Pigs like it, especially if enough many pages are given to ensure that every pig in the pen gets an access to the paper, not just the strongest pigs in the pen. However, as yet there is insufficient knowledge as to whether eating ink has any health effects on pigs or consumers.
Some pig farms use short lenghts of feeder chain as enrichment objects. In this research project, the only feeder chain tested was the type that is entirely made of metal. It turned out to have no more benefits than ordinary metal chain, which scored among the lowest materials tested. Feeder chain with plastic parts was excluded from the study, because it is markedly more expensive than any of the other materials tested. For that reason, it is unlikely to reach a sufficient cost-benefit ratio as compared to the materials tested.
Empty jerry cans or other objects are given on some farms. A few Finnish farms have started to use ice hockey pucks suspended on chains.
The objects have to be attached on pen walls or other parts of the pen structures. A loose object easily ends up in a corner, gets soiled in manure and thus becomes unattractive to pigs. This is the reason why for example balls are useful for a short time only. The material also has significance. Pigs often lose their interest in most metal and plastic objects after the first week, once the effect of novelty has worn off.
Commercial enrichment objects for pigs are not used very extensively, because farmers often coinsider them rather expensive. Additionally, there has not been very much impartial research showing that commercially available enrichment objects would actually reduce tail biting or other problems.