Limited grazing of wheat pasture can provide Oklahoma and Southern Plains producers with a protein- and energy-rich forage for mature beef cows by late November and early December. That’s providing it rains, says Nathan Anderson, Oklahoma State University (OSU) Cooperative Extension educator for Payne County.
“The protein requirements of a dry cow can be met by allowing her to graze on wheat pasture for one day and returning her to dry pasture grass or hay for the subsequent two days to three days,” he says. “A pattern of one day on wheat and one day off should meet the protein needs of the same cow after calving.”
He warns that dry grass pasture or hay must be available to provide much of the cow’s energy requirements during “off” days. And the wheat pasture “day” should actually be the amount of time it takes for the cow to graze its fill of wheat forage – three to five hours – rather than 24 hours. That should allow cows to consume enough protein to carry them over while grazing dry grass or hay.
“A three-to-five-hour grazing limit helps to avoid the unnecessary loss of valuable forage due to trampling, bedding down and manure deposits,” Anderson says.
Given typical fall weather conditions, enough wheat forage should be accumulated by late November to early December to supply protein for up to one-and-a-half cows per acre throughout winter. But producers will need to examine their pastures because local conditions vary.
Cow-calf producers using continuous grazing programs should watch for grass tetany, cautions Glenn Selk, OSU Cooperative Extension emeritus livestock specialist.
“Grass tetany will normally strike when older cows are grazing small-grain pastures in the early spring; the danger will tend to subside as hot weather arrives,” he says.
A mineral-deficient condition primarily caused by calcium, and to a lesser degree by magnesium, is thought to be the major factor that triggers the disorder. Grass tetany normally affects older cows nursing calves younger than three months of age. Dry cows are seldom affected.
When grass tetany is suspected, cows should get mineral mixes containing 12-15% magnesium at a rate of 3-4 oz/day. Start supplements a couple of months ahead before tetany is usually a danger so proper intake can be established, Selk says.
“Given that grass tetany also can occur when calcium is low, calcium supplementation should be included as well,” he says.
Grass tetany symptoms from deficiencies of both minerals are indistinguishable without blood tests.
“The treatment consists of intravenous injections of calcium and magnesium gluconate, which supplies both minerals. Cows grazing lush small-grain pastures should be fed mineral mixes containing both calcium and magnesium.”