Oklahoma State University
Oklahoma State University: Breeds of Livestock Swine
This site provides a good history of the use of pigs and their origins. It has links to specific examples of pigs and what they are used for.
PBS
Pbs Nature: Pigs
This resource offers a clear and concise description of domesticated pigs. Students who need help narrowing their informational search will benefit from this type of condensed resource.
Other
Barnyard Palace: Pigs
This is a site for the basic information on pigs. It gives you the life cycle, why they are raised, facts about their diets, the different species. Along with all that there are a few more interesting facts.