Winter canola would be more valuable to growers if they could utilize it as a dual-purpose forage and grain crop, says Mike Stamm, Kansas State University canola breeder. But more information is needed about its forage potential and the effects of grazing on grain yield, Stamm adds.
“Simulated grazing studies of winter canola have been conducted near Manhattan by K-State agronomists over the past few growing seasons,” he reports. “Preliminary results show that canola makes high-quality, nutritious and highly digestible forage. However, ranchers who graze winter canola can expect a reduction in final grain yield.”
In the tests, he observed varietal differences in grain yield after the forage was harvested.
“The yield of varieties with a prostrate growth habit, or those that produce rosettes that hug the ground, was about the same as that of ungrazed checks,” he says.
One such variety, Griffin, was released this year by K-State Research and Extension. The seed of this first dual-purpose forage and grain variety is expected to be available for planting in fall 2013.
The availability and duration of forage is more weather-dependent for canola than for winter cereals. Canola should not be grazed if the threat of too little fall growth for overwintering exists, which could be the case this year where emergence was delayed by dry weather, says Stamm.
The amount of forage produced by winter canola is variable, says Todd White, K-State forage agronomist.
“Above-ground wet biomass has ranged from 2 to 10 tons per acre, and dry weights have averaged about 0.4-2 tons per acre,” says White.
Ranchers report that their animals develop a taste for canola after a few days of grazing it, and noticeably devour the crop before moving to different forages, says Stamm. Others have noticed cattle are not interested in the crop until after a hard freeze.
Some ranchers have seen gains greater than 3 lbs per day. But preliminary research results show that simulated fall grazing reduces grain yield by 50%, while spring grazing reduces grain yield by 70%, Stamm reports. So he doesn’t recommend grazing if the objective is to produce high grain yields.
“Do not graze canola in the spring unless you intend to graze it out,” he advises.
Stamm and White say to keep these points in mind when grazing winter canola:
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Canola forage should not be grazed if the seed was treated with an insecticidal seed treatment. These seed treatments are systemic and can cause irritation when cattle consume the forage.
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A slightly earlier planting date is advisable to allow for maximum forage growth prior to grazing, but adjustments to seeding rates are not necessary.
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Stock the field when the canopy height is approximately 6-8”. Generally, the most forage is available upon reaching the eight-leaf stage and canola grows vigorously at that stage.
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Adjust the stocking rate so mostly new growth is consumed and remove cattle when only half of the original forage remains. Producers may use flash grazing, which means grazing the canola for a brief period, removing the cattle to allow regrowth and then returning them to the canola forage.
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To better-utilize the crop, graze with younger cattle such as stockers rather than older cows. Smaller animals cause less physical damage to the canola plants.
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No more than 75% of the animals’ ration should be canola, with the other 25% consisting of a lower-quality, high-fiber hay.
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Since canola is relatively low in fiber, producers should exercise caution when introducing cattle to the forage and may want to consider a bloat preventer. Cattle should be full, near a source of fiber and closely monitored when initially placed on canola pasture.
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It’s critical to monitor the crop for nitrate content before and during grazing. High nitrate concentrations may be found in the petioles of the leaves. Thus, after cattle remove the leaves and begin feeding on other plant parts, the risk of nitrate poisoning decreases. Research has also shown that nitrate content decreases significantly following a series of hard freezes.
