It is a legal requirement for British farmers to provide an outlet for pigs to stop them from becoming aggressive. The Department of Agriculture and Rural Development (DARD) is reminding producers that "it is important to provide environmental enrichment for their animals".

A spokesperson for the department insisted it was a serious message.
"Research shows that this leads to reduced levels of harmful social behaviour such as tail biting.
"Pigs should have permanent access to a sufficient quantity of material such as straw, hay, wood, sawdust, mushroom compost, peat, or a mixture of these," said the spokesperson.
But a touch of dribbling and fancy trotter work is not going to keep your average pig satisfied for long.
"Objects such as footballs and chains can satisfy some of the pigs’ behavioural needs, but can quickly lose their novelty value.
"The long-term use of these items is not recommended unless they are used in conjunction with materials such as those listed above," he said.
There are just over 650,000 pigs in Northern Ireland.
The department is advising farmers to read up on the pig welfare guidance provided by DARD.
