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August 2007

Release Date: August 3, 2007

Welcome Rains also Bring Threat to West Texas Sheep and Goats

While this year’s higher than average rainfall in West Texas has been a boon to both farmers and ranchers, the wet conditions have also led to higher concentrations of stomach worm parasites that can be deadly to area sheep and goats.

According to Dr. Michael Salisbury, associate professor of animal science at Angelo State University, the parasite problem is much more common in East Texas and other wetter areas of the country that produce sheep and goats. Now, West Texas ranchers are facing the same dilemma.

“The worm larva can survive out in the pastures for several months without any rain,” Salisbury said. “Then, when there is a lot of moisture and we get heavy dews in the mornings, the larva will get in the water droplets and work their way up on the grass and plants where they are grazed by the sheep and goats.”

The worms work their way into an animal’s stomach and multiply at a rate of hundreds of thousands a day, Salisbury said. They attach to the wall of the stomach, destroy the mucosal membranes and siphon off the blood of the animal, causing it to become anemic.

“Normally, the animals start doing very poorly and start losing a lot of weight,” Salisbury said. “Eventually they die because they suffocate since they can’t transport enough oxygen.”

But, the parasite problem is particularly tricky in West Texas this year because the infected animals are not showing the usual symptoms.

“They are eating enough and their nutrition is good enough that they are still staying fat and they look fine even though they have a huge parasite burden,” Salisbury said. “This year we’ve got a lot of animals that were in great shape, but then it got hot, they are a little stressed and they are having to travel a little more. Producers are finding fat sheep and goats that have died without warning.”

Another factor that has led to the current parasite problem is that producers have not had to worry about the stomach worms for the last couple of very dry years. ASU’s stock of sheep and goats has already had to be de-wormed twice since January, more times than the last two year’s combined.

To prevent further problems, Salisbury recommends a pro-active approach of better range rotation and grazing management. He also encouraged ranchers to conduct fecal egg count tests on their animals to identify which ones may already be infested.

For animals already suffering from the parasites, there are a limited number of de-worming remedies for both sheep and goats available from veterinarians. However, Salisbury warns against across-the-board treatment that could lead to healthy animals building up resistance to the medications.

While most ranchers remain happy to accept this year’s surprisingly plentiful precipitation, those good feelings have been somewhat tempered by the added danger to their animals and the additional requirements for their care.

“That is the drawback to a good year with rain,” Salisbury said. “It has blindsided us all because everything was doing so great. But, it has dried up and warmed up a bit and many of the animals that looked like they were in great condition have the parasites, we just didn’t know it.”

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