LITTLE ROCK — This year's larger-than-normal acorn crop poses a serious threat to Arkansas cattle producers. Most animals are susceptible to acorn poisoning, although cattle and sheep are affected most often.

Most species of North America oak trees are considered toxic. Clinical signs of illness occur several days after consumption of large quantities of green acorns in the fall.

Some cattle can apparently eat acorns with no ill effects, while others develop kidney and digestive problems that can lead to death. Dams consuming acorns during the second trimester of pregnancy have produced malformed calves.

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. There usually is not an increase in body temperature.

Constipation is a common early symptom. The 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 body. Large amounts of fluid may be found in body cavities.

Tannic acid in acorns is poisonous and can cause death by severely damaging the kidneys. Sick 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. 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 0.4 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 is 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.

Tom Troxel is the University of Arkansas Extension animal science section leader.