Final answer:
The Department of Agriculture derives its authority to regulate pig farms from laws enacted by Congress, such as the Animal Welfare Act which has been amended to support humane treatment of animals.
Step-by-step explanation:
The authority for the Department of Agriculture to impose rules on the management of pig farms and establish minimum standards of shelter for pigs comes from laws passed by Congress. Regulatory agencies like the Department of Agriculture are empowered by legislation enacted by Congress. These laws outline the scope of the agency's authority and its ability to set regulations that support the legislation's objectives. For example, the Animal Welfare Act (AWA), which covers the treatment of certain animals and their living conditions, was a law passed by Congress that has subsequently been amended to provide more specific directions regarding the humane treatment of animals in various settings.