pig farms will be needed. Only when the mechanisms leading to tail biting are fully understood, will it be possible to take effective measures to prevent the underlying causes of tail biting and resign from symptomatic measures such as tail docking.
Autor*in
Swantje Schumacher
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Caudophagie Schweine Schweinemast Tierernährung Verhaltensstörungen animal husbrandry animal nutrition animal welfare behaviour disorders meat hygiene pig fattening pig feeding pigs tail biting