'And there in a wood a Piggy-wig stood/ With a ring at the end of his nose' True of Lear's useful pig in 'The Owl and the Pussycat' but why do pigs have such rings in real life?

Pigs are given nose rings in order to inhibit rooting and minimize pasture damage.

http://www.ufaw.org.uk/journal/Volume.%2010%20abstracts.htm

Well, as Old George, a pigman man said down the Red Lion pub, "You know,Fred , Oi've been a- reckoning this here ringing inhibits a range of functional activities, as well as rootimg, and elicits some behaviours that suggest a degree of reduced welfare , Oi be a-darned if it don't !"

Isn't it good to see the centuries- old Cambridge dialect is still clinging on in the face of such pressures from English !