Heat and dry weather hampered both hay and pasture production in Manitoba this year.
Pasturing cattle on alfalfa fields is one option producers have resorted to in a bid to gain adequate feed for their cow-calf herds.
“We don’t have a choice,” said Glenn Friesen, Manitoba Agriculture’s business development specialist for forages. “We need to have feed, and it’s cheaper to graze than it is to go buy feed.”
Friesen offers some advice for producers pasturing cattle on alfalfa, with a particular emphasis on what can be done to ensure the plants have adequate reserves to survive the winter.
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His first recommendation is to rotationally graze alfalfa stands, rather than use continuous grazing.
“By rotationally grazing, you allow an opportunity for it to regrow and replenish its root reserves for the winter season.”
One of the aims is to minimize hoof traffic on the crowns of the alfalfa plants, so cattle should not be allowed to loiter too long in any one paddock.
Where the alfalfa will be rotationally grazed, it may be wise to start the cattle on paddocks that are less vigorous so the plants will have more time to recover before winter.
Soil testing can help determine whether the grazed alfalfa will be able to find adequate nutrients to replenish its reserves for the winter. For producers who decide to soil test before fall, Friesen advised paying attention to potassium and phosphorus in the soil. If the weather co-operates, the alfalfa could still have a few more weeks of growth this year.
Where the alfalfa is being continuously grazed, avoid letting the cattle chew the plants too low. It’s wise to leave at least four inches (10 centimetres) of growth, Friesen said.
As of mid-August, alfalfa fields entered what he referred to as the critical fall rest period. He reminded producers that harvesting alfalfa during this period, either with machinery or cattle, can reduce the plant’s winter hardiness while potentially reducing stand densities next spring.
That changes about a week or so after a killing frost in the fall. The plant material above ground no longer serves a purpose to the roots, so grazing will have less effect on the plants’ winter survival. Leaving something behind to trap snow should be considered, however.
On a related note, Friesen encouraged producers to be aware of the potential for nitrate accumulation in crops harvested for green feed, particularly sorghum, oats and barley. The dry growing conditions in Manitoba this summer increased the potential for problems.
Manitoba Agriculture’s advisers have a simple yes-no test they can do free of charge to tell if nitrates are present or not. If the test indicates nitrates are present, samples can be sent to an accredited lab for more detailed analysis.
