Hay prices are still high and supply is still short. Many Michigan livestock producers are desperate to stretch forage supplies until spring green-up of pastures or the first cutting of hay. They may wonder if cover crops that were planted last fall can be grazed or hayed this spring to help stretch forage supplies. The answer, in most cases, is yes. Many plant species used as cover crops have long histories of use as forage crops for hay or grazing.
Cool-season cover crops with strong forage histories include all of the small grains (rye, wheat, oats, barley and triticale), annual clovers (crimson, berseem and arrowleaf), red clover, brassicas (turnip, rape, kale, swede, fodder radish) and peas. Only rye, wheat, barley, triticale and red clover will reliably overwinter in Michigan. Crimson clover may overwinter in southern parts of the state. When planted the previous year, these winter annual cover crops can all be grazed beginning early in spring, and may provide several grazing rotations. If a decision is made in late winter about grazing or haying a small grain cover crop that does not contain any legume, forage value may be increased by frostseeding a fast-growing legume such as crimson or red clover into the cover crop during late February or March.
When harvested as hay, haylage or balage, recommended maturity stage is early milk for the optimum compromise of yield and forage quality in small grains. However, small grains can be harvested at earlier maturities for better quality and less yield during a supply emergency. A small grain hay crop may not be ready earlier than perennial hay crops, but it can add some security to a farm’s forage inventory or provide an extra source of sales income.
Livestock should be observed closely when first put on any lush spring pastures, including small grains, because frothy bloat and grass tetany are possible. Standard bloat precautions such as taking the edge off the appetite of hungry animals before turnout, acclimating animals to new pasture gradually over several days, offering a dry hay supplement or adding a bloat preventative to water sources should be taken. Mineral mixes should include magnesium to help prevent grass tetany. Alternately, magnesium can be added to water tanks.
All of the cover crops mentioned above are also excellent choices for spring or summer planting onto open crop ground such as after wheat grain harvest. In this role, they provide a potential forage source as well as ground cover and other values associated with cover crops. Small grain/clover or small grain/brassica mixtures provide more balanced nutrition and greater yield than cover crop monocultures.
There are a few exceptions to the rule that cover crops can be safely eaten by livestock. Hairy vetch is a common cover crop that is not recommended as livestock forage. In cattle and horses, grazing hairy vetch sometimes causes a painful dermatitis across the entire body or neurological signs. This problem is more likely to occur when mature vetch with seeds is consumed or when vetch comprises most of the pasture, and is less likely to occur with hay or haylage than with pasture containing vetch.
Buckwheat should not be fed to horses as pasture, hay or haylage because it can cause photosensitization. Photosensitization occurs as plant compounds break down and make skin hypersensitive to sunlight, leading to severe and painful sunburn on white patches or exposed skin around muzzle or eyes. Photosensitization can also occur in ruminants fed buckwheat forage, but is rare. Fall-planted buckwheat is not a concern when grazing cover crops in spring because it is extremely frost-sensitive and will not overwinter in Michigan, but it is not the best choice for spring or summer plantings that might be fed to livestock.