The only time I've ever used it was for a horse with anemia.
Don't see a reason to use it on my perfectly healthy stock. They already get plenty of vitamins/minerals from their food, hay, and the mineral blocks I put out.
Seriously, how many supplements do people think an animal NEEDS? As long as its diet is nutritionally sound, it should be getting the majority of its necessary vitamins/minerals without supplementing it to death.