I also through the winter buy this nut mixture bird feed which I feed at egg laying time to help with the calcium the females use up for egg production. It has shelled sunflower seeds, peanuts, pistachio nut, pumpkin seeds. I just mix some in with the feed each night to help with calcium. I had lost two females after egg laying season and I figured it out it was the loss of calcium during egg laying season. I read up on it and found out that egg laying pulls all the calcium from the bones and this can kill your goose.
So it is good to use a breeder feed during mating and egg laying season. So I also use these nuts. Boy they love it and think they are getting goose candy....
I also give them different treats throughout the year. Apples, tomatoes, red and green grapes, watermelon, peas. There is much more they will eat other can chime in on that. Romaine lettuce, celery.