round bale in hay field
HAZARDOUS HAY: Farmers putting up hay need to test it before feeding as growing conditions may have increased toxicity levels in the bales. Individuals purchasing hay for the winter should ask about quality.

Warning: Summer hay crop may be toxic

Farmers may face toxic ergovaline and nitrates in spring, summer hay crop.

Newly made spring hay finally being baled in June may be toxic for cattle. Hold off on feeding cattle new hay, advises Craig Roberts, University of Missouri Extension forage specialist.

The longer the hay can be stored after baling, the less toxic it becomes.

Cow herd owners have been struggling with a lack of rain that has prevented grass and hay growth. “Herd owners got a triple whammy,” Roberts says. “Drought starting last November hurt pastures and hayfields. The remaining forage remains short on quantity and low in quality. The third threat is toxicity.”

Tough calls
Hay cut from tall fescue may be the most toxic due to the possible presence of ergovaline, a toxin found in most fescue grass in Missouri.

There’s more risk. Some producers applied extra nitrogen fertilizer this spring to boost growth. But with little rain, that nitrogen did not convert into sugars and proteins after entering the plant. High nitrate content can be toxic, especially in summer annuals and weedy grasses.

Lack of growth from lack of rain last fall cut winter pastures. Often, those were grazed into the ground. That slowed growth in the cool spring this year. There was a short hay crop last year.

Now, producers want to cut and feed new hay. Roberts urges holding off. Baled fescue loses about one third of its toxins in three weeks. Half goes away in six months of storage.

Roberts also cautions using new fescue seeded pasture plantings. “Let grass grow a strong root system before use,” Roberts says. “Caution protects the cost of seeding.” Dry weather slows root growth the first season.

Test it
Since much of the hay being made may be toxic, MU Extension centers are receiving fresh nitrate test kits from MU veterinarians. “This year forage has little digestible nutrients,” Roberts says.

Farmers will want to get hay tested before feeding.

Treat it
The forage specialist urges producers to ammoniate bad hay. That frees nutrients in the forage.

Ammoniation takes covering hay bales with black plastic. Anhydrous ammonia, a nitrogen fertilizer gas, is placed into the stack. Caution is required to safely handle ammonia.

Ammonia breaks down indigestible plant cell walls. It also lowers toxicity.

It is better to be safe than sorry this summer regarding hay and pasture concerns. Make sure to consult an MU Extension agronomist or livestock specialist.

Dailey is a retired MU extension professor. He writes from his home in Columbia.

TAGS: Livestock
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