Winter annuals take a little finesse. They require just the right balance of stocking rates, grazing times and fertility. Done right, they are pounds in the bank. Mismanaged, they can be a disappointing money drain.
Dennis Hancock, Extension forage specialist for the University of Georgia at Athens, said winter annuals can get caught in the lag phase of growth, not producing enough to keep pace with cattle nutrient needs during winter. This can lead to lost body condition, setting the stage for issues such as lower conception rates come spring.
"I've made the mistake of pushing a pasture a little longer or harder than I should have," he added. "We've learned if you ever get behind, it's nearly impossible to get caught back up without destocking considerably."
To stay on track, here are a few guidelines for keeping winter annuals as productive as possible.
1. Stock Wisely. One acre of winter annuals can usually carry 3/4 to 1 animal unit without supplementation. With better grazing management and fertility, that number can be boosted to 1 or 1 1/2 animal units. With additional supplementation, this can be pushed upwards of 2 animal units per acre. An animal unit is not a head but 1,000 pounds of weight.
2. Don't Graze Too Early. Grazing winter annuals when they are 4 inches or less in height significantly reduces total forage yield for the season by as much as one-third. Hancock reports grazing before plants are well-established and 6 to 8 inches high can set plants back to the point they will never fully recover.
"You get down into the lag phase of growth, where recovery is very, very slow, and you can't meet demand," he explained. "Even in a rotational grazing system, you may need to lengthen rest periods by 10 to 20 additional days to help annuals recover that were grazed too early or too aggressively. We generally say when you get to the point where there are 1,500 to 1,800 pounds of dry matter left per acre, you want to rotate [cattle] off of those annuals to a sacrifice paddock where you can feed hay or baleage."
3. Think Wedge. Rotation and timed grazing -- not just height of forages -- is a way of manipulating stocking rates in terms of impact on a paddock. Hancock said this is where the art of grazing comes in. He explained the system based on an example of 10 paddocks in a grazing or feed wedge. The 10 paddocks range from the narrow end of that wedge, where the least amount of dry matter exists (1,800 pounds or less), to the large end of the wedge, where the most dry matter exists (3,000 pounds or more).
"Ideally, you are at the short end of the wedge when you pull [cattle] off and move them to the high end," he said. "Then, by the time you graze that down, the next highest paddock is back to that target, and you move there. I liken it to having bays full of feed, and you use one bay until it gets down to a certain level. If you use them strategically, the feed grows back."
4. Factor in the Weather. Winter annual management has a lot less to do with the weather today than it does with the weather two weeks from today. Thinking and planning ahead will help maintain forage supplies. Hancock said during really cold spells, growth slows significantly, and it may be better to keep cattle in one paddock and graze it down to the point you'd consider it a sacrifice paddock.
5. Waste Nothing. Winter annuals will really jump when the weather warms up and spring approaches. It's a perfect opportunity to set aside paddocks for hay or better baleage. Hancock said making hay in February or March can be challenging, but baleage can be wrapped up at 50% to 60% moisture and will carry the herd over the hard times in great shape. For producers who decide to take this route, he added it's important to get a nitrogen application out to boost yields and make it worth the expense.
6. Fertilize Like You Mean It. Producers are often a little reluctant to put out a fall nitrogen application for winter grazing. But a nitrogen application in the fall will allow the plant to tiller out more for better spring yields.
"Most of the nitrogen fertilizers we have available to us today are urea-based," Hancock said. "They break down in a bacterial-driven process. Those bacteria are more active when it's warm, so in the winter months, it takes longer to make that nitrogen available to the plant. A fall nitrogen application provides dividends in the spring, even if you can't see an immediate impact in the fall."
He recommends 40 to 60 pounds of nitrogen per acre in the fall followed by two more applications from January through mid-April to total 150 pounds.
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