LITTLE ROCK, Ark. — Acorns pose a serious threat to Arkansas cattle producers every fall. Although most animals are susceptible to acorn poisoning, cattle and sheep are affected most often, according to Tom Troxel, head of the animal science section of the University of Arkansas Cooperative Extension Service.

Acorns of most species of oak in North America are considered toxic. The poisoning is thought to be caused by tannic acid, which can cause severe kidney damage and death.

Clinical signs of poisoning occur several days after consumption of large quantities of green acorns in the fall.

"Dams consuming acorns during the second trimester of pregnancy have produced malformed calves," Troxel said.

Some cattle can apparently eat acorns with no ill effects, while others develop kidney and digestive problems that can lead to death, said Troxel.

Symptoms of acorn poisoning include lack of appetite, rough hair coat, a dry muzzle covered with dry, crusty blood, abdominal pain, excessive thirst, frequent urination and thin, rapid pulse. Constipation is a common early symptom. Droppings are often tipped with dark blood, a condition followed by diarrhea with blood and mucous. Edema, or fluid in the tissue, occurs in the lower portion of the body. Large amounts of fluid may be found in body cavities.

Cows may drink large amounts of water, which is eliminated by the damaged kidneys in a clear diluted form.

"The best way to prevent acorn poisoning is to keep cattle away from acorns, but if you fence off an area covered with acorns, you may have to leave the fence up for a while," said Troxel. "Acorns retain high levels of tannic acid for several months."

You can partially protect mature cows grazing on acorn-laden pastures by feeding them 4 pounds of the following mixture each day: cottonseed meal, whole cottonseed or ground soybeans (40 percent), cottonseed hulls or corn (44 percent), hydrated lime (10 percent) and liquid molasses or vegetable oil (6 percent). Use liquid molasses with either whole cottonseed or ground soybeans.

For calves, feed 2 pounds of the mixture per head per day in a creep feeder.

"The goal is to get the mature cows to consume about four-tenths of a pound of hydrated lime each day. Other mixes that provide this rate of intake can be used, but because hydrated lime is unpalatable, the mix should generally contain no more than 10 percent lime. It's difficult to thoroughly mix hydrated lime in supplemental feeds, so molasses or vegetable oil is recommended to prevent the lime form settling out of the mixture."

If a mature cow is constipated because of acorns, administer 2 to 3 quarts of mineral oil orally. Continue treatment as needed, Troxel noted.

Lamar James is an Extension communications specialist with the University of Arkansas.