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Toxins continue to be on producer’s focus for 2013 grazing seasons

by Wyoming Livestock Roundup

If drought conditions persist, livestock producers may want to more carefully monitor their range and water sources for toxins this spring and summer. Colorado State University Extension Livestock Agent Megan Jedlicka discussed various toxins that can affect livestock during a recent webinar.

Jedlicka said producers will want to use good management, take precautions and continually monitor grazing pastures and stock ponds to prevent cattle from becoming poisoned. 

Watching water

Of particular concern in stock ponds is sulfate poisoning, which is sometimes referred to as polio. Cattle infected with polio will show clinical signs like blindness, uncoordination and nervousness. 

Poisoning occurs when sulfate becomes more concentrated in stock ponds and sinkholes by evaporation at levels of more than 2,500 parts per million (ppm). 

“The water may have been safe under normal conditions, but it can become deadly in a drought when the sulfate becomes more concentrated,” she said. 

In addition, if any supplement that is high in sulfate is being fed to the cattle, it can cause more problems. 

“I would urge producers to consult with a nutritionist, monitor their feeding program and  monitor their water quality to make sure they aren’t contributing to the problem,” she noted. 

Stock pond water should be tested frequently to make sure it is safe for livestock to drink. 

“Cattle can develop some tolerance to elevated sulfate waters if they are introduced gradually,” she said.

As temperatures climb this summer, the cattle will also need monitoring for dehydration and salt poisoning. This type of poisoning can occur when the animals are fed high levels of sodium chloride in combination with water deprivation. 

“Sodium concentrations in excess of 5,000 ppm will decrease production in range animals,” she said. “Salt poisoning leads to seizures, as it breaks down gray matter in the brain.”

Grazing monitoring

Jedlicka said if livestock run out of feed and their pastures have been overgrazed, they become desperate and will eat whatever they can. 

“They may eat stuff that they wouldn’t eat in normal conditions, including vegetation with coarse spines or really woody stalks,” she explained. “These poor quality feeds can lead to disease because nutritional requirements are low or alternative feeds are abused.”

“Feeding large amounts of dense, poor quality roughage can cause lesions in the mouth and throat resulting in abscesses of the head region,” she added. “It may put them off feed. They will eat what’s there, whether it’s what’s best for them or not.”

Toxic plants

In addition, Jedlicka said the danger of livestock consuming toxic plants is magnified during a drought. 

“Overgrazing and poor pasture growth forces cattle to seek out less palatable, and potentially toxic, plants,” she said. “Drought stress may actually increase the toxicity of some plants. Locoweeds remain toxic, even during the winter months.”

Depending upon how much they eat and the toxicity level of the plant, animals will exhibit nervousness and may die or abort their fetus. 

“The best management is prevention,” Jedlicka said. “Grazing management to prevent overgrazing, including proper pasture rotation, reduced stocking rates and weed control by fencing, mowing or plowing are important.”

Balancing rations

“Desperation may lead to purchasing feeds of unknown quality and composition,” the livestock agent continued. “In times of desperation, we don’t tend to think everything through as well as we should. Unbalanced rations can lead to dietary deficiencies, and sudden switches in feed can lead to rumen acidosis or diarrhea.”

“There is nothing wrong with feeding something you wouldn’t ordinarily feed, like potatoes or pumpkins,” she said. “Just make sure they are getting a balanced ration.” 

To provide a balanced ration, make sure the roughage is of proper density and acclimate the cattle to new rations slowly.

If cattle undergo an abrupt change from a dry, sparse, poor quality pasture to a lush, rapidly growing forage, they may succumb to Pulmonary Emphysema or “Cow Asthma.”  

Pulmonary Emphysema is caused by high concentrations of the amino acid, L-tryptophan, in forage. 

“The amino acid is converted to a toxin in the rumen, causing an acute reaction in the lungs,” Jedlicka said.

Infected animals may appear breathless, in distress and show open-mouth breathing one to 14 days after an abrupt change in pasture. Death may follow two to four days later. 

Ionophores can prevent or reduce Pulmonary Emphysema if it is fed to the livestock in advance, Jedlicka said.

Mature cows are at the highest risk, so they should be gradually adapted to a pasture over 10 to12 days. 

Producers can also graze the pasture beforehand with less susceptible livestock, like sheep or animals under 15 months.

Gayle Smith is a correspondent for the Wyoming Livestock Roundup. Send comments on this article to

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