Now the salad days of summer are a memory and the days out grazing look numbered, your guineas will still demand fresh veg , a nice variety and in memory of OldBoy nothing too New and Fangled 
I know by the end of October, many piggies will be sampling pumpkin, with varying success.
I was given a marrow, looked online to see if it was ok. Yes but some piggies don't like it. I tried mine on some trimmings (minus seeds) they were most pleased, it vanished 
Ours like sweetcorn in leaves or mini corn. Regular corn is eaten but with less vigour.
Fresh spinach/watercress/rocket mix but not rocket on its own.
They like carrots with leaves, less keen on regular and even less on peelings.
Our GP2 liked beetroot but none of the other do unless it's in salad bags.
Swede - don't even look at it!
Broccoli - we stamp all over your broccoli Pah
They don't eat much in the way of fruit (watermelon and strawberries are scoffed but they're out of season)
Banana slice and a segment of orange sometimes
No to grapes ( "She could've cuttedup the grapes" they mutter)
So what are you proffering these fussy little gourmets?