Drain tomatoes, reserving juice. Set the tomatoes aside. Add water to juice to measure 2 cups; place in a saucepan. Add barley and cumin; bring to a boil. Reduce heat; cover and simmer for 45 minutes or until tender.
Meanwhile, place zucchini in a Dutch oven and cover with water; bring to a boil. Cook for 6 minutes or until slightly tender. Drain; cool slightly. Slice zucchini in half lengthwise. Scoop out pulp, leaving a 1/4-in. shell. Chop pulp and set aside.
In a skillet, cook beef, onion, garlic and allspice in oil until meat is no longer pink; drain. Add barley mixture, parsley, salt, pepper, tomatoes and zucchini pulp; mix well. Spoon into zucchini shells.
Combine bread crumbs, Parmesan cheese and butter; sprinkle over zucchini. Place in two greased 13-in. x 9-in. baking dishes. Cover and bake at 350° for 35-40 minutes or until zucchini is tender.