Pork producers argue that gestation crates are needed because sows that are housed together in pens will fight, injuring or killing their fellow penmates. The same effect could be achieved with larger pens that kept the animals separate, but allowed them more freedom of movement. There are also other ways of reducing, but not eliminating, aggression besides gestation crates. These include eliminating overcrowding, not mixing pigs from different litters, providing straw or other bedding material, and providing sufficient food that not only meets nutritional needs but satisfies the appetite. Other important means to reduce aggression among sows rely on alternative feeding methods, as many sows will compete with each other for food. These include trickle feeding systems, individual feeding stalls, and electronic sow feeding equipment, all of which resolve feed competition among pigs.