US Department of Agriculture
Usda: National Agricultural Statistics Service
A good site for statistical evidence of the importance of domesticated mammals in feeding this country. Click on any of the animal types and you can retrieve how many were slaughtered.
Oklahoma State University
Oklahoma State University: Breeds of Livestock Cattle
A comprehensive list of most of the breeds of domesticated livestock that are used in the cattle industry. Brief history of their use and links to background and use of each breed.
Oklahoma State University
Oklahoma State University: Breeds of Livestock Goats
A good history of our use of goats and links to the major breeds of domesticated goats and their specific uses.
Oklahoma State University
Oklahoma State Univ: Breeds of Livestock Other Species
This is a good overview of the use of "other species" that one would not immediately think of as a domesticated mammal. Examples include Buffalo and Llamas.
Other
Canadian Federation of Humane Societies: Marine Mammals in Captivity
An article expressing concern about the use of marine mammals in the entertainment industry.