Baggs

There are more than 100 species of toxic plants in Texas pastures and rangelands. Toxic plant poisonings cause an estimated $50 million in livestock losses in the state every year, not including production loss from sick animals or reduced grazing from infested pastures.

Increased knowledge and identification of toxic plants are the first steps to prevent poisoning.

Plants have different levels of toxicity but, most poisonous plants kill animals only if eaten in large amounts over a short period of time. Some toxic plants are not equally toxic to all species of livestock — for instance, hairy vetch is toxic to cattle and horses, but not to sheep or goats.

High-risk areas for toxic plant populations are livestock handling facilities and bedding and feeding areas. The soil is continually disturbed in these areas, promoting the invasion of toxic plants.

Good grazing management practices can reduce or even prevent livestock losses from poisoning. Stocking rates should be reduced in areas known to have toxic plants, and areas under extreme environmental stress should be avoided completely until enough desirable forage is available. Many toxic plants are among the first to green up in the spring and stay green longer into the fall.

Supplemental feeding during these periods will also be of benefit. Always keep out a source of mineral supplement with a phosphorus content — phosphorus is the most limiting factor in most Texas forages. If a chemical herbicide is used to control toxic plants, the pasture should not be grazed until the treated plants have completely dried.

Again, stocking rates are a major influence on toxic plant consumption by animals. As the density of desirable forage plants decreases and they are suppressed, the density of toxic plants will increase and animals will have a higher probability of consuming a larger amount of these poisonous plants.

Correct diagnosis of a poisonous plant death is often difficult. When a sick or dead animal is found, the first step in diagnosis is to determine whether the cause is plant poisoning or infectious disease.

To do this, it is necessary to carefully observe symptoms of the affected animals and have a good knowledge of the plants native to the area.

Assistance is available from your local veterinarians, Texas AgriLife Extension Service, the Natural Resource Conservation Service and the Texas Veterinary Diagnostic Lab.

For help with toxic plant identification, go to www.texnat.tamu.edu/cmplants/toxic.