Impact of feed, light and access to fibres on tail biting in non-tail-docked pigs

Abstract

Abstract Background Tail biting in pigs is a global welfare issue that has resulted in docking tails in many countries. However, tail docking by itself does not reduce the incitements for tail biting. Therefore, this study aimed to reduce tail biting in a high performing non-tail-docking pig herd with increasing incidences of tail biting. Methods The feed to all pigs was supplemented with amino acids, trace elements, vitamins and fibres. All pigs were also offered fibres in terms of hay silage. Thereafter four fattening stables were allotted into experimental groups as follows; I illuminated with standard fluorescent tubes with an invisible flickering of 30-40% for 14 hours per day; II illuminated with non-flickering led light for 14 hours per day; III illuminated with fluorescent tubes for 2 hours per day (this corresponded to the previous standard illumination and III served as a control group); IV similar illumination as III, but with increased access to hay silage. Tail injuries were registered at slaughter during a period of four years prior to the trial, which was compared with the incidence of tail injuries during an adaptation period of six months and during the trial that lasted for a period of one year. Results The incidence of tail injuries during the four years that preceded the adaption period was 9.2%, and the incidence of tail injuries differed significantly between the buildings as well as with season. During the adaption period, the incidence of tail injuries decreased significantly in all buildings and corresponded to 5.4%. The largest decrease was obtained in IV with extra access to hay silage where the incidence decreased from 11.4 to 4.3 %. During the trial, the mean incidence of tail injuries continued to decrease to 3.0%. There were no significant differences between the stables. Conclusions The incidence of tail biting in fast growing non-tail-docked pigs was successfully reduced by supplementation of the feed with amino acids, trace elements, vitamins and fibres. Additional manipulative material in terms of hay silage accelerated that process and non-flickering illumination may have an impact in preventing tail biting. The results obtained argue for the un-necessity of tail docking pigs, provided that the needs of the pigs in terms of feed ingredients, stocking density and access to manipulative materials are fulfilled.