Yay on the cucumber front but little nutritional value. Mine got constipation from it! Best thing I've found is cooked, shelled frozen peas - sorted em out a treat and they can't get enough. Also trying sweet potato and butternut squash...
Mine like courgette, shelled peas and broad beans, red pepper, grapes (peeled), squah, carrots. Less keen on potato and I'm not keen on cucumber as it fouls the water too quickly. Try them on a variety of things and see what they like. I'm going to try mine with a sprout tonight!