Veterinarian provides key deworming details

By MONETTE TAYLOR | South Central Texas Edition

A member of the Corpus Christi Farm and Ranch Show crowd talks to Dr. Faries, one of the featured speakers during the recent show. -Staff photo by Taylor

January 23, 2003 -- Although he may have been "preaching to part of the choir," Dr. Buddy Faries, Extension veterinarian from Texas A&M University (TAMU), discussed livestock parasite control with a standing-room-only crowd at the recent Corpus Christi Farm and Ranch Show.

First and foremost on his agenda was a discussion and explanation concerning the brown stomach worm.

"There are a number of worms that affect cattle. Some are in the stomach; some are in the small intestines; some are in the large intestines. Of those worms that are in the gastrointestinal tract, ... most of them are called 'hair worms,' because they're like little hairs," explained Faries.

"There is one that's most important, and that's the brown stomach worm. It is the most harmful worm."

While there are other hair worms that can affect livestock, most are not that important, according to the veterinarian. When purchasing deworming drugs, the first worm mentioned on the label is always the brown stomach worm.

The management of these drugs and the timing used to kill the worms is of utmost importance, said Faries. While many producers use reasoning such as "when I've got them up," or "because it's been a long time," or "because they (livestock) are looking 'wormy,'" Faries believes these are not valid reasons to deworm cattle.

After explaining that the brown stomach worm is really invisible to the naked eye, Faries said under a microscope they are visible. A number of worms can fit within the confines of a regular paperclip, he explained.

The cycle begins with larvae within manure, dumped on the pasture's grass, are ingested by cattle.

"There's male and female worms that occur in the true stomach ... and the adult worms are feeding on the contents of that stomach. They're not feeding on the lining. They're not sucking blood and they're not irritating the lining," explained Faries.

He claims the worms are mainly carbohydrate feeders, so they are eating whatever hay or grain the cattle eat.

"There's no way those worms can out eat the cow," he laughed. "There's no competition for food. That's been a misunderstanding over a long period of time."

Explaining that the life cycle of the brown stomach worm is only about two months, producers need to be alert to weather conditions that are conducive to producing the problem. Soil temperature must be between

55 and 85 degrees before the eggs will hatch, after being deposited on the pasture in the manure.

When explaining the best time to medicate livestock for worms, Faries believes the timing is very seldom the same - it depends on weather conditions and the part of the country you are in.

"If you want to kill them (worms), you've got to get it right, or they're going to die on you before you get to kill them!" he said.

Older cattle seem to develop an immunity to the worms, so the worms seem to die off earlier. Faries said that for 40 years he's been reading and hearing about the danger of stomach worms, but he bases his conclusions on testing done at TAMU and years of experience.

"If you get into the thousands (of worms), there could be a little bit of a problem, and about the only problem I can find is affecting the appetite," he said.

According to Faries, contamination of pastures is the largest obstacle producers face when addressing the worm problem. He believes in rotating cattle on pastures to help keep the worm population down, and he said he does not believe that drug company representatives can tell what kind of worm is present in manure.

"I'll tell you ... you can't do it!" the veterinarian exclaimed.

Another misunderstanding among some producers is that the larvae can crawl up the blades of grass, once the manure hits the ground. Faries said the only way the worms can move is by swimming, and that requires rains or extreme moisture, such as a very heavy dew.

Faries explained there is usually a curve in weather conditions which contribute to deciding when the best time to deworm your livestock, and that usually happens between April through June and/or September through December. Those are the two periods when the soil temperature and the rains are usually more prevalent in South Central Texas.

Deworming during these periods should kill the worms before they have a chance to lay the eggs that are passed through the livestock to the pastures in the manure.

Faries mentioned "bottle jaw" as one visual symptom producers sometimes use to diagnose a wormy animal. Actually, what really causes "bottle jaw" is when the plasma in the blood vessels has moved outside of the blood vessels, and gravitates down to the lowest part ... the jaw. Faries said that happens when the blood protein drops below normal, and really has nothing to do with worms. Many times, malnutrition is the problem, he concluded.