Complex sentence: For centuries, ships sailed with livestock in order to provide sailors with fresh food, and ships in the British and early American navies often carried goats, to eat the garbage and other undesirable food, and return milk and butter.
Split into simpler sentences: For centuries, ships sailed with livestock in order to provide sailors with fresh food. Ships in the British and early American navies often carried goats, to eat the garbage and other undesirable food and to return milk and butter.