I have discovered with zucchini, the bigger the better. They really prefer the seeds, but will eat the flesh as well. Let them get about 2 feet long and eight inches across, then try it
Warning: be careful cutting them up when they get this big, the skin is TOUGH!
I made soome stuffed zucchini last week. I gave our chicken the seeds and scooped out stuff. We had some left over and I gave it to them. They gobbled it up!!
Monica