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2009-05-13 / Miscellaneous

Fallen oak trees and cattle poisoning

By Rene' McCracken


Fallen Oak Trees & Cattle Poisoning

Submitted by: Rene’ McCracken CEP-AgNR Cherokee County


The recent spring storms can offer a worse risk to cattle producers than the loss of power, structure damage, and downed fences.  Often a somewhat overlooked hazard occurs when oak trees fall within a grazing pasture and cattle consume the young buds and leaves.  Most cattle like the taste of acorns or leaves and tend to seek them out. However, hungry cattle will usually consume too many green acorns or leaf buds and will get sick. Their gastrointestinal tracts will be upset; they will develop diarrhea, become dehydrated, constipated and emaciated; and if their consumption is high enough, irreversible kidney damage escalates then death can occur.

Acorn or oak poisoning is caused by chemicals called tannins. It generally occurs when acorns fall off trees in the immature green stage or if during storms or clearing land, trees with budding leaves are left where the cattle can consume them. Usually in pastures where there is insufficient grass or hay, cattle will eat more tannins than their kidneys can filter out.  In many cases, cows that advance to the “downer” stage may die.

To correct the protein and energy deficiencies of a stressed, thin cow herd, provide plenty of good-quality hay. 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 deficiency but leave the cattle lacking in energy.

If you suspect your cattle have ingested acorns or leaves contact your veterinarian immediately.  To confirm the level of poisoning the vet will take blood samples or if needed necropsy the dead cattle to provide a clear diagnosis.  Treatment is of little value in severely affected cattle. However, for the other cattle remaining on the “poor” oak tree pasture, provide supplemental feed containing hydrated lime (calcium hydroxide) and protein, which are “antidotes” for the tannins.  Mix and cube the following feed formulation for breeding cattle (4 pounds per head per day) and use it as a meal creep feed for calves (free-choice lime limits consumption like salt):

Cottonseed meal ......................... 1,040 pounds (52 percent)

Dehydrated alfalfa leaf meal....... 600 pounds (30 percent)

Vegetable oil ............................... 160 pounds (8 percent)

Hydrated lime............................. 200 pounds (10 percent)

Obviously, this type of poisoning can be prevented by removing cattle from areas with oak trees when acorns have recently fallen or when spring storms provide fallen trees or simply removing the trees.  If either of those solutions are improbable for your operation then reserve these pastures for grazing in late fall or winter, when the acorns have had a chance to age, turn brown and become somewhat less toxic.  No matter when the cattle are moved onto “poor” oak tree pastures, remember that they could still be affected if they eat too many acorns.

If you would like more information on cattle nutrition or other extension topics, contact Cherokee County Cooperative Extension Agent Rene’ McCracken at 903-683-5416 or lrmccracken@ag.tamu.edu.

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