I would like to know if this particular plant/shrub that I have found in my horse hay bales recently, is toxic to my horses. I have been pulling what I find out of the hay but the hay has an acquired smell from this. Would appreciate any help please. Thanks in advance.
Elbert County Colorado
Thanks for the pictures of the plant you have found in your horse's hay. Unfortunately there are no flowers or seed pods to help be positively identify the plant! I am certain it is not water hemlock, poison hemlock or whorled milkweed that would be highly poisonous to horses. The red stems and linear narrow leaves are suggestive of one of the vetches or perhaps wild liquorice. Neither of these plants are toxic unless eaten in large quantities. You mentioned it has imparted a odor to the hay - does it smell like sage. You did not mention of the horses were eating the plant.
Regardless of what plant it is, it is not a good nutritious plant and you are doing the best thing by removing what you see when you feed the hay. You could take the plant in to your extension office and see if someone can positively identify the plant.
Sorry I cannot be more specific.