Originally published July 22, 2019 on Alberta Agri-News
What to consider when using fall-seeded winter annuals to extend the grazing season.
“Environmental conditions are making grazing and obtaining winter feed supplies a challenge this year,” says Karin Lindquist, forage and beef specialist at the Alberta Ag-Info Centre. ”Perennial pastures that have experienced stress last fall and into this spring have shown a decrease in forage yield.”
Winter cereals – including fall rye, winter triticale, and winter wheat – are the most commonly used annual species for fall seeding.
“Fall rye is the hardiest of the winter cereals and the most resistant to diseases that may injure or kill the crop in winter and early spring,” she says. “Because of this, fall rye should often be considered a first choice for use as a fall grazing or early spring grazing crop.”
Seeding the winter annuals by mid-August is the optimum time to establish a strong stand. Seeding after mid-August may decrease winter hardiness and reduces productivity of the crop the following spring.
“If good growth occurs, it is possible to graze this crop this fall,” explains Lindquist. “Ideal seeding rates should be around 80 lb. per acre for drier areas, and 110 lb. per acre in areas with higher rainfall or with irrigation. These higher seeding rates will ensure an adequate plant population to maintain maximized forage production.”
Fertilize if necessary and a soil test will help determine how much needs to be applied. “Higher rates of nitrogen will increase the amount of top growth available for grazing. High nitrogen application tends to decrease the cold-hardiness of plants, whereas the application of phosphorus tends to increase over-wintering capability,” she adds.
Lindquist says that nitrate toxicity can be a risk with winter cereals that have been heavily fertilized with nitrogen.
“Stress – or injury – from frost or hail can increase nitrates in plants to potentially toxic levels. Animals can withstand high levels of nitrates better when grazing than when they are feeding on high-nitrate greenfeed or hay. Rumen microbes are able to adjust to higher levels of nitrates over a matter of four to five days, enabling livestock to graze winter cereals in the fall with lower risk of nitrate poisoning.”
Grazing can begin when the plants are 15 to 20 cm – 6 to 8 inches – tall. “Plant growth tends to slow down as day time temperatures decrease,” she adds. “As long as initial fall frosts are not severe and days remain warm to support plant growth, winter annuals tend to stay green and grow until it snows.”
Forage quality of winter cereals is high in protein and low in fibre. Because of that, Lindquist says that often introductions onto new, or immature, stands may cause animals to scour.
“It may last a couple of weeks as animals adjust, after which the dung will become more firm. However, animals on high quality forage will often remain ‘loose’ throughout the grazing period.”
Lindquist highly recommends using a rotational, managed grazing system to keep plants in a vegetative stage of growth, especially in the spring.
“By keeping rotations short and using an adequate number of stock, the winter cereals will continue to tiller and produce leafy material for pasture. Winter cereals regrow quickly – depending on moisture, fertility and daytime temperatures – into September, October and November. If temperatures decrease gradually in the fall, these cereals can remain green down to -20 C.”
“Winter cereals tend to start growing very early in the spring,” adds Lindquist. “Applying nitrogen fertilizer in the spring to promote growth is recommended. Careful management is needed in grazing fall-seeded winter cereals to get maximum productivity. Plants that go through a cold period like winter go through a process called vernalization, which causes the plants to produce seed the following spring. They are quick to produce seed heads in the spring, often by early or mid-May. If seed heads develop, are pollinated and seed set occurs, plant growth is severely reduced. It is best to make sure plants and tillers are grazed while still in the vegetative stage before the stems elongate. Graze the stand with high stocking rates to optimize forage utilization.”
To connect with the Alberta Ag-Info Centre:
Hours: 8:15 am to 4:30 pm (open Monday to Friday, closed statutory holidays)
Toll free: 310-FARM (3276)