Extending the grazing season into fall and early winter doesn’t just have to be about stockpiling perennials or growing cereals and ryegrass. Many livestock producers have incorporated brassicas into their arsenal either in a mixture or as a monoculture.
“Brassicas can be both highly productive and provide excellent forage quality,” says Rocky Lemus, extension forage specialist at Mississippi State University. “Rape, kale, turnips, and swede have crude protein levels ranging from 12 to 20 percent in the aboveground biomass and 8 to 14 percent in the root or tubers.”
Most brassicas will remain green and lush after the summer grasses like bermudagrass go dormant. They can help close the gap between the time that summer perennials quit producing but before annual ryegrass is ready to graze.
According to Lemus, brassicas require good soil drainage and a soil pH between 5.8 and 6.5. Several planting options exist. Seed can be drilled into a prepared seedbed at a rate of 2 to 4 pounds per acre or broadcasted and cultipacked. No-till establishment is also an option where a perennial grass is first chemically suppressed using a herbicide like paraquat.
Nitrogen is key to both brassica productivity and crude protein nutritive value. “We recommend 50 to 75 pounds per acre of nitrogen after germination to stimulate growth and ground cover,” Lemus says. “If multiple grazings are expected, another 50 pounds per acre of nitrogen needs to be applied between 60 and 80 days after seeding,” he adds. Phosphorus and potassium fertilization need to be based on soil tests.
The excellent forage quality that brassicas provide — sometimes over 90 percent digestibility — is cause for a well-thought-out grazing plan. Lemus recommends strip grazing, allowing animals access to small areas at any one time. In addition to reducing waste, animal intake is more easily controlled. “Make sure to ease animals into brassicas slowly and restrict intake by supplying dry hay,” Lemus explains. This is especially important where brassicas are grown in pure stands.
The extension specialist says that the carrying capacity of a good brassica stand should be about 800 to 1,000 pounds of beef per acre. Lemus suggests leaving a 4- to 8-inch stubble height after each grazing to promote regrowth. Animals can graze closer to the ground as they move through the final grazing.
“If brassica grazing isn’t managed properly, animal disorders can potentially develop,” Lemus cautions. These include bloat, atypical pneumonia (caused by a high rumen pH), nitrate poisoning, hemolytic anemia (a blood disorder), iodine deficiency, and polioencephalomalacia (a brain disorder).
“To avoid these potential problems, brassicas should not constitute more than 75 percent of the animal’s diet,” Lemus suggests. “Make sure livestock have access to dry hay or other grass pastures. Most importantly, don’t turn hungry animals that are not yet adapted to the new feed into a brassica pasture.”
Few grazing options offer the potential forage quality of brassicas. If managed properly and used in concert with stockpiled perennials and winter cereals or ryegrass, the grazing season can be extended significantly while maintaining excellent animal performance.