In the fall, a common question is: “When is my alfalfa safe to graze?” There can be several different scenarios from where this question arises. From operations tight on forage and looking at fall alfalfa growth as a way to stretch grazing to corn fields being used for residue or winter stockpiled pasture with alfalfa fields adjacent, alfalfa can be seen as a source of additional forage and protein to cow diets.
Later than normal temperatures have begun turning plants yellow with wilting near the top, but a good portion of green plant may be still available. At this point in the year, regrowth after grazing is not a concern. Plants that have been able to winterize have already stored up carbohydrates in the crown and roots to initiate growth next spring, so grazing now will be much less stressful to plants.
A side benefit is that grazing alfalfa in late fall or winter can reduce alfalfa weevil infestations by removing stems and plant parts that serve as a wintering site or a spring laying site for weevil eggs.
Stand health also should be considered when making a decision about grazing. Moisture before the ground is fully frozen can result in crown damage from hoof action if grazing occurs, especially in newly established fields. Having a sacrifice area to pull animals off of during inclement weather to avoid excessive damage to the stand may be a good practice to consider. Additionally, wet weather could leave areas with high traffic rough for next year’s haying season. In extreme cases, compaction may also be a concern.
Finally, by grazing down a stand, the snow trapping ability of a field will be decreased. This may not seem like a big deal, but the additional moisture and protection from temperature extremes snow cover can provide should not be overlooked lightly.
If we can safely say that our stand health is not a concern, the real question often being asked is “Can I be sure my cows won’t bloat if they graze my alfalfa?” To be quite honest, you never can be 100 percent certain that alfalfa won’t cause bloat. Bloat occurs in ruminant livestock when gas produced during fermentation becomes trapped inside the rumen.
Bloat risk is highest 3-5 days after a freeze and much lower a week after a hard freeze after plants have fully wilted. Even if grazing during this safer time, use good management methods to reduce the risk further. Have cows full before turning out to alfalfa and allow them to graze for an hour or two initially or access to a small portion of the field. Wait until mid-day, after frost or dew is gone, before turning out. Gradually work up the grazing time or area to allow the rumen to adjust to the new, high-quality diet while plants are still green. Other dry, palatable feeds or even bloat retardants can be provided to minimize risk even further.
Alfalfa can be grazed safely. Just be careful and realistic.
-Ben Beckman is a beef systems Extension Educator serving the counties of Antelope, Cedar, Knox, Madison and Pierce. He is based out of the Cedar County Extension office in Hartington. You can reach him by phone: (402) 254-6821 or email: ben.beckman@unl.edu .