Paul McCaughey has no doubt about the merits of alfalfa as a grazing crop.
It can fix nitrogen into the soil, improve fertility and increase the average daily gain of beef cattle on pasture.
One of the challenges is selecting alfalfa varieties best suited for grazing on the Prairies.
Grazing tolerance is an important part of the equation, but researchers have learned that winter survival must also be considered.
A three-year study looking at grazing tolerance in alfalfa found big differences in winter survival depending on the variety, said McCaughey, a pasture management researcher at Agriculture Canada’s Brandon Research Centre.
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Those differences should be considered by producers when choosing alfalfa varieties for grazing, he said.
The study included sites at Brandon, Swift Current, Sask., Lethbridge, Alta., and Mandan, North Dakota.
Ten public cultivars and 13 experimental lines were included.
Researchers studied the persistence of alfalfa in pure stands and in mixtures with meadow bromegrass. They also compared the effects of continuous and rotational stocking on those pastures.
McCaughey said they found relatively few differences among the cultivars when it came to persistence under intensive grazing with continuous stocking.
The continuous stocking, which began in June and continued into September, kept the alfalfa plants grazed to a height of five centimetres.
But during the winter of 1998, researchers found extreme differences in winter survival among the cultivars.
The discovery was made after the second season of continuous and rotational grazing.
McCaughey said cultivars with a greater proportion of the alfalfa subspecies falcata in their parentage were tolerant to grazing and had greater winter survival. Among those varieties were Rambler, Rangelander, Spredor II and AC Yellowhead.
Falcata originated from the Siberian steppes and does well in regions with colder, drier climates.
The research found that cultivars developed for extreme winters survived, while those from other parts of North America, such as Alfagraze and AC Grazeland, did not.
McCaughey suggests that producers on the northern Great Plains first ask about the winter survival of an alfalfa cultivar before asking for its level of grazing tolerance.
