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                    U.S. DEPARTMENT OF AGRICULTURE
 Poisonous Plant Research: Logan, UT
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ARS Home Pacific West Area Logan, Utah Poisonous Plant Research Docs





- Bulletin 415
- Stakeholder Meetings
- IJPPR
- ISOPP Main
- Poisonous Plants By Toxic Syndrome
- Arrowgrass
- Bracken Fern (Western Bracken)
- Bitter Rubberweed
- Broom and Threadleaf Snakeweed
- Chokecherry
- Copperweed
- Deathcamas
- False Hellebore
- Greasewood
- Halogeton
- Hemp Dogbane
- Horsebrush
- Larkspur
- Locoweed
- Lupine
- Milkvetch
- Milkweed
- Nitrate-accumulating plants
- Oak
- Other toxic plants
- Colorado Rubberweed or Pingue
- Poison Hemlock
- Ponderosa Pine
- Rayless Goldenrod
- Selenium-Accumulating Plants
- Sneezeweed
- Spring Parsley
- St. Johnswort
- Tansy Ragwort
- Threadleaf and Riddell's Groundsels
- Water hemlock
- Yew

Oak (Quercus spp.)headline bar Oak leaves are leathery and deeply lobed with wavy margins. Acorns form at the base of the stems. Oak is a woody perennial.Cattle, sheep and occasionally horses can be poisoned by browsing on oak. Shinnery oak (Quercus havardii) and Gambel (Q. gambelii) oak are the species responsible for most losses. Shinnery oak, or shinnery, is common in the Southwest. Gambel oak, also called scrub oak, is found throughout the central part of the western states. Scrub oak may be a shrub 1.0-1.5 meters high or a tree up to 10 meters high. Shinnery oak grows 0.5-1.0 meters high.Poisoning is caused by young oak browse, sprouts in cutover areas, mature foliage on felled trees, acorns, and fallen leaves. Oak is most dangerous in the budding and leafing stages and when acorns are available. As leaves mature, oak decreases in toxicity.Cattle may get as much as 50 percent of their diet from oak browse without showing signs of poisoning. More than 50 percent of oak browse in the diet will cause sickness, and more than 75 percent will cause death. The toxic substances are thought to be oak tannins.Oak leaves are leathery and deeply lobed, with wavy margins. Acorns form at base of stems (lower center). Oak is a woody perennial.**Where and When It GrowsDistribution map of shinnery oak and gambel oak.**Shinnery oak is a low, spreading shrub that grows in sandy areas. It is found primarily in western Oklahoma, western Texas, and eastern New Mexico. Gambel oak is a shrub or small tree. It grows in dense thickets on foothills and mountain slopes, up to an elevation of 9000 feet. Oak usually starts growing in early spring before other range plants.**How It Affects Livestock**Oak toxins are incompletely identified, but are most likely a gallotannin or a combination of gallic acid and tannic acid. Buds, small leaves and flowers are most palatable and most often associated with livestock poisoning. Poisoning can occur later in the fall and winter when acorns are available. There are anecdotal reports of poisoning when cattle drink water that has soaked oak leaves. Poisoning results in severe enterogastritis and nephrosis. Death from oak poisoning may occur in a few days to 2 weeks after the cattle first show signs.**Signs and Lesions of PoisoningGambel oak or scrub oak**Lack of appetiteGaunt, tucked-up appearanceConstipation, frequently followed by profuse diarrheaWeaknessRough dry hair coat; dry muzzleTendency to remain near water, excessive thirstReluctance to follow the herdEmaciationMucus in droppingsFrequent urination; dark-colored urineEdema: swelling under the jaw and brisket and   ascitesSubnormal temperatureCollapseDeath Gastritis: abomasum and small intestine inflamedSwollen kidneysNephrosis: renal tubular necrosis with tubular hyaline castsUremia **How to Reduce Losses**Livestock losses from oak poisoning can be reduced by conservative grazing and proper seasonal use of shinnery and Gambel oak ranges. In shinnery areas of the Southwest, livestock owners should reserve pastures with the least amount of oak for early spring grazing. The use of supplemental feed containing 10% calcium hydroxide will help reduce losses. In Gambel oak areas, animals should be kept off oak ranges until other forage becomes available and the oak leaves mature.At first signs of poisoning, remove the affected animals from the herd and give them adequate feed and water. In some cases, the use of a mild laxative, such as mineral oil, may be beneficial. Oak can be controlled with tebuthiuron at 0.25- 05 kg ai/Ac applied to the soil in winter. Follow all precautions for handling herbicides.


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