Many Oklahoma ranchers have been reaping the benefits of feed cost and overall animal wellbeing by having cover crops available as forage resources heading into winter. However, cover crops are not going to be a viable option for every livestock operator.
“There are a lot of factors that go into using cover crops as a grazing resource in a cost-effective manner,” said Brad Bain, McCurtain County Extension director and agricultural educator. “What works best in one region of the state may not work best in another area. Also, a ranch will have specific operational needs, ranging from soil health and moisture in a pasture to investments in herbicide treatments, planting systems to be used and a host of other considerations.”
The most common crops for winter cover are grasses, brassicas and legumes. Those grasses are typically small grains such as rye, triticale, winter oats and barley, which provide excellent protein and energy throughout the fall and winter. Although forage quality among those grasses will be similar, maturity will differ greatly from one species to the next.
For example, rye produces great fall forage but will mature earlier than the other species in the spring, said Dana Zook, OSU Extension area livestock specialist for northwestern Oklahoma. Developed from a cross of wheat and rye, triticale is a successful forage producer that matures later in the spring, a good choice for graze-out. Winter oats and barley may produce slightly less forage overall, but evidence suggests superior root volume compared with rye and triticale.
In northwestern Oklahoma, OSU demonstration research plots of those grasses indicated fall forage quality will contain 25% to 35% crude protein and 70% total digestible nutrients. In spring, protein will decrease gradually to about 15% crude protein and 60% total digestible nutrients by April.
Turnip, rape, kale and radish are brassicas typically blended with other species. With adequate moisture, those crops grow quickly and produce high-quality forage that contains 15% to 20% crude protein and 60% to 70% total digestible nutrients.
“Producers should plan to graze the bulk of those in the fall because of their susceptibility to cold temperatures,” Bain said.
The only cover-crop legume cattle producers in McCurtain County have asked Bain about is clover. Elsewhere in the state, the Austrian winter pea is a common legume for fall and winter cover. While highly nutritive, they are not typically included in a blend at high volume. Many blends can be expensive, but the U.S. Department of Agriculture’s Natural Resources Conservation Service has programs to help offset the cost for qualifying producers.
The risk of bloat for livestock on cover crops is similar to grazing only wheat or other small grains. Some in the industry believe that grazing a blend of different plants will reduce bloat risk, but more research is needed to substantiate the claim, Zook said.
“To control bloat, prevent mineral imbalances and enhance gain, producers should always provide a palatable mineral with an ionophore to cattle grazing small grains or cover crops in the fall and winter,” she said.
Livestock nutritionist Paul Beck of the OSU Department of Animal and Food Sciences recently shared some insights on using cover crops as a grazing resource on the agricultural television program SUNUP, available for viewing online.
“Sugars increase in turnips after a freeze, making them sweeter,” Beck said. “This is the time of year when cattle will eat both the top of the plant and the root system. Before the freeze, cattle would likely only graze turnips if no other forage was available.”
Cow-calf producers need to keep in mind the relationship between forage quality and weight gain. For a calf to gain two pounds daily, forage quality will need to hover around 12% to14% protein and provide 69% total digestible nutrients.