Hi, welcome to the group. Nice goats; like the expression on the face of the Nubian. Oyster crackers (the little octagon shaped ones), whole in the shell peanuts (big favorite), raisins (for their sweet tooth) and the most favorite, ultimate treat, Oak Tree leafy branches.
Hi, and welcome! Goats are naturally bush eaters, and a flock of wild goats walks gladly 5-10 kilometers every day to find food. Their natural home is in mountains, so climbing and jumping is natural for them.
If you can, do take them on walks, and feed them as much as you can with non-toxic twigs with leaves. There is a list in another thread, but I do not find it. Poplar, pine, maple, apple twigs, whenever you can get it for them. You will prevent many problems if you give them good roughage, like hay and twigs, and spare the more energy compact treats like crackers for special occasions.
If you like to spend time with them, do try to teach them some nice tricks for treats. They will want the treat every time they do the trick, but you will be amazed at the number of different things they are able to learn. Ask @Damfino and the others in here, who actually do train their goats! A nice trick to begin with is to stand on hind legs to reach a nice twig with leaves, and eat it up there.
I am convinced that you have a nice sleeping place for them, a nice feeder above the ground, and a good fresh water supply. Next they also need salt and minerals, to eat when they feel like it. Only two non-producing goats will eat very little, so I suggest you buy from someone who has many animals, who buys different kinds of salt and minerals.