It probably depends how long and at what level the ascorbic acid is added. This possibility should be investigated in broilers. A. Recent Australian research shows that rams fed diets deficient in zinc have reduced testosterone synthesizing capacity and impaired development of the seminiferous tubules. These changes can reduce libido and fertility of the rams. I do not know of data with pigs, but a recent trial in the Netherlands with rats suggest that replacing glucose with fructose caused a significant reduction in iron absorption from the small intestine.
Anemia is already a potential problem in the young pigs, so caution is recommended.
It probably depends on the mineral. This would be especially helpful to dairy farmers trying to reduce potassium levels in their dry cow diets. Excess potassium has been associated with milk fever and udder edema. It depends on the size of the steers and the quantity and quality of the forage. Yes, breed can have a significant effect.