Influence of raw material on the occurrence of tail-biting in undocked pigs

Abstract

The aim of this study was to reveal the effects of raw material provision on tail-biting outbreaks in long-tailed pigs. Two different substrates, dried corn silage (SG, n=245) and alfalfa hay (AG, n=245) were provided for the pigs twice per day from the second week of life until the end of rearing. The control of long-tailed pigs (CG, n=231) were kept without the provision of additional raw material. Each tail was scored regarding tail lesions/tail losses once per week with a four-point score (0=no damage/original length, 3=severe damage/total loss). Weight was collected at the beginning and at the end of rearing. The effect of week after weaning, the batch and the interaction between treatment group and batch had highly significant influences on tail lesions (p<0.001). The main concentration of behavioural disorder took place in the rearing phase. Tail-biting started on average two to three weeks after weaning, followed by tail losses one to two weeks later. The effect of batch had a highly significant influence on tail losses at the end of rearing (p<0.001). The number of tail losses decreased with the number of batches and ranged from 98.6% in batch one to 8.5% in batch ten. This can be explained by enhanced and more precise animal observation by stable staff and points out the learning process in the course of the study. At the end of rearing, piglets of all batches had lost their tails to the greatest extent in CGs (48.7%), followed by AGs (45.2%) and SGs (41.3%). There was no clear trend in total weight gain regarding the level of tail lesions and tail losses. Corn silage stayed attractive for the piglets during the whole observation period, whereas the acceptance of the alfalfa hay decreased towards the end of rearing. The daytime, the batch and the day after weaning, as well as the interaction between treatment group and day after weaning had highly significant influences on the overall activity behaviour during rearing (p<0.001). To summarise, the rearing of long-tailed pigs requires intensive animal observation and direct intervention in case of tail-biting outbreaks. A provision of raw material on the floor of the piglet nest (suckling period) and in a piglet bowl (rearing period) from the second week of life until the end of rearing cannot prevent tail-biting during rearing, but reduces the occurrence of the behavioural disorder in long-tailed pigs.