'Mineral imbalances show up all sorts of different ways. Long-term effects may be cattle that have less immunity to disease, lower weight gain and lower reproduction. Some visible signs include:
Copper deficiency: Rough coat, poor growth, sickness, reproductive failure.
Selenium deficiency: Weak calf syndrome and poor survival of young calves. Weight loss and diarrhea in growing calves. Retained placenta and mastitis in cows.'
You can download a publication from the University of Tennessee on minerals at:
Mineral Nutrition of Beef Cattle (pdf)