With a few decent days in the weather forecast, there’s interest in getting back into the fields and either haying or grazing what’s left of the alfalfa or cereal forages. With the snow and weather we’ve had this fall, there’s definitely a few things to be aware of. Today we’ll talk first about alfalfa and then then cereal grains.
Proper fall management of alfalfa is important to ensure that there are enough carbohydrate reserves heading into winter. The healthier the stand, the less chance of winter injury or winterkill occurring. Once the plant has experienced a killing frost and gone dormant, it safe for the plant to be harvested or grazed as carbohydrate reserves are no longer needed for regrowth this fall.
If grazing alfalfa, there is increased concern for bloat immediately following a killing frost. The general recommendation is to wait at least three to five days after a killing frost before considering grazing. Livestock should be moved onto the field in the late morning or early afternoon after they’ve grazed another pasture so they’re not going onto the field with an empty stomach and then tanking up on alfalfa, potentially causing bloat. Another option would be to feed some dry hay before turning onto the alfalfa field to lessen the risk of bloat in animals unaccustomed to alfalfa.
Regardless of whether you are harvesting the alfalfa by grazing it or swathing it, always leave enough stubble to increase snow capture for the winter. Snow cover helps prevent ice sheeting and protects against temperature fluctuations. If plants are exposed to warm temperatures through the winter, that can cause a break in dormancy and the plant will begin using carbohydrate reserves too early, leading to increased risk of winter injury or winterkill.
Now, how about any cereal forages left out there – forages such as oats, barley, or other grain hays? Any time a plant is stressed, whether it be from drought, frost, hail damage, etc., the potential for nitrate accumulation rises, and cereal forages are especially prone to nitrate accumulation. Thus, with the snowstorms we’ve had, I would suspect there’s potential for nitrate accumulation in some of those plants as snowstorms would certainly count as an environmental stressor.
Nitrates are typically highest in the lowest one-third of the plant stems, so cutting or grazing above that portion will reduce the chance of excessive nitrate ingestion. If grazing, be sure to not overgraze but leave plenty of stubble behind and if swathing, consider raising the header slightly to cut higher up the plant.
If planning to graze a pasture of cereal forages, turn cattle in during the afternoon after they’ve had a full feed. I would certainly recommend a nitrate test before grazing cereal forages. Extension offices can offer a ‘quick test’ or a sample can be sent to a lab for analysis within a few days. It’s important to know if nitrates are present and as depending on the nitrate level, poor performance, abortions in bred livestock, and death can occur. If there is nitrate present, the effects could potentially be mitigated by also feeding some grass hay along with the field that is to be grazed.
Fall Consideration of Alfalfa
Nitrate Toxicity of Montana Forages http://animalrange.montana.edu/documents/extension/nittoxmt.pdf