The following links are provided for information regarding plants poisonous to livestock:

 

Livestock-Poisoning Plants of California

Plants Poisonous to Livestock - Cornell

Plants Poisonous to Livestock - University of Minnesota

Plants Poisonous to Livestock in the Western States - USDA

Plants Poisonous to Alpacas

Plants Poisonous to Llamas

ASPCA - Toxic and Non-Toxic Plant List Horses

Poisonous Plant Threats to Cattle and Horses

Horse Nutrition - Poisonous Plants - Ohio State University

Guide to Poisonous Plants - Colorado State University