Grazing cattle generally benefit from a vitamin and mineral supplementation program. Achieving a balance between animal requirements and vitamin or mineral supply can be a challenge because both components are dynamic. That is to say that forage minerals and vitamin precursor concentrations change throughout the seasons, and animal requirements change with stage of production or growth rate.
Furthermore, day-to-day and animal-to-animal mineral consumption is quite variable. For example, in one study, average consumption of a salt-mineral mix for individual grazing steers ranged from 1.7-10.5 ounces per day. While precise balance is just about impossible to achieve, over time, the supplement formulation combined with average consumption should deliver an adequate supply of vitamins and/or minerals lacking in the forage, deliver a targeted amount of additional additives, and avoid creation of imbalances or toxicities.
A mineral balance exercise involves developing a simple, consistent record-keeping system to track forage mineral composition and your cow herd’s average or “normal” mineral consumption patterns during the same time of year. With this information, you can use a nutrition evaluation program to project deficiencies and/or excesses.
You will need an idea of forage mineral concentration, an estimate of forage intake, a current estimate of average daily mineral supplement consumption and the mineral product’s composition from the label. Most beef cattle nutrition evaluation programs provide an estimate of forage intake and an estimate of daily mineral requirements based on an animal’s weight and stage of production.
Several commercial nutrition companies provide services to conduct these balance exercises and follow up by recommending or manufacturing mineral formulations customized to your operation’s needs.
In recent years, commercial livestock nutrition laboratories have incorporated mineral composition analytical services. For example, the lab at Oklahoma State University (OSU) charges $12 per sample to get macro- and micro-minerals. Depending on your level of concern or interest, you might get started by conducting a winter feeding and summer grazing balance. A more ambitious approach might be to collect “hand-plucked” samples from one or more pastures each month. The idea of the hand-plucking method is to select only plants and parts of plants that you believe represent what your cattle are currently grazing. — David Lalman, OSU Extension beef cattle specialist
