It is officially fall, which means the acorns are falling in the Ozarks. Acorns are a staple product of one of the most important and abundant hardwood trees in the Ozarks, the oak tree. According to the Missouri Department of Conservation, Missouri is home to 19 distinct species of oaks and at least 16 hybrid species.

Oaks can be classified into groups as white oaks or black/red oaks. The white oaks produce an acorn that is sweeter to taste and only requires one season to mature, which is equivalent to around three months. Black, or red, oaks produce an acorn that is bitter to taste and requires two seasons to fully mature or is around 15 months. Either type of acorn is ecologically important to deer, squirrel, turkey and other wildlife but can be detrimental to livestock.

As most livestock producers know, animals do not have a specific requirement for food, they have a specific requirement for nutrients, feed is simply the carrier. When determining if a feed ration is appropriate for livestock, producers typically pay attention to several items: availability, affordability, digestibility, nutrient density, location to animal, and toxicity. When cattle aren’t fed adequate nutrients, they may turn more and more to acorns. Consumption of acorns in excess can lead to illness. Acorn poisoning, or oak toxicity, is caused by chemicals called tannins that lead to gastrointestinal problems, kidney damage and death. It generally occurs when acorns fall off trees in the immature green stage, followed by overconsumption by cattle. This usually occurs in pastures where there is not much grass left nor hay available. Oak toxicity can also occur in the spring months when oak buds or immature leaves are overly ingested by livestock. In a study regulated by the U.S. Department of Agriculture, immature acorns can contain up to 15.1 percent tannins, while mature typically contain no more than 4.2 percent tannins.

Oak toxicity can be devastating to a herd. Acute cases may cause death within three days after the onset of toxicity, while chronic cases may linger for weeks to months. Ruminants typically have symptoms that begin as constipation and shift to black, watery stools. Additional disease indicators may include: dehydration, depression, increased thirst, loss of appetite, straining to urinate, weakness, rapid but weak pulse, collapse, or sudden death. While there aren’t many studies that discuss treatment options, a University of Arkansas study indicated that when constipation begins, a one-gallon bottle of mineral oil can be given orally, and activated charcoal can be given to aid in absorption of the tannin toxicity.

With limited treatment recommendations available, prevention should be the focus among producers.

The University of Missouri-Extension informed conservationists that “individual oaks usually take about 30 years before they produce acorns.”

It is important to regularly check the trees in pastures and evaluate the oak population. If the grazing area contains oaks, it is appropriate to fence around them to prevent acorns or immature oak buds from settling into your pastures and being readily available for overconsumption by livestock. If the oaks are unable to be separated from the herd, another option would be supplement feed with hydrated lime.

The most appropriate recommendation is to ensure that livestock have adequate nutrition and do not seek additional food sources. For questions regarding oak toxicity, specific levels of tannins considered toxic, or for additional information regarding acorn poisoning, contact your veterinarian.


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