Cathie Erichsen Arychuk, P.Ag.
Bison Production Specialist
Some bison producers are considering winter grazing on stockpiled pastures. Proper pasture and forage plant selection, along with some pasture management will ensure that adequate forage quality and quantity is available on pasture through the winter.
Provide Quality Forage for Winter Grazing Bison
Bison have the ability to forage through the winter when given an appropriate pasture. Winter grazing offers several opportunities for producers, including less work, more even manure distribution and nutrient cycling on pasture, and possibly reduced winter feeding costs.
Winter grazing requires an appropriate pasture. Bison need to find adequate forage quantity when they dig beneath the snow. Bison need to eat about 2% of their body weight each day in winter on pasture. They need to find enough forage under the snow to justify the energy spent digging for it. A winter pasture needs to be selected in advance of the winter and forage left to accumulate during the growing season.
Winter grazing also requires adequate forage quality. In the winter, after weaning, bison cows should have access to forage with at least 6 to 7% crude protein (CP) and 48 to 50% total digestible nutrients (TDN). The Western Forage Beef Group at Lacombe has been collecting winter pasture forage quality samples for several years. They have found that dormant forage in winter will have good quality if managed properly. Pastures sampled in late November had CP levels ranging from 5.6% to 13%. TDN levels ranged from 52% to 62%. Differences in forage quality depend greatly on management and forage species. Pastures used for winter grazing should contain good stands of low growing, fine-leaved forages. Creeping red fescue, Kentucky blue grass, orchard grass and meadow bromegrass consistently have higher crude protein levels than other forages in the winter. Tall growing, broader leaved plants like smooth brome, timothy and alfalfa tend to have low quality when stockpiled for winter grazing.
Stockpiled winter pastures must be managed to provide the needed forage quantity and quality. When immature forage plants go dormant in the fall, they will provide higher quality feed over the winter. In a year with average moisture, harvest your winter pasture by either grazing or haying early in July. The regrowth on that pasture, left to accumulate over the rest of the growing season, will provide high quality winter pasture. Good soil fertility levels will also help ensure rapid and nutritious forage regrowth. However, forage quantity is at least as important as quality. In a dry year when regrowth will be slow, you may want to take your last cut earlier in the summer, or not at all. The forage you stockpile will be lower in quality, but the needed quantity will be there.
Bison cows work well for winter grazing. Bison are able and willing to dig beneath the snow for forage. They also willingly use snow for moisture in winter. Nutrient requirements of bison are still timed to match forage growth. Bison calve in late March through April. Their lactation peaks in late May and June. This is when the cows’ nutritional requirements are the greatest, and it is timed to match maximum forage quality on pasture. In late fall and winter, nutrient requirements of bison cows are low, and can be met by managed stockpiled winter forage on pasture.
Pasture management is critical for winter grazing to work. Winter pastures need to be included in the total pasture management plan. Effective winter grazing needs specific pastures selected early in the growing season, seeded to appropriate forage species and managed through the year to provide adequate quantity and quality of forage. You will also need a back up plan - some hay or other feed stored in case ice or snow prevents winter grazing for a while. Winter grazing won’t be an advantage if saving on feed costs reduces your calving or conception rates. You will also have to determine if saving pasture for winter grazing is the most effective use of your land base.