I think I read that they do see in colour.
I bought 2 little plastic cat balls with bells in them for my pigs today. Stephen kept nosing one to make it ring, then popcorning round the cage, up to top deck, back to ball and repeat. So maybe try a jingly ball? Alan isn't interested though so it clearly varies as to whether pigs find them fun.
edit: I found where I'd read they see in colour https://www.guinealynx.info/eyes.html
I bought 2 little plastic cat balls with bells in them for my pigs today. Stephen kept nosing one to make it ring, then popcorning round the cage, up to top deck, back to ball and repeat. So maybe try a jingly ball? Alan isn't interested though so it clearly varies as to whether pigs find them fun.
edit: I found where I'd read they see in colour https://www.guinealynx.info/eyes.html