[Image: Cattle]A couple of weeks ago I received a call from a beef cattle producer who had a cow with “peeling skin”. My first reaction was to have the producer consult a veterinarian. That is always the most effective course of action when you have a sick animal. Veterinarians went to school for a long time to learn about the causes and treatment of livestock diseases and disorders and they have experience in what is the best treatment. After a proper diagnosis is made, it could be that this disorder may be prevented. Photosensitization, peeling skin after exposure to sunlight, can be caused by ingestion of certain plants. It can also have other causes. Its prevention is just one reason to identify and eliminate toxic plants from your pasture.
We are entering the warm weather pasture season and the Bermuda grass and Bahia grass pastures are beginning their most productive period of growth and quality. Our spring forage growing conditions have been good. This is not always the case. When cattle, sheep or horses are short on forage, they will often feed on plants that aren’t good for them. Certain cattle have a tendency to feed on ornamental or yard plants under any conditions. It is important to know which plants have a potential to harm livestock and to eliminate these plants whenever they are found. There are many excellent and economical pasture herbicides available that may be used as a management tool to decrease competition from weeds and reduce the incidence of plant poisoning.
Many plants that grow in our native pastures have the potential to poison cattle. Most of the time these plants will be in a pasture for years and will never be eaten by an animal. If the cow doesn’t eat it, it can’t hurt the cow. However, certain conditions such as drought, overgrazing or starvation will cause cattle to consume plants not in their normal diet. In a year of high fertilizer prices, there is a tendency to cut-back on this input. With less fertility, there will probably be less forage, more weeds and more potentially toxic plants. If you reduce fertilizer, don’t reduce weed control.
Curiosity will cause certain individual cows to sample toxic plants. Calves are born knowing that they have to eat, but not what to eat. They learn this by observing their mother and their herd mates. A group of young heifers or steers, confined alone, will often experiment with eating plants not in their normal diet.
How sick the cow becomes could depend which plant it eats, how much it eats, which part of the plant is consumed, growing conditions of the plant, age of the animal and many other factors. To be safe, try to learn which plants are potentially toxic and how to recognize them.
Plants that have shown toxicity to cattle include: pokeberry, jimson weed, bracken fern, cocklebur, horsenettle, nightshade and perilla mint. Two common toxic weeds are sicklepod and hemp sesbania (coffee weed). All parts of the sicklepod plant are toxic whether the plant is green or dry. Hemp sesbania (coffee weed) has most of the toxin in its seeds. Cattle tend to eat hemp sesbania most often in late summer, fall and winter when forage grass is scarce. The coffee senna plant is very toxic, but fortunately is less common in our area. It resembles sicklepod, but its seed pods are straight and flattened. Perilla mint is a small plant that tends to grow in pastures, along roadways and around old home sites. It often shows a distinctive purple coloration on the underside of the leaf. Perilla mint is often consumed by “curious” young animals.
Most ornamental plants are toxic to some extent to farm animals. Some common toxic ornamental plants include: lantana, yew, azaleas, caladium, oleander and iris. These are seldom a problem unless they escape cultivation and grow in a pasture. Lantana and oleander are extremely toxic to cattle in small amounts. These plants grow well in our climate and are prone to escape. Just remember, keep the cows out of the yard and the ornamental plants out of[Image: Azaleas] the pasture.
The most common cause of poisoning by ornamental plants is by accident. The homeowner will prune back a yard plant or remove some of its limbs. If the limbs or the foliage is thrown over the fence into the pasture, a curious cow will often try to see what it tastes like. It only takes a mouthful of oleander or lantana leaves to cause real problems to a cow. To be safe, treat all ornamental plants as if they were toxic to livestock.
Just as weeds and unwanted plants in the pasture can reduce forage yields through competition, they can also cause more direct problems through poisoning. Learn to recognize these potential pests and control them by cultural and herbicidal means.