sealPurdue Ag and Natural Resource Briefs

April 1998

Pseudorabies outbreaks will affect 4-H swine shows

WEST LAFAYETTE, Ind. -- 4-H'ers and others in search of this year's grand champion hog need to be aware of a swine disease enjoying a resurgence in Indiana and elsewhere.

Cool, damp weather in parts of the United States has created an environment for the pseudorabies virus to thrive. Although the disease has been eradicated in several states, it still can wreak havoc in the upper Midwest and North Carolina. 4-H swine project members and others will need to ask questions and take sanitation precautions when visiting farms this spring.

Hogs are the natural host for pseudorabies, a viral disease they can sometimes carry without their owner's knowledge. Symptoms range from none to sudden death, according to Dr. John Johnston of the Indiana Board of Animal Health Swine Division. Severity of the disease depends on the age and immune status of the animal.

"It's a disease of the respiratory, reproductive and central nervous systems," Johnston said. In pigs under 3 weeks old, loss of appetite, incoordination, depression, vomiting, nervousness, diarrhea and convulsions may occur, followed by death of the entire litter. In older pigs, signs may be fever, loss of appetite, sneezing, coughing, pneumonia, convulsions and occasionally blindness. In sows, owners may see abortion or stillborn pigs.

It can affect other species, he said, including cattle, sheep, cats, dogs and wild animals. Signs in these animals are more severe. The Indiana Board of Animal Health lists incessant scratching to the point of mutilation as the most common symptom, but all typical swine symptoms may be seen. False rabies symptoms -- grinding teeth, excessive salivation, bellowing and excitement -- also may arise.

Pseudorabies cannot be transmitted to humans, and there is no danger to those eating the meat of pseudorabies-positive hogs, according to veterinarians at the Indiana Board of Animal Health.

The disease is spread primarily by nose-to-nose contact, Johnston said, but it also can live for a short time in manure on gates and other surfaces, so it can be picked up on boots and tracked to other pens or farms.

For this reason, said Clint Rusk, 4-H Youth Extension specialist at Purdue University, 4-H'ers and their families shouldn't go from farm to farm looking for a 4-H pig without cleaning boots and clothing between farms.

"There are plastic boots -- almost like baggies -- they can get at veterinary supply stores to wear over their shoes," he said. "They can wear a clean pair at each farm and then dispose of them."

Other recommendations Rusk had for 4-H'ers include:

  • Check with your county Cooperative Extension Service office for specific requirements to show hogs in your county. Also find out if your county will have a "terminal" show, after which all animals must be sold for slaughter, because you may need to purchase an extra animal for state fair exhibition.
  • If you're planning to show swine at the state fair, check health requirements for those swine shows.
  • Before buying a hog, make sure it's been tested for pseudorabies (PRV tested) and has a health certificate.
  • Find out from your state veterinarian if hogs vaccinated for pseudorabies can be exhibited and sold.
  • Isolate new hogs from any other hogs on the farm until they can be tested.
  • Find out if hogs going to shows must be tested and what the valid PRV test period is. In Indiana, for example, every hog going to a show must be tested, and animals cannot be unloaded at the fairgrounds without the appropriate paperwork.
  • Contact your local veterinarian or your state veterinarian for more information on pseudorabies, its control and testing.

CONTACTS: Johnston, (317) 227-0310; e-mail,
Rusk, (765) 494-8427; e-mail,

Fish farmers must learn zebra mussel prevention from A to Z

WEST LAFAYETTE, Ind. -- Looking forward to the 10th anniversary of the American debut of the zebra mussel and looking back at the tens of millions of dollars of damage the miniature mollusk has inflicted on industrial and municipal water users, it's no wonder aquaculture managers are wondering when it's their turn.

Illinois-Indiana Sea Grant aquaculture specialist LaDon Swann says "Anytime now."

The fingernail-sized mussel's ability to thrive in U.S. waters, its remarkable proclivity for proliferation, and its gift for hitchhiking in bilge water or on boat bottoms makes fish farm contamination a foregone conclusion, says Swann, who works out of Purdue University's animal sciences department. In response, Sea Grant has published a series of fact sheets to help aquaculturists prevent or control a zebra mussel infestation.

Commercial aquaculture operations, several of which operate in Illinois and Indiana, may be at risk, he says, because of the large amount of water that accompanies wild-caught fish, brood fish or fry stock that may be introduced to the operation. Undetected Zebra mussel larvae could be suspended in the water, Swann says, or the spat could be introduced though surface water supplies.

"Zebra mussels also can enter an operation through equipment such as nets, baskets and boots that have been used in infested areas," Swann says.

The problems start when the juvenile mollusks begin attaching to virtually any hard surface, including aerators, water supply valves and filtration systems. Because zebra mussels are filter feeders, they prefer settling in high-current areas which will bring a lot of food their way -- such as an intake pump.

Swann says the mussels pose two other potential problems: Some of their European ancestors harbor organisms that can cause diseases in fish, and their American offspring may, too. Also, a fish farm contaminated with zebra mussels could conceivably face quarantine measures or restrictions on where live fish could be shipped.

Because chemical controls can be expensive and could hurt other aquatic life forms including the farm fish, Swann recommends creating a prevention plan to head off zebra mussel infestation along with a monitoring program if an operator suspects that a pond may be affected.

"It's called a Zebra Mussel Critical Control Point Program, where operators identify the points of their operation that may be susceptible to zebra mussel introduction and put measures in place to avoid infestation," Swann says. "The fish farmers would also establish a scouting program for the pest and decide in advance what to do if they find any."

For example, operators may decide to thoroughly filter surface water supplies, steam-clean or ban outside nets, traps and other equipment, and insist on fry and fingerlings from zebra-mussel-free suppliers. They may also use a 1 percent salt solution during fish transport, which has been shown to control juvenile zebra mussels.

Zebra mussel control at the farm, though, is more difficult. Disinfectants such as iodine and calcium hypochlorite aren't completely effective, and stronger ones are toxic to fish. Some aquaculture operations may be able to drain entire ponds to kill off zebra mussels, and for them, Sea Grant researchers recommend a two-week drying out period in either very cold or very hot weather.

Many molluscicides haven't been approved for aquaculture use and may require special permission from state environmental agencies, Swann says.

In any case, zebra mussel control for aquaculturists promises to be more difficult and costly than prevention.

A comprehensive guide to zebra mussel monitoring, Biological Notes 138, by Sea Grant researcher J. Ellen Marsden is available for $3 from the Illinois Natural History Survey at (217) 333-6880. The free publication "What Every Fish Farmer Should Know About the Zebra Mussel" is available from Mississippi Sea Grant at (601) 388-4710.

CONTACT: Swann, (765) 494-6264; e-mail,

Sustainable ag grants available for farmers

WEST LAFAYETTE, Ind. -- Farmers in Indiana and 11 other states can apply until May 1 for Sustainable Agriculture Research and Education (SARE) grants to test the practical side of a sustainable practice or idea.

Individuals can be awarded up to $5,000 for research, and groups of three or more producers working on creative marketing projects can be awarded up to $10,000 from the U.S. Department of Agriculture program. Funding decisions will be made in late June, and funds will be available in mid-fall for the 1999 crop production year.

"The SARE grants allow farmers to do research on the farm," said Jerry Brust, Purdue University Integrated Pest Management specialist. "It is useful because farmers do their own research and learn from one another."

Brian Churchill, a Harrison County farmer who worked with Brust on a SARE project, said: "This program is an excellent tool to try various ideas. This grant helped me to look for ways to produce an earlier crop with a smaller amount of insecticide."

Churchill received a grant to test the practical effects of a new Integrated Pest Management practice on his 35-acre sweet corn operation and to evaluate the use of row covers on cantaloupes.

Churchill installed moth traps in his sweet corn field and sprayed only when insect numbers reached a certain level as opposed to automatically spraying every three to four days. Spraying according to insect population saved approximately $10,000 and 130 trips across the field, he said.

The row covers on the cantaloupes acted as mini-greenhouses to promote early growth, but the labor-intensive procedure only advanced harvest by a week, and it wasn't worth the effort, he said.

Farmers who want to field-test their own methods of sustainable production can get grant applications through the SARE North Central region office at (402) 474-7081 or on the Web at In Indiana, applications are available from the Purdue University Cooperative Extension Service office in each county or by calling (888) 398-4636. The Indiana Commissioner of Agriculture Office also has applications and can be contacted at (317) 232-8770.

The other 11 states in the region are Illinois, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota and Wisconsin.

CONTACT: Brust (812) 886-0198; e-mail,; Churchill (812) 347-3486

Food science recruiters follow coaches' lead

WEST LAFAYETTE, Ind. -- Purdue University's Department of Food Science is signing up "blue chip" freshmen thanks to some recruiting tips from the athletic department.

By identifying "prospects" during their junior year of high school, maintaining regular contact with them until they enroll in college, and then providing administrative counseling and tutoring services once they arrive on campus, the department has grown 137 percent over the last five years.

"In 1992 we had 59 students majoring in food science. This fall the freshman class numbered 37 out of a total of 140 students," says Philip E. Nelson, a professor and head of the department. "Of those 140 students, 33 have some form of a scholarship, and we hope to eventually be able to offer all food science majors some financial support."

Enrollment numbers aren't the only ones going up.

"We've really raised the bar in terms of quality students," Nelson says. "Our freshmen are coming in with better test scores and higher class rankings."

And placement statistics indicate that there is no shortage of jobs for those who complete degrees. "We placed 100 percent of our May 1997 graduates with an average starting salary of $32,000," Nelson says. "Some students had offers as high as $42,000, which is competitive with salaries in some of the more traditional scientific fields."

Now Nelson is fielding inquiries from food science departments around the country hoping to duplicate Purdue's success. He says one of the biggest challenges in recruiting is getting students to consider food science as a major.

"It's no secret that there is a recruiting problem nationally," Nelson says. "Food processing is the largest industry in the United States, but high school students have no idea how broad and varied the field actually is. When asked about what kinds of jobs are available, they immediately think of fast-food restaurants and grocery stores."

The reality is that food science graduates are qualified for careers in product development, research, quality assurance, sales, purchasing and production management.

The department looked at a variety of recruitment models, including those used by business schools and Purdue's own Schools of Engineering. But Nelson, who is chairman of the university's athletic affairs committee, discovered that the model that seemed to have the most relevance was the one used by the Purdue Boilermaker football program.

Using information on high school juniors compiled annually by the Purdue Office of Admissions, the food science department sends career literature to about 9,000 teen-agers who have expressed an interest in both science and attending Purdue. Between 400 and 500 students respond by returning a postcard, and they receive mailings from the department every six weeks.

Nelson estimates that about 10 percent of those students actually end up applying to Purdue.

"This is where our recruiting effort is really stepped up," Nelson says. "The students who apply to Purdue are sent a T-shirt and an 800 number to call for more information. We also encourage a campus visit with a parent and provide them with faculty contacts."

Once the freshman students begin their studies, they are scheduled for mandatory meetings with the department's administrative adviser who sets up tutoring sessions where necessary and can assist with virtually any concern -- personal or academic -- a student may have.

"The students meet with this adviser every two weeks during their first semester on campus," Nelson explains. "We want to do everything possible to get them started on the right foot, because if they're successful, then we're successful."

CONTACT: Nelson, (765) 494-8256; e-mail,

Compiled by Chris Sigurdson, (765) 494-8415; E-mail,
Purdue News Service: (765) 494-2096; e-mail,

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