The yellow sweet clover invading some native ranges in the West can make suitable livestock feed. But it’s not very palatable and should only be considered only as a backup or temporary pasture for livestock, says Bruce Bosley, Colorado State University regional extension agent.
Biennial sweet clover is a winterhardy, drought-tolerant legume that grows best on fertile, well-drained, calcareous soils, says Bosley. It includes yellow-flowered and white-flowered varieties and strains, with yellow-flowered sweet clover being shorter, more widely branched, finer stemmed and more drought-tolerant.
“Sweet clover is bitter tasting to livestock due to the presence of coumarin,” he points out. “When livestock chew sweet clover, free coumarin is released, producing an undesirable taste that reduces its palatability.”
When grazing sweet clover pasture, don`t make other forage available for grazing. Livestock graze sweet clover forage sparingly when first turned onto pasture because of the bitter taste, but they soon become accustomed to the taste and graze without difficulty.
Bloat may be a problem when grazing immature sweet clover, but the risk is lower than with alfalfa. Because the danger of bloat always is present, Bosley recommends these precautionary measures: 1) Place livestock on pasture with a fill of dry feed, 2) provide dry feed for animals at all times while on pasture not used previously, and 3) provide an adequate supply of water and salt.
Grazing may begin on second-year sweet clover when new growth is 6-8” tall. When the plants are growing fast, the stocking rate should be heavy enough to prevent them from becoming too coarse and unpalatable. Maintain a minimum stubble height of about 6” to promote regrowth.
Nothing will control sweet clover totally once it’s established on native range. Broadleaf herbicides, such as 2,4-D, will kill the present year`s growth, but new stands establish from dormant seed in the soil for up to 20 years. However, concentrated grazing during August, September and October can reduce plant density. Concentrated grazing reduces root reserves, which increases winterkill. Grazing will not eliminate sweet clover, but should help keep the stand at an acceptable level.
If cut at the proper time and adequately cured, sweet clover hay is comparable to alfalfa in feed value. The crop, especially high-coumarin varieties, should be baled drier than other grass and legume hay, preferably at 17-18% moisture or less for small square bales and 13-14% for large bales because of the coumarin. Sweet clover hay stored too wet will mold and may cause sweet clover bleeding disease when fed as the only roughage to livestock.
“Growing a certified seed of a low-coumarin variety, such as Norgold, can avoid problems associated with feeding moldy sweet clover hay,” says Bosley
Consider all wild sweet clover plants to be high-coumarin varieties, he adds.