E. (Kika) de la Garza Goat Research Institute at Langston University in Langston, Oklahoma provides a wealth of information and fact sheets for the goat producer.
USDA Forest Service Plant Information Pages - This web site has an amazing quantity of information on invasive species, sometimes on their palatability, and responses to a variety of management tools. It is backed with loads of citations. To use this site, select forb, graminoid (grass), shrub, etc. to go to a page where the plant is represented by it's latin name - the first three letters of the first word and then first three letters of the second word in the title. Click and read!
Targeted Grazing: A Natural Approach to Vegetation Management
This site is provided by the University of Idaho and shares results of published research and on-the-ground projects related to using livestock to accomplish landscape goals such as weed management, fire risk reduction, and restoration. A full handbook on Targeted Grazing is available for dowload on the site.
"A Guide to Plant Poisoning of Animals in North America" by Anthony P. Knight and Richard G. Walter as a book and CD.
Though some of the text is written with the specialist in mind, it is accessible to lay people as well. I have found both the book and the CD invaluable in identifying toxins in plants, signs of poisoning, and medicines or techniques to combat the poison. You can order it at Amazon.com.
"Toxic Plants of North America" by George E. Burrows and Ronald J. Tyrl.
Again, this was written with the specialist in mind, but you can work your way through it. At over $300 new at Amazon.com it may seem expensive, but that's a lot less than the price of a healthy heifer. There is a paperback edition at a third the price, but it has less than a third of the information contained in the hardcover edition.
BEHAVE.net - The BEHAVE consortium (Behavioral Education for Human, Animal, Vegetation and Ecosystem Management) has spent over two decades studying diet selection in animals. Their web site includes downloadable Fact Sheets, and a booklet describing the results of their research and how you can use your livestock to help you manage weeds, reduce fire danger and improve pastures, range, and wildlife habitat.