COLUMBIA, Mo. – Newly made spring hay finally being baled in June may be toxic for cattle. Hold off on feeding new hay, says 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, hit by a lack of rain that prevented grass and hay growth, ask advice from regional extension specialists. The tough queries get passed on to MU agronomists in Columbia. A weekly teleconference shows no letup as rains remain spotty.

In his weekly update, MU climatologist Pat Guinan indicated more high heat and local thunderstorms. Rains remained sparse across the state last week.

“Herd owners got a triple whammy,” said Roberts. “Drought starting last November hurt pastures and hayfields. The remaining forage remains short on quantity and low in quality. The third threat is toxicity.”

Much hay being made may be toxic, he said. MU Extension centers are receiving fresh nitrate test kits from MU veterinarians.

The second-coldest April on record stopped spring grass leaf growth. Next, the hottest May on record caused a spurt in growth that’s mostly stems and seed heads. “This year forage has little digestible nutrients,” Roberts said.

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 leaked into the stack. Caution is required in safe handling of ammonia.

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

Hay cut from tall fescue may be most toxic. It may contain 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 toxins in three weeks. Half goes away in six months of storage.

During phone calls other topics are covered. A farmer had asked if fescue pasture seeded this spring would make hay for this winter. Roberts urged caution on using new plantings.

“Let grass grow a strong root system before use,” Roberts said. “Caution protects the cost of seeding.” Dry weather slows root growth the first season.

This week, many regional specialists reported hayfields being cut.

Haymakers this spring are plagued by thundershowers that don’t make much rain but slow hay baling.

In his weather update, Guinan said the seven-day outlook calls for spotty thunderstorms, almost nightly. Temperatures are forecast to remain high across the Midwest.

For crop farmers, subsoils contain little water. “It’s about 15 inches short,” Guinan said. “Water for crops must come from the sky.”

MU regional specialists received added drought information last week.