A free-range farming needs more land than an Intensive pig farming. The free-range pigs have access to pasture and the outside word and there are not confined in enclosures. Free range provides a welfare for pigs and natural behavior such as wallowing, rooting etc. Pigs are heavy grazers; a pig farm must have a good rotation system.
Some farmers will put a ring on pig's nose to avoid rooting, some countries do not allow this. You must provide a shelter for pigs to hide during hot days and a place for pigs to play with mud. Even though they live by eating pasture you still need to give them the right pig's diet. Pastured pigs will have less fat than normal pigs.
Intensive pig farming does not require a large land, all pigs are kept indoors. They don't have access to the outside world, this require small land than a free-range farming. The pig's environment is controlled in terms of humidity, temperature, ventilation and space.
Prevention is always better than the cure. The farmer should always monitor the pigs to identify any sort of illness. Pigs that are sick must be separated from other pigs until they recover. Don't allow people near your farm, some diseases can be passed from pigs to the people and vice versa. Don't allow other animals to be close to your farm. There are many swine diseases, on this book we won't cover all of them.
To avoid many of the diseases - a farmer needs to make sure that the pigs are getting enough quality and clean feed. Pigs must get enough clean water. Pigs must be dewormed. The farm must be warm, clean and ventilated. Pigs must not get any stress. Biting insects such as flies, mosquitoes and ticks must not come closer to your pigs. A good hygiene is essential for a pig farm, flies are attracted to decaying organic and moist areas. Don't over crowd on your pigs.