You can feed them quite a few different vegetables and fruits. I think it would be easier to look up what few veggies and fruits they can't eat. XD
Haha! Pigs and guinea pigs are somewhat different. <3 (I've been busy with my guinea pigs all morning, I see pig and think guinea pig!)
Pigs are non-ruminant animals. They have a single stomach in contrast to such animals as cattle and goats. To grow rapidly and efficiently, swine need a high energy, concentrated grain diet that is low in fiber (cellulose) and is supplemented with adequate protein.
Farm grains are the most common and best source of energy feeds for swine. Corn is an excellent energy feed, and is ideal for finishing feed because it is high in digestible carbohydrates, low in fiber, and is very tasty to pigs! But corn alone will not keep pigs growing and healthy. Corn must be supplemented with vitamins to keep pigs healthy.
Other good sources of feed are barley, oats, and wheat. But like corn. all these sources should be supplemented with protein supplements. Some people add antibacterial compounds to their feed to slow the growth of harmful bacteria that occurs naturally in most feeds. In low levels, these compounds increase the growth of pigs and lower feeding costs. They benefit younger pigs (under 100 to 125 pounds) more than finishing hogs. If you decide to use an antibacterial compound, make sure that you pay attention to the withdrawal period listed on the label (the withdrawal period is the amount of time that medicated feeds must be removed from a hog's diet before slaughter).
Pigs weighing 40 to 125 pounds are referred to as growing pigs. From 125 pounds to market weight (about 230 pounds) pigs are called finishing pigs. As a pig grows, the total amount of dietary protein it needs each day also increases; pigs should be switched from the grower (nutrient dense/more protein) to the finisher (less dense) diet when they weigh about 125 pounds.
Pigs should be self-fed (given all the feed they will eat) throughout the feeding period. Self-feeding allows a pig to grow as fast as possible. The daily intake of pigs of different.
Water is the most important part of a pig's diet. One-half to two-thirds of a pig's body is made up of water. Pigs should be supplied with as much clean, fresh water as they will drink. Pigs can live longer without feed than without water.
They also love to forage! So, that could make feed last longer.