Yes, I've known this for many years. The feed store I buy it at makes their own alfalfa hay and products. Alfalfa is so rich, it can mess up hoofs of horses, giraffes, and animal which eats too much of it.
If I buy pellets, I just throw the on the lawn after they come core aerate. I put it in the compost pile, throw it out on the beds, it's just great stuff which is a great mulch as hay. Especially in vegetable beds.
So, now you're on to it. I buy 50 pound bags for about 16 dollars in Georgetown.
V