i was going to say what if they jumped over hay, but then i relised that whatever little greedy pig i would have would just preffer to eat his way though the hay than go around or over it.
anyway, i had a idea for a game to play with your cavies, or anything that will buy into this
what if you set up some extra cube or somthing like a maze or racetrack and then you took your cavies and had them "race" eachother. you would get them to go forward by sticking thier favorite treat in front of them and moving it forward at a moderate speed (i'm not trying to have them win the tour de france or anything like that) of course you could give the treat to the winner, and another one to the loser at the end of the "race".
Would this idea work? What are your thoughts or ideas?