Assuming that the question is asked in earnest, as opposed to a challenge, I feed my guys (I have over 40 adult geese...Sebastopols, Giant Dewlaps in buff and grey and Shetlands) veggies according to what I can get from my local produce wholesaler who delivers to my house on a weekly or bi-weekly basis.
I give them most types of lettuce, though romaine is usually the easiest to get. Sometimes spinach, kale, corn on the cob as a treat and sparingly, shaved carrots, sometimes even salad "mixes". I have also served carrot tops and dandelion greens. There were several types of greens, like mustard greens, that they did not like. (I know that corn on the cob is not a green, nor are shaved carrots.) Because the cost here on the Island is prohibitive for the large number of birds, I go by what my supplier can give me at a good price.
I got some last day for sale apples and made some applesauce last year and it was popular for my horses, goats and fowl.
Truthfully, I give my adults boiled eggs with the shells on, but I mash the boiled eggs, peeled for the babies. I'm concerned about them eating the shells. I chop them and then mash them up. The baby ducks love the same menu.
I'm sure there are other things that I just can't remember, my mind forgets a lot lately. I forgot that he said the geese were six weeks old, for example.
One of my friends is a regional 4H staffer and works for Cornell Extension. She's been helpful in putting me in touch with some excellent sources through Cornell and the Cornell Duck Research Lab (I wrongly called it the Long Island Duck Research lab in the other post). They've been pretty helpful with both my ducks and geese. Dennis Fuller at Wapsi Waterfowl suggested that I start my flock on dried kelp, which I purchase through Brice Wonders. I bought some of my dewlap goslings from Dennis.
I still make tons of mistakes, but the geese love to see the silver pot coming outside! They know it's full of good stuff! I have tried Miss Prissy's yogurt a few times, but so far, the babies haven't loved it. Maybe I'm just a bad cook.