Tail biting is a major problem in modern pig (Sus scrofa) production and results in a reduction of animal welfare and productive performance. Biting behaviour has been shown to be decreased by the use of enrichment objects. In this study, 108 pigs housed in a room with 12 pens
were observed and a sequence of seven different enrichment materials was tested. Gilts and barrows were housed together and received a new enrichment object each week starting from three different points in the fattening period, ie 20, 40 or 70 kg bodyweight. Toy-contact and biting-penmate
behaviour were observed during one hour at day of introduction and five days later. A continuous sequence of seven enrichment objects reduced biting-penmate behaviour and the number of wounds compared to providing only a single toy (chain). This study also confirmed that not every object was
feasible as an enrichment object for growing pigs. Generally, the highest toy contact was observed together with the highest biting-penmate behaviour. Most toy-contact and biting-penmate behaviour was observed between 20 and 40 kg bodyweight and was decreasing over age. Providing a sequence
of toys for the first time induced toy-contact behaviour while reducing biting-penmate behaviour but decreased after applying the same sequence for the second or third time. The presence of a single chain or a sequence of different toys had no effect on growth and feed conversion. The ideal
sequence should maintain toy-contact behaviour without competition in order to avoid biting-penmate behaviour and reduced animal welfare.