The use of stockpiled forage for fall and spring grazing is becoming a common strategy to reduce the cost of wintering beef cows. When managed properly, stockpiled forages can meet the nutritional requirements for mature cows in early to mid gestation during the late fall and early winter. Feed value does decline significantly from December through to March and April, however, with adequate supplementation, stockpiled forage can be a valuable resource for early spring calving on pasture.
Manitoba Agriculture, Food and Rural Initiatives forage and grassland specialist Jane Thornton looked at the potential of stockpiled forages in an extended grazing system during a three-year project starting in 2000, when stockpiling was in its infancy. The key then, as it is today, is to graze or hay the stand in mid July, then let it regrow, she says. This will give you the best balance between quality and quantity for grazing from October through to whenever snow conditions make the forage inaccessible.
Mature, dry cows need at least one ton of dry-matter forage per acre to compensate for weather effects in late fall and early winter. Leaving the forage untouched after an early summer graze will provide adequate quantity come fall, but the stand will be mature and of low nutritional quality even more-so if there has been leaf loss. Research through many years consistently shows that quality declines as forage matures, she explains. On the flip side, if the last graze or cut prior to winter grazing is postponed until late summer, the regrowth will be of excellent quality, but the volume won t be there.
Thornton compared the regrowth yield of alfalfa and 11 varieties of grass in field plots at four locations in southwestern Manitoba. Regrowth was highly dependent on growing conditions from year to year. Even under less-than-optimal conditions, the forages known to have strong regrowth potential meadow brome, orchard grass, alfalfa and tall fescue consistently outperformed the others.
Thornton suggests grazing the softer forages, such as meadow brome, earlier in the fall to reduce the risk of losing them under snow cover. Harder grasses, such as fescue and Russian wild rye, are more likely to stay standing, making them easier for the cattle to find in the snow.
The recommendation is to leave about 1,000 pounds per acre (three to four inches of residue) behind after grazing stockpiled forages. Attempting to graze below that level will limit a cow s daily dry-matter intake, resulting in a loss of body condition regardless of the quality of the forage. As with summer grazing, leaving residue behind conserves moisture, protects the soil from erosion and improves nutrient cycling, promoting longevity and productivity of the stand.
The results of the nutritional analyses show that, while all of the stockpiled forages except alfalfa supplied adequate energy (total digestible nutrients) and all but Dahurian wild rye met the crude protein requirements for dry cows in mid-gestation during the fall and early spring, the relative feed value (RFV) of all forages had declined sharply by March, with only tall fescue and timothy being borderline for this class of cattle.
RFV is derived from a formula using the ratio of two fibre components of the forage: neutral detergent fibre (NDF), which represents the total fibre in the forage, and acid detergent fibre (ADF), which represents the smaller and least digestible portion of the forage. The NDF is filling and limits how much the animal is physically capable of consuming.
As a final reminder, Thornton says it s important to plan ahead. Take time this winter to figure out how you will work stockpiled forage rotations into your overall grazing plan for the upcoming year.
For more information, contact Jane Thornton at 204-729-1387.
THE RECORD ON STOCKPILED FORAGES
The following three graphs present an overview of Thornton s findings regarding the suitability of all 12 forages for stockpile grazing three classes of cattle in the late fall and early spring. Again, the quality varied from year to year, therefore, feed testing is the only way to be sure of the quality of your stockpiled forage. The graphs are a handy reference for forage selection if you are faced with having to repair forage stands damaged by excessive moisture or renovate some old stands and are considering stockpiling forages for the first time or expanding your stockpiled acres. However, it is advisable to consult a forage specialist, agronomist or your provincial forage association regarding the suitability of these varieties to your growing area.