- Many cow calf ranchers use the same mineral mix
all year round. However, the opportunity is available to save a few
dollars per head by adjusting the mineral mix to quality of the forage
during the different seasons. The key mineral that most Oklahoma
cow calf operators must provide via a mineral supplement is phosphorus.
It is very important that cattle not be phosphorus deficient, especially
near the breeding season. Excess phosphorus however can be expensive.
Therefore it makes sense to match the phosphorus supplement with the needs
of the cow and fill the gap left by the forage type that she is grazing.
The 1996 National Research Council's Nutrient Requirements of Beef Cattle
includes phosphorus requirements for cows in various stages of production.
Requirements for cows were slightly lowered from previous publications.
The newest recommended requirements for a large, heavy milking beef cow
are graphically illustrated in this chart.
The units on the vertical axis represent percent of dry matter intake that is consumed daily by the cow. Months of the year are represented on the horizontal axis. During most months of the year some phosphorus supplementation is necessary to make up the difference between the requirements that provided by standing forage such as native range grass. A mineral mix containing 12% phosphorus would be appropriate during the dead of winter as the grass is dormant and low in phosphorus. However in the spring and early summer months, as the grass is green and growing, the need for supplemental phosphorus is greatly reduced. At this time, dry cows are getting adequate phosphorus from forage alone. Spring calving, lactating cows, still need some supplemental phosphorus. During the months of May, June, and July, a mineral mix with 6 - 8% phosphorus should be adequate to make up the difference.
Producers that design their own mineral mix with salt and dicalcium
phosphate ("dical") can adjust the ratio of salt to "dical" to take advantage
of the summer growing season. Changing from 1/2 salt: 1/2 dical,
to a mix that is 2/3 salt: 1/3 dical would save a few dollars. This
is especially appropriate for fall-calving cows. They are already
re-bred, and are nearing the end of lactation for this year.