For the last 4 years or so we have offered our cattle free choice minerals using a cafeteria feeder. The feeder has 18 slots that we fill with vitamins, minerals, micro minerals, and salt. Over the course of the year the livestock choose what minerals they are deficient in and make the needed adjustments. We restock the feeder once a week, typically every week different items need to be filled. This is especially true when the cattle move from one field to another.
Over time the cattle and other livestock use less minerals, as the soil is fertilized the cattle are fixing the nutrients in the soil.
The meat from these cattle is high in many vitamins and minerals that we need as well.
We offer the cattle vitamins and minerals, they choose what our farm is deficient in, they then fertilize and strengthen the soil, and finally they nourish us with their vitamin and mineral dense meats.