Chad Gulley

It is not uncommon to have oak trees in and around your pastures where livestock graze. Seems like there is a bumper crop of acorns this year on many oak trees, and these acorns are falling now. Acorns are a good source of food for wildlife. However, they can pose issues to livestock in certain situations.

There are 39 species and varieties of oak in Texas. They range from small shrubs to very large trees. Tannins in the acorns are the toxic agent called gallotannins. These tannins may pose issues to a number of animals in the right concentration.

When forages are scarce, cattle will begin searching for alternative food sources. A good stand of forage, hay or both is the best defense against cattle eating plants or plant parts such as acorns that could pose an issue. In other words, if the cattle are full they are less likely to seek out alternative food sources that could pose issues.

Acorn poisoning may be an issue if enough acorns are consumed by the animal species. Hungry cattle are more likely to consume larger quantities of acorns. Poisoning occurs when green, ripe acorns are consumed in the fall of the year. Some cattle may consume acorns and experience little effects, while other cattle suffer severely.

Signs of acorn poisoning include depression, constipation, poor appetite, diarrhea, rough hair coat, abdominal pain and frequent urination. In some cases, kidney failure may result if not caught early enough. Some cattle will have subcutaneous edema between the rear legs above the udder. Some may also have a bloody froth from the nose after they have been handled.

If you suspect cattle are consuming large quantities of acorns, move cattle to pastures where oak trees are not present. It may also be necessary to temporarily fence off these areas so livestock cannot have access to the acorns. If these affected animals do not die, it may take as long as two to three weeks before they start to recover. Producers suspecting such a problem should contact a veterinarian as soon as possible.

If forage is short, provide enough hay to supply the cattle’s needs, supplementing with a good feed ration if possible. Sickness starts eight to 14 days after the cattle have started eating acorns. The amount tolerated by an animal is influenced by the protein content of its diet. If the protein intake is high, the animal can consume more acorns without having poisoning symptoms.

When feeding hay, consider both the quantity and quality fed, and supplement it if needed with the proper amounts of protein and/or energy supplements. Providing hay that is of poor quality – even in large amounts – might provide adequate energy, but the cattle will be deficient in protein. Providing good hay but not enough of it can improve the protein deficiencies, but leave the cattle lacking in energy.

Cattle suspected of acorn poisoning can be moved from the area and fed hay and supplemental feed. Mix and cube the following feed formulation for breeding cattle: 4 pounds per head per day with a feed mixture containing 52 percent cottonseed meal, 30 percent alfalfa, 8 percent vegetable oil or fat and 10 percent hydrated lime.

Information in this article comes from “Toxic Plants in Texas, Integrated Management Strategies to Prevent Livestock Losses,” Extension resource number B-6105, by Drs. Charles Hart, Tam Garland, Catherine Barr, Bruce Carpenter and John Reagor, Texas A&M AgriLife Extension specialists and veterinarians with the Texas A&M College of Veterinary Medicine and Veterinary Diagnostic Laboratory.