Eating too many acorns can make cattle sick

By Dr. Jim White, MFA Director of Nutrition. 

Acorns drop off oak trees in early fall, and cattle often like to eat them. But acorns, along with oak buds and very young leaves, can be poisonous when eaten in excess. Cattle and sheep are more susceptible than goats, but the toxic compounds in oak, called “gallotannins,” are tough on the kidneys in all ruminants. Immature green acorns are the main culprit as they contain the highest levels of toxins, but cattle could be affected if they eat too many acorns no matter what time of year. 

Cattle with acorn poisoning will have lower dry matter intake and may be weak and listless. The oak gallotannins irritate the gastrointestinal tract, so cattle tend to “hunch up” and have off-color or bloody manure. Often there will be sores in their mouths, and they will become dehydrated. If producers don’t catch these signs early on, the cattle may experience rapid weight loss. 

The best way to prevent losses from acorn poisoning is to preclude cattle access to them. Move the herd away from dropped acorns or consider fencing off larger areas where oak trees are growing. 

Recognizing that this is not possible in many situations, it’s important to provide enough forage and supplements to keep cattle from wanting to eat acorns instead. Most of the time, acorn consumption is tied to a feed availability issue. Problems usually occur in pastures where there is not much grass left or not much hay fed. The amount of acorn toxins 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. Making sure cattle stay hydrated will also help. 

Unfortunately, there is no sure-fire antidote for acorn poisoning. If signs are noticed soon enough, cattle supplemented with protein and good-quality hay should recover. For more progressed symptoms, there are a few care options. According to the Merck Vet Manual, a pelleted ration supplement containing 10% to 15% calcium hydroxide plus access to more palatable feeds may be used as a preventive measure. Calcium hydroxide, anti-bloat medication and purgatives (such as mineral oil, sodium sulfate or magnesium sulfate) may be effective antidotes if administered early in the course of disease. Fluid and electrolyte replacements may also help keep kidneys operating and correct dehydration. 

One of the most practical means of providing calcium hydroxide and other things that will help alleviate the problem is to offer MFA Performance First 20% Shield tub or MFA Performance First 16% tub. It is not effective to use a low-intake “all-in-one” tub, nor is it effective to use a cooked, low-moisture tub. 

MFA does offer a supplement specifically formulated for this situation, Acorn Special Cubes, which are meant to be fed at 2 pounds per head per day to cattle. These cubes also contain calcium hydroxide and modest energy and protein content. However, they are not floor-stocked at MFA locations and would have to be ordered at a 2-ton minimum. That usually makes the Performance First tubs an easier, more economical solution. 

If you are going to provide cattle with calcium hydroxide, feed 0.2 to 0.25 pounds per head per day. Calcium hydroxide is hydrated lime or “builder’s lime.” It is dusty and noxious to handle. If you put calcium hydroxide into a grain mix to top dress, keep the moisture off it. Dry, oily things cattle like to eat work best as carriers, such as extruded soybeans or dry distillers’ grains. Calcium hydroxide that gets wet sets up like mortar, which is why it is used in the brick and block masonry building trades. It is much easier on all concerned to use pressed or poured tubs rather than to add calcium hydroxide directly to feed. 

For acute cases of acorn poisoning, ask your veterinarian about specific treatments. My experience has been that cattle exposed to acorns for a long time do not respond well. Producers need to be aware of the disease and get more nutrition into cattle so that they don’t eat the acorns. Well-fed cattle are more resistant to the toxins, and they are less likely to eat acorns if they have enough forage and feed. Prevention is far more effective than treatment. 

Originally published in the October 2021 Today's Farmer Magazine.